Evaluation of the pediatric surgical patientDocument Transcript
Evaluation of the Pediatric Surgical Patient
Complete care of the pediatric surgical patient includes establishing a good rapport with
the child, as well as the child's parents or guardian. Parents and guardians are often
anxious about the treatment of their child, and the responsibility to allay their fears lies
with the pediatric surgeon. Fostering a good relationship with the family can be
accomplished with skilled communication.
The surgeon should always thoroughly explain the child's problem. Reviewing the
results of imaging studies with the parents and patient is helpful. Freehand drawings
and diagrams from books can also be used to aid the surgeon in illustrating anatomy
and explaining the problem. Parents often gain a better understanding of their child's
problem if the surgeon takes the time to explain how or why the problem arose. Be
prepared to explain embryology in layperson's terms when talking to parents of patients
with congenital lesions and/or defects. Also be familiar with basic genetics and modes
of inheritance when counseling parents of a child with a genetic defect. Knowledge in
oncology is useful when discussing tumors; be prepared to answer general questions
regarding chemotherapy and radiation regimens for tumors commonly encountered in
pediatric surgery. Notify parents that the oncology staff is part of the team involved in
their child's care.
The explanation of the proposed surgery in layperson's terms includes describing where
the incision will be made, the steps of the surgery, how the incision will be closed, and
the size of the scar. At this time, basic postoperative issues can also be addressed,
including the anticipated length of hospital stay, the activity and dietary restrictions in
the postoperative period, and the time the child will likely be away from school. Explicitly
explaining why the surgery should be performed and what it should accomplish is
important. This is also the time to discuss the risks of surgery. In addition, discussing
options and alternative treatment plans is important. The consequences of not
performing surgery should be addressed as well.
Pause after providing important information so that parents have the opportunity to take
in all the information. Leave time for questions at the end of the encounter, and give
parents a means by which to contact you with questions. Refer parents to other
resources, such as support groups, the hospital's family resource center, and reliable
sources on the Internet. Caution parents with regard to the quality of information they
might find on the Internet because the accuracy of information varies widely.
The surgeon must obtain a complete and detailed history from the patient and parents.
The history, in concert with a well-performed physical examination, is the basis for a
diagnosis and treatment plan. In an academic setting, the attending surgeon often sees
the patient after a resident or medical student performs the initial evaluation. At this
time, the surgeon must verify important points in the reported history and findings. This
initial encounter with the surgeon also provides him or her with an opportunity to get to
know the child and family.
The chief complaint (CC) is the reason that the child presents to the pediatric surgery
service. Statement of the CC should always include the duration of symptoms. The
history of present illness (HPI) should detail the course of the symptoms, including its
acuity of onset, progression, and severity. Also include symptoms associated with the
child's CC. Document pertinent negative findings. Aggravating or relieving factors are
important and must be noted, as should any treatment the child has received. Any
medical or surgical history relevant to the CC should be stated in the HPI. Birth history,
medical conditions, and previous surgeries should be listed separately in the past
medical history (PMH) and past surgical history (PSH). Of importance, a history of
bleeding disorder or unusual bleeding should be noted, as well as any history of
Note the names, doses, and frequency of all medications that the child is currently
taking. Include medications that are taken on a schedule and those taken as needed.
Use of herbal supplements is increasingly popular, even in the pediatric population, and
they should be included in the list of medications. Note drug allergies and reactions,
along with symptoms that occur when the patient is given the drug. Food and
environmental allergens may also be listed.
Document the family history and the social history. For many pediatric surgical patients,
the family history is noncontributory. However, it is clinically significant in children with
congenital malformations, genetic diseases, or malignancies. A child's social history
should address issues regarding the family and home environment and the child's
academic and social development.
Conduct a thorough review of systems (ROS); list pertinent positives and negatives
already stated in the HPI.
The goal of the physical examination is to identify the current surgical issues and to
ensure that the organ systems other than the one being treated are healthy. Unlike the
adult physical examination in which one can often follow the same routine every time,
the pediatric examination must be modified for each patient. Interacting with children of
different ages and temperaments in different settings can be challenging.
Hand washing before and after performing the physical examination is essential. Hand
washing serves purposes more than infection control. On a psychological level, it
conveys a reassuring message to the parent that hygiene is important to the surgeon.
On a practical level, it warms the surgeon's hands before he or she touches the child.
In an older and cooperative child, physical examination can be performed by using a
standard routine. However, this routine may need to be modified in young children or
infants who do not cooperate.
Infants should be positioned on the examination table for the entire examination.
Toddlers and small children may sit in their parent's lap for the initial part of the
examination, and they can be moved to the examination table, and for the abdominal,
inguinal, genital, and rectal examinations, when required. Having the parent by the
examination table reduces the child's anxiety and should be encouraged.
Skin and integument
Always ask the patient to undress completely. The pediatric surgeon is often consulted
to evaluate lesions, or lumps and bumps. The lesion in question should be inspected for
its size, shape, consistency, circumscription, and mobility. Thoroughly search for other,
similar lesions on the body. Also inspect the skin for rashes, which may indicate an
infectious process or vasculitis. Scars indicating previous surgery should be noted.
Cellulitis may arise after any trauma that interrupts the skin barrier (eg, scratch,
laceration, foreign body, surgical wound). Erythema and warmth with induration and
fluctuance indicates an abscess. Inspect the skin for birthmarks, noting any changes in
their character. Bruises and burn scars, especially those resembling cigarette burns or
burns that have a well-defined shape, should be suspected as signs of child abuse.
Lymphadenopathy can occur in many locations, and often involves the cervical, axillary,
epitrochlear, or inguinal chains. In children, lymphadenopathy most commonly has an
infectious etiology, and a source of infection should be sought throughout the
examination. The infection may be bacterial, viral, fungal, or protozoal. Enlarged lymph
nodes may represent metastatic disease, or they may be the presenting sign of
malignancies, such as acute lymphoblastic leukemia (ALL), Hodgkin disease, and nonHodgkin lymphoma.
Head, ears, eyes, nose, and throat
On head, ears, eyes, nose, and throat (HEENT) examination, note the size and shape
of the patient's head. Children with abnormal fusion of the coronal sutures are not
normocephalic. Microcephaly or macrocephaly may indicate a neurologic or intracranial
process. An icteric sclera suggests hepatic or biliary dysfunction. Otitis media can be
excluded if tympanic membranes that are clear and if visible landmarks are found.
Finding an erythematous oropharynx or inflamed nasal turbinates with associated
rhinorrhea are common in upper respiratory tract infections. A quick dental examination
to identify loose teeth is important in children scheduled to undergo surgery.
Breast tissue is commonly observed in infant boys and girls. This is normal and due to a
slow decline in maternal hormones in the infant's bloodstream. On a similar note, the
pediatric surgeon may be asked to evaluate a male adolescent for gynecomastia, which
is often due to the changing hormonal environment associated with puberty. Evaluation
of breast masses in girls requires particular attention. In preadolescent girls, one must
distinguish a mass from a breast bud, keeping in mind that breast development does
not occur at the same rate in both breasts. Normal breast tissue must be differentiated
from a breast mass in female adolescents. The pediatric surgeon may also encounter
deformities in the chest wall, such as pectus excavatum and pectus carinatum. Apart
from discerning the degree of deformity, performing cardiac and pulmonary
examinations is important in children with these deformities.
Heart rate and rhythm should be noted on the cardiovascular examination. Many
children have an audible murmur at some point between infancy and adolescence. Most
murmurs fortunately occur in normal hearts and are benign. Murmurs that have a
structural cause may indicate a need for preoperative antibiotic prophylaxis. Consult a
cardiologist a new-onset murmur is in question. Check proximal and distal pulses.
Expect strong pulses throughout. Suspect coarctation of the aorta if pulses in the upper
extremity are strong but pulses in the lower extremity are weak or absent.
Good respiratory effort in a cooperative child is critical in the pulmonary examination. No
layers of clothing should be present between the stethoscope and skin. Breath sounds
should be clear on both sides. Abnormal breath sounds, such as rhonchi, wheezes, and
crackles, indicate an underlying pulmonary process.
The abdominal examination should be performed systematically and gently.
First, observe the patient's abdomen. If scars are present, their length and location can
give the surgeon an idea of the previous surgeries performed. The shape of the
abdomen may also be a clue to guide diagnosis. A scaphoid abdomen in a neonate or
infant may suggest a diaphragmatic hernia but may be normal in a thin child. Intestinal
obstruction, an abdominal mass, or ascitic fluid may cause abdominal distention.
Second, listen for bowel sounds. Be patient because up to 2 minutes may pass before
bowel sounds are heard. The absence of bowel sounds may suggest peritonitis. The
character of the bowel sounds is also important; high-pitched sounds are consistent with
While listening for bowel sounds in a young child, the clinician may use a stethoscope to
palpate the abdomen, systematically covering the entire abdomen. Begin the palpation
in an area away from the area of reported pain, leaving that area for last. Diffuse
tenderness may suggest peritonitis or a generalized process. Focal points of tenderness
often reflect the underlying pathology. Discern if the pain is superficial, musculoskeletal,
Gently evaluate the patient for peritoneal signs, such as rebound and guarding. Overly
aggressive examination creates unnecessary pain and fear in the child. In young
children, their facial expressions and behavior are often more reliable indicators of pain
than their verbal report. Palpation can also give the surgeon an idea of the size, shape,
and consistency of an abdominal mass. The size of the liver and spleen can be
determined by percussion and palpation of their edges.
The inguinal region is most commonly examined in the evaluation of a hernia or
hydrocele. If an inguinal hernia is not visible on examination, the child should be coaxed
to perform a Valsalva maneuver (eg, coughing or straining as during a bowel
movement). Intra-abdominal pressure is increased in crying infants. Hernias should be
easily reducible and not incarcerated or strangulated, which are surgical emergencies.
Children as young as 2 years understand the concept of modesty, and special attention
must be given to modesty during the genital examination. In addition, always ensure
that a staff person of the same sex as the patient is present in the room during the
Genital examination in boys is necessary in the evaluation of a number of conditions,
including hydroceles and undescended testes. Transillumination may be a useful
technique to visualize the contents of an enlarged scrotum but cannot be relied on for a
diagnosis, especially in infants. Note the size and shape of the testicle in the scrotal sac
and the character of any fluid. Part of the male genital examination includes checking
for the presence of both testes in the scrotal sac. The testis, epididymis, and spermatic
cord should be appreciated as separate structures. Retractile testes can masquerade
as undescended testes; always check to determine whether a testicle that is not in the
scrotum can be brought down into the scrotum. The genital examination is one of the
least comfortable parts of the physical examination; boys can assume the position most
comfortable for them—lying down, sitting frog-legged, or standing.
Performing a female genital examination to evaluate for fused labia, imperforate hymen,
vaginal or perineal bleeding, and an assortment of other issues is not uncommon. Note
that a pelvic examination performed by the surgeon is likely to be the first for a girl and
has lasting psychologic consequences. Always suspect sexual abuse when vaginal
tears are present. Vaginal discharge can be a sign of a sexually transmitted disease
and should raise the surgeon's index of suspicion for abuse.
The rectal examination may be traumatic to the child and their parents and should be
performed quickly but thoroughly. Explaining the process to the child is useful to assure
them that nothing will be done to them without first letting them know.
First, inspect the anus. Fissures, fistulas, skin tags, and other lesions can be seen by
gently separating the anal opening.
Next, inform the child that they will feel a finger on the outside. Gentle external pressure
often causes the anal sphincter to relax and facilitates passage into the anal canal.
Condyloma acuminata, caused by the human papillomavirus, are consistent with sexual
abuse. Always use water-soluble lubricant on a gloved finger and obtain a stool sample
for a guaiac test whenever feasible. The little finger may be used in infants and toddlers,
and the index finger may be used in larger children. Sphincter tone may be decreased
in patients who have previously undergone anoplasty or have sustained traumatic injury
to the sphincter muscle. Decreased sphincter tone is more alarming in the trauma
setting because it indicates spinal cord injury.
Palpate the entire circumferences of the anal canal and rectum. Note the location, size,
and texture of a palpated mass. Presacral tumors may be the cause of a child
presenting with constipation. The examiner must differentiate discomfort due to the
examination itself from tenderness due to an underlying process. Many children can
make this differentiation if asked. Pain on examination may be caused by anal fissures
externally, appendicitis in a low-lying appendix, or pelvic inflammatory disease. The
surgeon may also detect a fecal impaction during the rectal examination of a child with
Back and spine
Scoliosis and other spinal deformities are obvious during examinations of the back.
Vertebral tenderness to palpation may be a sign of trauma. Costovertebral angle
tenderness may be indicative of pyelonephritis or appendicitis in a patient with a
Clubbing is observed in many patients with chronic illness, especially patients who have
pulmonary disease. Cyanosis is an indicator of poor oxygenation or perfusion, and effort
should be made to determine whether the cyanosis is chronic or acute. Edema may be
a sign of impaired renal or cardiac function. Suspect abuse in patients with extremity
deformities secondary to long-bone fractures.
Much can be gained from observing a child's behavior. An interactive and playful child is
likely to have no focal neurologic findings on examination. However, a basic neurologic
examination, which only takes a minute with practice, should be performed regardless.
This comprises assessment of cranial nerve function, motor and sensory examination,
reflex evaluation, and cognitive assessment.
THE WELL CHILD
A number of pediatric surgical problems are found on routine physical examination by a
pediatrician or family physician. Children are then referred to the pediatric surgeon.
Evaluation of an otherwise healthy child should still include a discussion of the child's
health issues and a complete history and physical examination. Perform only the tests
that are to be used for diagnostic purposes. Routine preoperative laboratory tests and
chest radiography are not indicated for most children. Explain outpatient surgery and
details of nothing-by-mouth (NPO) status to parents. Advising parents that surgery may
be canceled in the event of upper respiratory tract symptoms or infection is wise.
Postponing hernia surgery in an infant with a severe diaper rash is reasonable. A repeat
history and thorough physical examination on the day of surgery is crucial; close
attention should be paid to the respiratory system and the surgical area. Clearly mark
the surgical site on the day of surgery.
THE PATIENT WITH TRAUMA
The history of a patient with trauma is often brief and aimed at identifying the
mechanism and circumstances surrounding the injury. Trauma can be divided by the
mechanism of injury into blunt and penetrating.
For blunt trauma, determining the mechanism and force of impact is important. Head
and extremity injuries are extremely common in children. Acceleration-deceleration
injuries commonly occur in motor vehicle accidents and falls from heights. Abdominal
organs most susceptible to injury include the liver, spleen, and fluid-filled loops of the
small bowel. Blunt trauma at low velocities causes compression injuries to the area of
trauma. These are often the liver or spleen in blunt abdominal trauma, fractures to the
ribs, and crush injuries to the extremities. Pulmonary contusions are also common.
Penetrating trauma may be accidental or nonaccidental. Knowledge of the impaling
object or weapon used is a crucial piece of information. For stab wounds and
impalement injuries, the size and length of the object should be documented. In gunshot
wounds, the amount of damage caused is related to the amount of energy the bullet
dissipated to the tissue in its trajectory. Therefore, the extent of injury can be gauged by
the caliber of the firearm used.
Other important information that may aid in assessment of the patient with trauma
includes the time of injury, the treatment received before arrival, the patient's other
symptoms, the character of pain, and the amount of blood loss. In addition, PMH and
PSH, medications, allergies, and immunization status, if available, may influence
management decisions. Also, note the time when the child last ate or drank.
Always keep the possibility of child abuse in mind. Have a high index of suspicion for
nonaccidental injury if the pattern of injuries is inconsistent with the described
mechanism or if several injuries of various chronicities are found.
Initial evaluation of the pediatric trauma patient should follow the well-known ABCDE
mnemonic for airway (with cervical-spine control), breathing, circulation, disability, and
exposure the American College of Surgeons recommends. The secondary survey
follows this initial assessment. Imaging studies may be indicated.
Remember that pediatric patients with trauma are anatomically and physiologically
different from adult patients with trauma.
Airway obstruction is the most rapidly lethal problem in the patient with trauma.
Situations in which airway protection are needed include (1) maintaining an airway in an
unresponsive patient, (2) protecting against aspiration, (3) preventing or reversing
hypoxia, and (4) providing hyperventilation to decrease intracranial pressure.
Provide supplemental oxygen to all patients with trauma. If the patient has any signs of
respiratory distress or inadequate ventilation, immediately secure and maintain the
airway. An intubated patient should also receive an orogastric or nasogastric tube for
decompression and to minimize risk of aspiration. Protect the cervical spine at all times.
When securing the airway, check to see that both lungs are ventilated. Ensure that
chest expansion is symmetrical and that breath sounds can be auscultated over both
lung fields. If an endotracheal tube was placed, listen over the stomach to ensure that
the esophageal intubation has not occurred. Examine the chest for sucking wounds, flail
chest, and subcutaneous emphysema.
Assess the presence and strength of pulses, skin color, capillary refill, and blood
pressure. Apply direct pressure to any visible hemorrhage.
Whenever possible, place 2 intravenous (IV) lines by using large-bore catheters. If
peripheral access is not possible, consider placing a central line or intraosseous line (in
children <6 y). Heart rate is a better indicator of impending circulatory collapse than
blood pressure because hypotension does not occur until 25-30% of the child's blood
volume is lost.
Warmed isotonic crystalloids such as isotonic sodium chloride solution and lactated
Ringer solution are the mainstays of fluid resuscitation. Administer an initial bolus of 20
mL/kg to treat shock. If the response is inadequate, this bolus may be repeated for a
total of 3 boluses. If the child is still hemodynamically unstable, use 10 mL/kg of packed
RBCs for resuscitation. If type-specific blood is not available, O-negative blood may be
administered. The patient may have signs of hypovolemic shock if fluid resuscitation
cannot keep up with hemorrhage.
Age-appropriate parameters are as follows:
Aged 0-6 months - Weight 3-6 kg, heart rate 160-180 bpm, systolic blood
pressure 60-80 mm Hg, respiratory rate 60 breaths per minute
Infant - Weight 12 kg, heart rate 160 bpm, systolic blood pressure 80 mm Hg,
respiratory rate 40 breaths per minute
Preschool aged - Weight 16 kg, heart rate 120 bpm, systolic blood pressure 90
mm Hg, respiratory rate 30 breaths per minute
Adolescent - Weight 35 kg, heart rate 100 bpm, systolic blood pressure 100 mm
Hg, respiratory rate 20 breaths per minute
Rapid neurologic examination should be performed in any child with trauma. The
Glasgow coma scale may be used in children; however, the verbal component must be
modified for children younger than 4 years, as shown below:
Appropriate words, social smile, fixes and follows - Verbal score of 5
Cries but is consolable - Verbal score of 4
Persistently irritable - Verbal score of 3
Restless, agitated - Verbal score of 2
None - Verbal score of 1
Assess the patient for movement of extremities. If the patient is comatose, check for
movement in response to noxious stimuli. Seek a sensory level if the patient is
cooperative. Note if the Babinski reflex is present. Do not sedate or paralyze the patient
until a good neurologic examination is performed (usually during the secondary survey).
The patient's clothing should be completely removed, and the entire body exposed. The
body surface area–to-weight ratio is higher in children than in adults. Blankets and
additional warming measures should be used to maintain the patient's body
temperature. Examine the patient for occult injuries, making sure that a log roll is
performed and the back is inspected for entry and exit wounds, vertebral deformities,
and tenderness. At this time, perform a rectal examination to evaluate for sphincter tone
and gross blood. Spinal precautions should be maintained, and movement of the patient
should be minimized until the cervical spine, chest, and pelvis are cleared.
The secondary survey, proceeding from head to toe, should follow initial assessment.
The HEENT examination focuses on facial lacerations and fractures, hemotympanum,
tympanic membrane rupture, CSF otorrhea, CSF rhinorrhea, epistaxis, septal
hematoma, loose teeth, and maxillary-mandibular malocclusion. A quick cranial-nerve
examination should include pupillary reactivity, extraocular movements, and facial
symmetry (eg, raising eyebrows). The neck examination is performed to identify areas
of tenderness, spinous process deformities, jugular venous distension, and tracheal
deviation. The chest should be palpated, and rib fractures identified. Evaluate for signs
of blunt or penetrating trauma. If not already identified in the primary survey,
pneumothorax, hemothorax, sucking wounds, and flail chest should be recognized at
this time. The abdominal examination includes auscultation of bowel sounds and
palpation to detect tenderness.
Always look for signs of blunt or penetrating trauma. Evaluate the pelvis for tenderness
and instability. Neurovascular assessment of the extremities and identification of
fractures, dislocations, and contusions should follow.
Despite careful primary and secondary surveys, 2-50% of injuries are still missed.
Missed injuries are more common in patients with a blunt mechanism injury than those
with a penetrating injury. A tertiary survey is therefore necessary and instrumental in
identifying all injuries. The tertiary survey identifies and catalogs all injuries and is
performed after the initial trauma resuscitation and operative intervention, typically
within 24 hours of injury. A repeat survey should be performed when the patient is
awake, responsive, and able to communicate at an age-appropriate level.
The tertiary survey involves:
Comprehensive review of the medical record (mechanism, pertinent
Repeat of primary and secondary surveys
Review of all laboratory data
Review of all radiographic studies with an attending radiologist
Focused abdominal sonography for trauma
Attempts to define the role of the focused abdominal sonography for trauma (FAST) in
pediatric trauma are ongoing. Thus far, the FAST appears to have the greatest utility in
a hemodynamically unstable patient with blunt abdominal trauma. In this group of
patients, FAST can potentially demonstrate the presence or absence of free
intraperitoneal fluid. However, as with any test, the quality of the study and
interpretation of the images is technician dependent, and the results should be
considered in this context.
Radiologic imaging: Radiographically assess the cervical spine by obtaining
anteroposterior (AP) and lateral views. Also obtain a chest AP view and pelvic images.
Obtain these images as early in the evaluation as possible, but do not delay attempts at
resuscitation. CT evaluation of the head is required if the patient has a history of loss of
consciousness, evidence of head injury on physical examination. Spinal MRI may be
needed to assess vertebral or spinal cord injury. Abdominal and pelvic CT is indicated if
abdominal tenderness or distension is present on examination, if the chest radiograph
depicts free air, or if intra-abdominal injury is a concern. Imaging of extremities and
other studies can be delayed until all potentially life-threatening conditions are excluded
In every patient with clinically significant trauma, order a complete blood cell count and
urinalysis. Additional tests, such as an electrolyte panel, a coagulation panel, and typing
and cross-matching may be indicated in selected patients. Serum transaminase,
amylase, and lipase levels may be helpful in evaluating abdominal injury. Hematuria can
be detected on urinalysis.
THE CHILD WITH ACUTE ILLNESS
Surgical evaluation and treatment of the child with acute illness is one of the most
challenging aspects of pediatric surgery. Patients with intra-abdominal catastrophes,
patients who have ingested foreign objects, and patients with trauma (addressed in the
section above) are in this category.
Physical examination of the child with acute illness is similar to that of the patient with
trauma. The child's airway must be secured and maintained, breathing must provide
adequate ventilation, and oxygenation, and circulation must adequately perfuse the end
Children with signs of hypovolemic shock are most commonly those with ongoing
hemorrhage, peritonitis, intestinal obstruction, burns, vomiting, or diarrhea. A patient in
hypovolemic shock should be resuscitated with a 20-mL/kg bolus of warm lactated
Ringer solution administered by means of peripheral or central venous line. If the child's
condition responds inadequately and if further resuscitation is necessary, the choice of
fluid (eg, crystalloid, colloid, blood) depends on the type of fluid that the child has lost. In
general, fluid lost because of burns, peritonitis, and bowel obstruction may be replaced
by lactated Ringer solution, which has an electrolyte composition similar to that of the
fluid lost from the intravascular space.
Acid-base imbalances and electrolyte disturbances must be corrected before surgery.
Electrolytes and arterial blood gases must be monitored serially until corrected and
Adequate volume resuscitation is crucial because anesthetic agents cause vasodilation.
Therefore, patients with hypovolemia can have sudden hypotension with possible endorgan damage if they undergo anesthesia before receiving sufficient resuscitation. The
endpoint for volume resuscitation includes improvement in skin color and capillary refill
and adequate urine output (1 mL/kg/h measured by using a urinary catheter).
THE CHILD WITH CHRONIC ILLNESS
Treating a child with chronic illness creates a unique set of challenges for the pediatric
surgeon. These children tend to be deconditioned, and they often have several medical
problems that require careful attention before surgery. Depression, malnutrition,
anemia, and growth retardation are all characteristic findings in these children. In
addition, some children are immunocompromised or have coagulopathies as a result of
their illness or medical therapy.
Whenever possible, children with chronic illnesses should be brought to their individual
optimum level of health before undergoing a surgical procedure. Malnourished children
can be fed a high-calorie diet, or their tube feedings can be increased. The target
plasma protein concentration is 5 g/dL. Children with chronic disorders or renal disease
often have associated anemia with usual hemoglobin concentrations of 6-9 g/dL. Target
preoperative hemoglobin values should be individualized to the type of procedure
planned and to the outcomes of a discussion with the anesthesiologist. Coagulopathies
and electrolyte derangements must be corrected before surgery. Features of various
chronic illnesses that require special attention are elaborated below.
Before surgery, blood glucose levels should be closely monitored in patients with
diabetes mellitus, especially during the fasting. Hyperglycemia or hypoglycemia can be
corrected with insulin or with the addition of dextrose to IV fluids, respectively. Patients
taking regimens of short- and intermediate-acting insulin should continue this regimen
until the morning of surgery. Patients who take long-acting insulin may receive
intermediate-acting insulin the evening before surgery. If a patient is taking a
complicated insulin regimen or if he or she has an insulin pump, consulting an
endocrinologist regarding preoperative and postoperative care is prudent.
With rates of obesity steadily on the rise and reaching epidemic proportions, the
pediatric surgeon is encountering the obese patient with increasing frequency. Obese
patients have an increased incidence of medical comorbidities, including glucose
intolerance, diabetes mellitus, hypertension, hyperlipidemia, nonalcoholic
steatohepatitis, obstructive sleep apnea, deep vein thrombosis, and pulmonary
embolism. These conditions must be taken into account in the preoperative workup of a
patient undergoing surgery.
Additional concerns are limitations regarding radiographic evaluation in obese patients.
Weight limites for tables used to perform CT, MRI, and angiography are 250-450 lbs.
and vary by the manufacturer. Sizes of gantries and patient compartments also vary.
Alternative methods of evaluation must be sought if the patient's size exceeds the
capacity of the machine.
To minimize the risk of bacterial endocarditis, children with congenital heart disease,
prosthetic valves or patches, valvular prolapse, and valvular insufficiency should be
given antibiotic prophylaxis before surgery of the GI, GU, or respiratory tract. In GI and
GU surgery, ampicillin and gentamicin are the recommended regimen unless the patient
has a penicillin allergy, in which case, vancomycin and gentamicin are recommended.
Patients undergoing respiratory tract surgery require ampicillin prophylaxis.
Cephalosporins, clindamycin, azithromycin, or clarithromycin may be used in patients
with a penicillin allergy.
For patients who have a complicated heart condition, the pediatric surgeon should
communicate with the pediatric cardiologist before surgery. Close electrolyte monitoring
is required for patients taking diuretics. Patients taking digitalis must be carefully
observed for digitalis toxicity. The patient's intake and output must be strictly recorded,
and the surgeon should watch for signs of heart failure.
Common pulmonary diseases encountered by the pediatric surgeon include asthma and
cystic fibrosis. Patients with asthma should be preoperatively asymptomatic; to resolve
symptoms, pharmacologic, environmental, and/or dietary control may be needed.
Patients should continue their medications during the preoperative period. Patients with
cystic fibrosis are often deconditioned, and the pediatric surgeon should work in concert
with the pulmonologist to optimize the patient's health before surgery to minimize the
surgical risk. Hyaline membrane disease is a common problem in the neonatal
population, and patients with this disease may develop bronchopulmonary dysplasia,
which increases the risk of atelectasis and carbon dioxide retention. Chest radiography
is routine for all patients with pulmonary disease.
Chronic liver disease can result from biliary atresia, cystic fibrosis, hepatitis of any
etiology, or liver injury. If edema or ascites is present, the patient should be given
diuretics and be on a sodium-restricted diet. In children with a history of any of these
conditions, determine liver enzyme levels and perform coagulation tests before surgery.
If a coagulopathy is present, administer vitamin K and fresh-frozen plasma (FFP)
preoperatively and ensure that FFP is available in the operating room. Be careful when
prescribing drugs that are metabolized and excreted by the liver; monitoring of serum
drug levels is essential.
Renal function can be easily assessed by performing urinalysis and obtaining serum
blood urea nitrogen (BUN) and creatinine levels. The fluid and electrolyte balance is
often tenuous in patients with renal disease. Pay careful attention to the patient's intake
and output. Patients with difficulty concentrating urine often have increased fluid and
salt intake to compensate for increased urine output. Closely monitor these patients
during the fasting period before surgery because they can become dehydrated quickly.
In such patients, securing peripheral IV access is always sensible, even before surgery.
Electrolyte monitoring is important in the preoperative period, and any acid-base
imbalances and electrolyte disturbances must be corrected before surgery.
In its advanced stage, renal failure is manifested by hyperkalemia, hyperphosphatemia,
and acidosis. Patients with renal failure require immediate attention. Be careful when
prescribing drugs that are metabolized and excreted by the kidney; monitoring of serum
drug levels is essential.
HIV infection in pediatric patients is often associated with medical manifestations such
as failure to thrive, persistent lymphadenopathy, oral candidiasis, chronic parotitis,
chronic cough, and generalized dermatitis. The surgical manifestations in pediatric
patients with HIV or AIDS are less often discussed. Patients with HIV who come to the
attention of surgeons often have infections and may be severely septic with
opportunistic pathogens. Prompt recognition and treatment of the surgical problem is
essential. Outcomes are improved when antiretroviral medications are used. Close
consultation with pediatric immunodeficiency specialists is warranted in the
management of pediatric patients with HIV who have a surgical problem.
Patients who have an isolated surgical problem and who are otherwise healthy do not
require routine laboratory tests before surgery. In patients with other medical problems
and those undergoing major operations, order a complete blood cell count, electrolyte
tests, and coagulation studies. If clinically significant blood loss is anticipated, the
patient's blood should be typed and screened or cross-matched so that blood can be
immediately available if needed in the operating room.
Establishing NPO status
Anesthesia carries an inherent risk of the patient's vomiting and aspirating the stomach
contents. NPO status should be discussed with the anesthesia team and assigned
according to the guidelines and policies of the individual institution.
General guidelines are as follows:
Solids or formula: Newborns and infants younger than 6 months should be
assigned NPO status for 4 hours before surgery. Patients older than 6 months
should be NPO for 6 hours before surgery.
Clear liquids: All patients should be NPO for 3 hours before surgery.
Always consult the anesthesia team before complicated and unusual operations. These
include procedures that involve repositioning the patient during the operation or
manipulation of the great vessels or lungs. Notify the anesthesia team if the patient has
a history of complications with previous anesthetics, malignant hyperthermia, or a
Also, alert the anesthesia team if the patient has symptoms of an upper respiratory tract
illness because this increases the risk of postintubation laryngotracheal edema.
Preoperatively notify the anesthesia team about patients who might benefit from a
caudal injection or an epidural catheter insertion for postoperative pain control.
Preoperative pain consultation is appropriate if clinically significant postoperative pain is
anticipated. The pain-management team can then proactively discuss postoperative
pain treatment options with the family. In deciding whether to proceed with or cancel an
operation, deferring to the anesthesiologists is always prudent.
Condition the patient's current medications. Patients who have been taking
corticosteroids long-term may not be able to mount a natural stress response because
of chronic suppression of the hypothalamic-pituitary-adrenal axis. During the
perioperative period, these patients should receive stress dosing of corticosteroids
proportional to the stress of surgery.
Patients who are taking antihypertensives should continue them but must be closely
monitored for intraoperative hypotension.
Other drugs that should be continued in the perioperative period include antiepileptics,
drugs for asthma, and immunosuppressants. Drugs that should be discontinued before
surgery include anticoagulants, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs),
Regarding preoperative medications, bowel-preparation guidelines are as follows:
Administer polyethylene glycol-electrolyte solution (GoLYTELY) 50 mL/kg by
mouth (PO) or by means of a nasogastric (NG) tube or gastrostomy tubes (GT).
If the bowel is not clear after 4 hours, administer an additional 25 mL/kg.
Administer 5% dextrose in 0.2% sodium chloride solution plus potassium chloride
(KCl) 20 mEq per liter IV as a maintenance fluid.
After the polyethylene glycol-electrolyte solution is given, administer neomycin
and erythromycin (E.E.S.) base, each at a dose of 15 mg/kg PO every 90
minutes for 3 doses.
If necessary, administer 2 doses of 1% neomycin enema per rectum (PR) or
through a stoma or mucous fistula when the polyethylene glycol-electrolyte
solution clears the bowel. For the neomycin enema, administer 10 mL/kg in
infants, 100-150 mL in small children, 150-200 mL in large children, and 200-300
mL in adolescents.
Consider sedation. Patients who are unusually anxious in the immediate preoperative
period may be given sedation with midazolam.
Obtaining consent from a parent or guardian for a procedure requires the clinician to
discuss the indication for the procedure, describe the procedure, explain alternatives to
the procedure, and declare the potential risks and complications. Bleeding and infection
must always be mentioned, along with any other risks inherent to the surgery being
performed. When appropriate, involve the child in the discussion of the surgery and the
consent process. Be sure that the child has an age-appropriate understanding of why
the surgery must be done and what participation it involves on his or her part. Children
are often curious and may have questions and concerns, which should be addressed
Ethical and legal pitfalls.
The pediatric surgeon works at the juncture between surgery and pediatrics and,
consequently, must deal with the surgical, medical, and ethical issues that concern both
areas. Unique new challenges as well as ancient traditions in medicine can influence
the pediatric surgeon's approach to ethical dilemmas.
Historically, the Hippocratic oath defined the ethical principles guiding medicine,
instructing physicians to use their knowledge and skills for the benefit of their patients
and to protect their patients from harm. This tradition did not define a role for the patient,
surrogate, or parents in the decision-making process. Consequently, a collaborative
process has evolved, incorporating the ethical principles of patient autonomy, respect
for persons, nonmaleficence, beneficence, and justice. In this model the physician
contributes medical knowledge, skill, and judgment; the patient or the patient advocate
contributes a personal evaluation of the potential benefits and risks inherent in the
Physicians enter a professional relationship with a pediatric patient by one of two
routes, either electively or emergently. Usually, a parent or guardian of a child makes an
appointment to see a physician about a medical problem, and the physician agrees to
provide treatment in exchange for compensation. Alternatively, surgeons, as emergency
call physicians, may encounter situations in which care must be rendered without a prior
relationship. In such cases, a surgeon may need to operate on a pediatric trauma
patient without informed consent from the parent.
Responsibilities in emergent care
If a children's hospital or a hospital with pediatric expertise represents itself as operating
an emergency department or a trauma center for children, that hospital has several
legal duties that reflect its ethical responsibilities, including the following:
A duty to accept and treat all patients coming to the emergency department
A duty to provide a properly equipped facility
A duty to ensure that competent medical care is provided to each patient
Once treatment is undertaken, the surgeon may not unilaterally terminate the legal
relationship unless or until one of the following conditions is met:
Care is no longer needed.
The parent or surrogate agrees to the termination of care.
Appropriate transfer of care has been carried out.
Responsibilities found in the routine care of pediatric surgery patients do not vary
greatly from those of other pediatric patients, or indeed patients in general. The same
ethical principles that guide all decision-making are pertinent, with attention to the
special circumstances in the care of children. Thus, the obligation exists for
nonmaleficence, ie, "in the first place, we should do no harm."
The physician's professional obligation to place the patient's interest before his own
may be sorely tested in the care of children, not only by the large number of
underserved and uninsured patients in the field, but also by occasional difficulties in
agreeing on what the child's best interest may be.
Parents are allowed considerable latitude for medical decisions on behalf of their
children, and the law protects the natural rights of parents to raise children free from
unwanted interference. The presumption is that parents act in the best interests of their
children and these rights are conditional on parental fulfillment of the duty to provide
necessary care for minor children.
In respecting patient autonomy and self-determination, physicians must obtain informed
consent from a parent or surrogate before a child can undergo medical interventions,
other than in the case of emergencies. As a component of informed consent, the
surgeon must consider and discuss with the family the risks and benefits involved with
each surgical procedure.
Truly informed decisions require that parents or surrogates receive and understand
accurate information about their child's condition and prognosis, the nature of the
proposed intervention, the alternatives, and the risks and benefits. Parents or
surrogates must be able to do the following:
To deliberate and choose among alternatives
To ask questions to their satisfaction
To be able to relate the decision to a personal and stable framework of values
To make decisions free of undue coercion
Informed consent in children presents special problems, both philosophically and
legally. In the United States, adult patients are presumed to have decision-making
capacity unless a court of law has declared them incompetent to make such decisions.
Children are persons in the social sense and they have rights, but they are not judged
legally competent to make decisions about their medical treatments until they reach the
age of majority, ie, 18 years. Therefore, children cannot give consent for themselves,
but they can assent to procedures, either indirectly (by their acquiescence) or directly
when they are involved in the discussion.
Because nothing miraculous happens on an 18th birthday to make a person a mature
adult, it is a legal status only. Many young people can make morally mature decisions
before they are legally entitled to do so. Therefore, older children and adolescents
should be included in the decision-making process (patient assent), depending on their
neurologic status, development, and level of maturity; however, legally, they require a
surrogate decision-maker to act on their behalf (ie, parental permission). What parents
actually do, therefore, is give permission for a treatment or surgery on their child; only a
competent, fully autonomous individual is capable of giving consent, and then only for
Conflicts of interest or religious preferences may lead parents to make decisions that
may not be in the perceived best interests of the child. The children of Jehovah's
Witnesses, particularly those who require an operative procedure that is associated with
a risk of significant blood loss, are best considered in a distinct consent process that
incorporates the religious views but upholds the rights of the child.
When a child is brought to an emergency department by prehospital care providers, no
parent is in attendance, and the child needs emergency treatment or surgery, most
hospitals and operating rooms allow treatment to be initiated under the theory of implied
consent for emergency treatment. Aggressive attempts should be made by emergency
department personnel to locate the child's parent(s) or guardian, but life-saving
maneuvers, including surgical procedures, should not be withheld. Under the
circumstance of need for urgent surgery, an institutional requirement may be in place for
two or more physicians, generally those who are not involved in the technical
procedure, to sign a consent form on behalf of the child, indicating their agreement that
a true emergency exists and the proposed surgery is warranted.
Children of divorced parents
Many parents are divorced, and custodial arrangements for their child may be complex.
If a child's parents are divorced, the custodial parent usually has the authority to make
medical decisions on behalf of the child. For new pediatric patients coming to the clinic
or office, registration forms should denote with whom the child lives and who has legal
custody. At times, the custodial parent may indicate a desire to limit visitation or
provision of information to a noncustodial parent.
Antagonistic parental relationships may interfere with the physician's ability to render
appropriate care to the child. Examining written divorce settlements may be necessary
to determine what is legally appropriate. These tasks can be delegated to a member of
the hospital legal department if necessary. Unfortunately, a parent may occasionally
become offensive, abusive, or aggressive, and the security services of the hospital may
have to be involved and/or visitation privileges may have to be restricted or rescinded.
Neonates with major malformations
Baby Doe cases involve decisions by physicians and parents to withhold life-sustaining
treatment from severely handicapped or critically ill newborns. The name was given to
legal cases in which babies with Down syndrome or spinal bifida required surgeries, but
their parents refused consent. These resulted in court challenges, executive rulings, and
congressional action. At times these solutions were highly intrusive, even requiring the
posting of hot-line numbers in the NICU for the use of anyone who was concerned that
infants were being denied necessary care.
Treatment may be withheld from neonates under the following conditions:
The infant is chronically and irreversibly comatose.
Treatment merely would prolong dying or would not be effective in ameliorating
or correcting all the infant's life-threatening conditions.
Treatment would be virtually futile in terms of survival and, therefore, inhumane.
Neonatologists differ in their opinions regarding whether these guidelines lead to
excessive treatment of infants who are hopelessly ill. The main ethical dilemma in these
complex cases involves balancing the benefits of prolonging life through the use of
multiple invasive medical and surgical procedures against the potential burden on the
child and family.
Do-not-resuscitate (DNR) is the traditional order given for an individual who should not
receive cardiopulmonary resuscitation (CPR) in the event of a cardiopulmonary arrest.
This term suggests that resuscitation would be successful if undertaken. The term donot-attempt-resuscitation (DNAR) may be a clearer indication that success at
resuscitation is often not achieved.
DNAR orders are written for children when an attempt to resuscitate would not benefit
the child and if the parent or surrogate expresses his or her preference that CPR be
withheld in the event that the child experiences a cardiopulmonary arrest, provided this
is in the child's best interest.
The American Heart Association has recently issued new guidelines for withholding
CPR. A special circumstance for the pediatric surgeon involves the newly born child
with certain chromosomal or anatomic defects with a uniformly poor prognosis or
extreme prematurity. For the newly born, antenatal information about gestational age or
congenital anomalies may be uncertain, and prediction of outcome may not be possible
or accurate. In these cases, a trial of therapy and additional assessment of the infant
may allow the surgeon to better assess diagnostic and prognostic data for family
counseling and allow better-informed discussions about continuation or withdrawal of
However, current data support the belief that resuscitation of infants with extremely low
birth weight (<23 wk or <400 g) with certain chromosomal or anatomical defects is
unlikely to result in survival or in survival without extreme disability. This constitutes
quantitative or qualitative futility, and noninitiation of resuscitation in the delivery room is
Family presence during invasive procedures and CPR
A growing body of literature exists concerning the topic of family presence during
invasive procedures and CPR. The Emergency Nurses Association (ENA) first
developed family presence guidelines in 1995 and later revised them in 2001. Health
care providers have expressed a variety of concerns regarding family presence,
including the concern that it has the potential to interrupt or hinder patient care or to
predispose members of the team to litigation if the family perceives that mistakes or
wrong decisions have been made.
Conversely, studies indicate that most family members want to be at the bedside. In
cases when the patient dies, family presence removes the family's doubts and
reassures that everything possible was done for their loved one; their presence
facilitates grief and does not disrupt the actions of the medical team.
Few formal studies have been performed in pediatric patients. Those that are available
indicate that children prefer to have parents present both for the emotional support and
to help them cope with pain during invasive procedures. Similar arguments support the
presence of parents with their children until preoperative anesthesia is fully induced.
Death by neurologic criteria (brain death)
Cardiopulmonary support systems may be withdrawn from patients with brain death
without fear of legal repercussions
Organ and tissue recovery
Patients who meet neurologic criteria for death may be appropriate candidates for organ
or tissue recovery. In cases in which CPR is unsuccessful, tissue donation is possible.
The shortage of recoverable organs has led to the enactment of required request laws,
requiring documentation that families of potential donors are offered the option of organ
and tissue donation and that the local organ procurement organization is notified of all
potential donors. The declaration of brain death in cases of child abuse does not
preclude the option of organ or tissue donation.
Practicing resuscitation skills on the newly dead
The use of newly dead patients for research and training raises ethical and legal issues.
Obtaining consent of family members is ideal and respectful of the newly dead.
Relevant procedures applicable to infants and children include placement of an
endotracheal tube and vascular access procedures. This practice has the potential to be
brief, beneficial to others, and an effective teaching technique. However, the cultural
and emotional issues of family and staff may influence the suitability of this practice in a
The Fetus as a Patient: Prenatal Diagnosis and Fetal
Only in the past few decades has the fetus been considered a patient and become the
subject of extensive scientific study and attempts at treatment. Fetal medicine is a
complex multidisciplinary undertaking with a team consisting of the following:
An obstetrician, who manages the pregnancy and performs many minimally
invasive interventions such as percutaneous shunt and catheter placement
A perinatologist or geneticist, who focuses on prenatal diagnosis, prognosis,
genetic counseling, and the procedures involved in prenatal diagnosis
A neonatologist or pediatric surgeon, who is responsible for the continued
postnatal management of the fetus' disease process and formulates the fetal
An obstetric sonologist who has expertise in defining the fetal diagnosis and its
severity and guiding diagnostic and therapeutic procedures
Specialists, such as cardiologists, neurologists, and urologists, depending on the
Many problems are of particular significance to fetal medicine.
Unclear team leadership: The physician who takes responsibility for a particular
procedure may be different from the one who made the diagnosis or the team
taking care of the mother.
Inadequate traditional roles and skills: The obstetrician may find that closing an
empty uterus is entirely different from closing a gravid uterus. Surgeons who are
accustomed to excising the posterior urethral valves in the neonate may find the
same procedure difficult to perform in a half-exteriorized fetus.
Incompletely resolved issues: These include the optimal agent and depth of
anesthesia for both the fetus and mother and the best methods to control
bleeding, maintain fetal exposure, monitor both patients, prevent preterm labor,
and prevent the leak of amniotic fluid.
Prenatal diagnosis of fetal disorders and structural malformations is becoming
increasingly important for several reasons. Approximately 3% of all pregnancies result
in the delivery of an infant with a genetic disorder or birth defect. Such anomalies are
also the biggest cause of infant mortality in the United States. Minor malformations are
found in an additional 7-8% of neonates.
Over the last 4 decades, the genetic basis of an increasing number of diseases is
becoming understood. At the same time, safe and effective fetal diagnostic techniques
are being developed. The advantage of prenatal diagnosis of fetal malformations is that
genetic counseling can be provided. In addition, the parents, obstetrician, geneticist,
and other specialists can discuss options ranging from abortion to intrauterine medical
and surgical treatments. The optimal time, mode, and place of delivery can be
determined, and a postnatal treatment plan can be formulated.
Screening tests are safe, less-invasive tests performed on a large, relatively low-risk
population in whom diagnostic tests are required to confirm the diagnosis. These test
results can modify risk perception, and a positive screening test result is a stronger
indication for invasive procedures such as amniocentesis. The tests screen for
chromosomal anomalies and neural tube defects. They are also performed in mothers
with a high-risk ethnic background for genetic diseases, such as Tay-Sachs disease in
Ashkenazi Jews and α- and β-thalassemias in those of Mediterranean and Southeast
Maternal serum alpha-fetoprotein test
Maternal serum alpha-fetoprotein (AFP) levels at 16-20 weeks' gestation are used to
screen for open neural tube defects. The implications of an elevated AFP level vary with
gestation, as well as with maternal weight and race. If an elevated AFP level is found,
the test is followed by a targeted ultrasound and, perhaps, amniocentesis to distinguish
among the possible etiologies.
Causes of an elevated maternal serum AFP level include the following:
Neural tube defects
Open abdominal wall defects
Renal diseases such as congenital nephrosis, infantile polycystic disease, and
bilateral renal agenesis
Skin diseases such as ectodermal dysplasia and aplasia cutis congenita
Cystic adenomatoid malformation of the lung
Maternal hepatic and ovarian tumors
Uterine and placental anomalies
Causes of low maternal serum AFP levels include the following:
Insulin-dependent diabetes mellitus in the mother
The triple-panel test
The panel includes maternal serum AFP, serum β-human chorionic gonadotropin (βHCG), and unconjugated estriol. The panel, along with maternal age, is a more
sensitive (60-91%) screen for fetal aneuploidy. Maternal weight, race, and multiple
pregnancies may affect the risk calculation. In a fetus with Down syndrome, β-HCG
levels are elevated, and the other two levels are decreased. The triple panel can detect
57-67% of fetuses with Down syndrome in women younger than 35 years and 87% in
Maternal hexosaminidase test
Maternal hexosaminidase levels increase in pregnancy and reflect a fetal origin. In a
high-risk mother, persistent prepregnancy levels can indicate a fetus with the deficiency
of the enzyme, as can occur in Tay-Sachs disease.
Pregnancy-associated plasma protein A test
Pregnancy-associated plasma protein A (PAPP-A) and free α-human chorionic
gonadotropin (α-HCG), along with ultrasonographic markers in the first trimester, have a
sensitivity of 80% and a high specificity in the detection of Down syndrome in the fetus.
Diagnosis-directed tests are invasive and pose some risk to the mother and fetus, but
they directly analyze the fetal material and confirm the diagnosis. Special circumstances
indicate the use of these tests, which are not screening tests.
Indications for Diagnostic Tests
Conditions that increase the risk of chromosomal anomaly include the following:
Advanced maternal age (>35 y), the most common indication
Previous offspring with chromosomal anomalies or other birth defects
Parental balanced translocation, inversion (manifests as recurrent pregnancy
loss), or both
Suggestive fetal ultrasonographic findings
Positive maternal screening test findings
Mother having a disease or being exposed to drugs, medications, or infections
known to be associated with congenital malformations in the fetus
Mendelian genetic trait in the parents
Molecular DNA diagnosis (cystic fibrosis, homozygous hemoglobin sickle disease
[HbSS], fragile X)
Enzymatic activities in villi, amniocytes, or both (Tay-Sachs disease, Refsum
Precursor levels in cell-free amniotic fluid (17-OH-progesterone in congenital
As a prerequisite and as follow-up to prenatal diagnosis, families must be informed
about the diagnosis, severity, prognosis, and available options for treatment and
continuation of pregnancy.
Chorionic villous sampling
Chorionic villous sampling (CVS) is the technique of choice for prenatal diagnosis prior
to 12 weeks' gestation for detection of a chromosomal anomaly, DNA molecular
diagnosis of classic genetic disorders, and the detection of defects in lysosomal
enzymes or mucopolysaccharidoses. A diagnosis of enzymatic defects, such as 21hydroxylase deficiency that causes congenital adrenal hyperplasia, can be made with
an allele-specific amplification analysis technique of DNA obtained with CVS.
A preliminary ultrasound is performed to establish fetal viability, gestation, and anatomy
and to determine the placental location. A sample of placental tissue is obtained using a
16-gauge polyethylene catheter for analysis under ultrasonographic guidance. The test
is usually performed at 8-12 weeks' gestation.
The approach is based on the placental location. A transabdominal approach is
preferred for anterior and fundal placentas after 13 weeks' gestation and in active
vaginal and cervical infections. The sample is smaller than that obtained with the
transcervical method. The transcervical approach is indicated in cases with interposed
bowel loops or uterine retroversion and a posterior or low-lying placenta. The
transvaginal approach has limited application and is used when the placenta is placed
posteriorly, the uterus is retroverted and retroflexed, and the cervical canal points
towards the abdomen.
Chromosomal analysis of the sample is performed in 2 ways. The direct method
evaluates the metaphysis from the outer layer of cytotrophoblasts in the chorionic villi.
This method provides results in 2 days. A long-term culture of the inner mesenchymal
layer of trophoblasts provides results in 10-14 days. These results more closely
correlate with the true karyotype.
An abnormal direct result has to be confirmed with long-term cultures of trophoblasts,
amniotic cells, or fetal lymphocytes. Rarely, a normal direct result is followed by
abnormal culture findings, which are confirmed with fetal tissue results. Chromosomal
mosaicism occurs in 1.2-2.5% of the samples and may cause diagnostic error. The
mosaicism is purely extraembryonic in 70-80% of the cases, and it is more common in
direct preparations. If found in both direct preparation and long-term cultures, a followup ultrasonographic level 2 screening for anomalies and amniocentesis or
cordocentesis are indicated to verify mosaicism in the fetal blood. Maternal cell
contamination may also distort the results.
Complications associated with CVS include the following:
Pregnancy loss is 0.6-0.8% more common than the natural pregnancy loss rate
in the first trimester and more common that the rate in midtrimester
amniocentesis. Limb reduction defects and oromandibular malformations are
more likely in some studies, especially if the procedure is performed prior to 10
Fetomaternal transfusion can occur regardless of the approach used. Thus, Rh
isoimmunization is considered a relative contraindication, and Rh
immunoprophylaxis is administered to Rh-negative women after the procedure.
This technique, performed at 12-14 weeks' gestation, assists in the diagnosis of
chromosomal anomalies by providing fetal cells for karyotyping. It can also lead to the
diagnosis of structural anomalies such as neural tube defects and omphalocele through
the measurement of AFP and acetylcholinesterase levels. It is preferred to CVS in
situations in which CVS is not reliable, such as twin pregnancy with fused placentae and
in certain biochemical disorders.
The procedure consists of the aspiration of amniotic fluid (approximately 1 mL/wk of
gestation) from an amniotic fluid pocket with a 22-gauge needle and ultrasonographic
Complications associated with amniocentesis include uterine bleeding (1.9%), uterine
cramping, leakage of amniotic fluid (2.9%), pregnancy loss (1.4-4.2%), increased risk of
club foot when performed prior to 12 weeks' gestation, failed procedure due to tenting of
the membranes ahead of the needle, and culture failure rates of 1% overall and 5% if
the procedure is performed prior to 12 weeks' gestation. Pseudomosaicism and
maternal contamination are less likely than with CVS.
This controversial procedure is performed for preimplantation diagnosis in a fetus of
parents with substantial risk of a known genetic disorder and in women with repeated
miscarriages due to chromosomal translocation.
At the 8-cell stage of the embryo, a single cell is removed and analyzed (blastomere
biopsy) for X-linked recessive diseases. Only XX embryos are transferred following in
vitro fertilization. More trophectodermal cells can be removed from the blastocyst for
analysis. Because it has the same genetic constitution as the ovum, the second polar
body can also be analyzed for diseases with known gene defects such as cystic fibrosis,
hemophilia, and α1-antitrypsin deficiency.
Coelocentesis, defined as coelomic fluid aspiration, can be performed as early as 6-10
weeks' gestation but is still considered investigational because of the high rate of
pregnancy loss reported.
Fetal cells from maternal blood
The isolation and analysis of nucleated fetal cells from maternal blood is a novel
noninvasive technique of prenatal diagnosis of chromosomal aneuploidies. A direct
micromanipulator isolation of histochemically identified fetal hemoglobin (HbF)–positive
nucleated red cells is followed by fluorescent in situ hybridization (FISH) analysis for
chromosomal aneuploidies. The results are obtained in 72 hours and correlate highly
with amniocentesis results.
Diagnostic Tests in the Second Trimester
Amniocentesis performed at 16-18 weeks' gestation is the criterion standard of prenatal
diagnostic techniques in both efficacy and safety. It is offered to all women older than 35
years or with an elevated serum AFP level. Genetic counseling to evaluate genetic risks
and detailed ultrasonography to estimate gestation, placental location, and amount of
amniotic fluid are important prior to the procedure.
The procedure is the same as that of amniocentesis in early gestation, except that 2030 mL of amniotic fluid is aspirated for analysis.
The amniotic fluid phase can be analyzed for several substances.
AFP and acetylcholinesterase levels are used to identify a fetus with a neural
tube defect, with 98% sensitivity.
Bilirubin levels in amniotic fluid are elevated in isoimmune hemolysis, and the risk
to the fetus can be predicted based on the bilirubin level and gestational age.
Pulmonary surfactant and surface-active phospholipids are measured in amniotic
fluid to evaluate fetal pulmonary maturity. A lecithin-to-sphingomyelin ratio of
greater than 2, as measured chromatographically in a noncontaminated sample,
suggests lung maturity, except in fetuses of mothers with diabetes. Other fetal
lung maturity assays measure the surfactant-to-albumin ratio with fluorescent
polarization technology and provide early results. Both of these tests are affected
by contamination with blood or meconium, and results are unreliable in fetuses of
mothers with diabetes or preeclampsia or in cases of intrauterine asphyxia. The
presence of phosphatidyl glycerol in amniotic fluid indicates lung maturity,
particularly in fetuses of mothers with diabetes. Saturated phosphatidylcholine is
unaffected by contamination with blood. A combination of these tests provides a
more accurate indication of lung maturity.
Enzyme analysis and measurement of metabolite levels, used for the diagnosis
of urea cycle disorders and of other inborn errors of metabolism, may also be
performed on the amniotic fluid at this stage.
Fetal cells can be extracted from amniotic fluid samples and analyzed for the following
chromosomal and genetic disorders:
Chromosome analysis through direct metaphase visualization is the traditional
method; results are obtained in 1-2 weeks. FISH, when used in addition to
standard cytogenetics, can analyze fetal cells for abnormalities in chromosomes
21, 18, 13, X, and Y and provide results in 48-72 hours. FISH can also detect
microdeletions found in Prader-Willi, DiGeorge, Williams, and Angelman
Direct DNA analysis is done with polymerase chain reaction (PCR) gene
amplification, followed by Southern blot analysis to detect gene deletions. Allelespecific oligonucleotide (ASO) analysis measures the specific binding of labeled
probes to normal DNA or mutant sequences to detect gene mutations. This
technique is important in identifying disorders in which multiple mutations have to
be screened for, such as cystic fibrosis and thalassemia, or in which a restriction
site is not created, such as Duchenne muscular dystrophy, Tay-Sachs disease,
Indirect DNA methods, such as linkage analysis with restriction fragment length
polymorphisms (RFLPs), are performed in affected individuals and multiple other
family members. This can help in making the diagnosis of diseases in which the
exact gene defect and location are not known. Cross-over changes between the
gene and the RFLP probe can distort the results. Survival motor neuron (SMN)
analysis for gene deletion in the family of an affected patient is useful in the
prenatal diagnosis of spinal muscular atrophy. Molecular analysis of the fibroblast
growth factor receptor 3 gene with direct and restriction enzyme analysis can
help to diagnose thanatophoric dysplasia. Fetal DNA obtained by amniocentesis
can be analyzed for the same deletion as that of the index case.
Complications of second trimester amniocentesis include the following:
The risk of pregnancy loss is 0.3-1%.
The risk of amniotic fluid leakage is 1-2%. In rare cases, this may lead to
oligohydramnios, arthrogryposis, and pulmonary hypoplasia.
Amnionitis occurs in 0.1%.
As the risk of Rh isoimmunization is increased 1% above the baseline risk, Rh
immunoprophylaxis is recommended for Rh-negative nonsensitized women.
Mosaicism on cytogenetic analysis is seen in 1% of samples. True fetal
mosaicism is relatively rare, and fetal blood sampling is required for confirmation.
Percutaneous umbilical blood sampling or cordocentesis
The greatest advantage of this technique is that it provides a direct fetal sample and
access to the fetus for in utero treatment.
With ultrasound guidance, a sample of fetal blood is obtained from the umbilical vessel
close to the cord insertion near the placenta. A 20- to 27-gauge needle is used, and the
approach can be transplacental in an anterior placenta or transamniotic in a posterior
Diagnostic studies that can be performed include the following:
Direct karyotyping of fetal lymphocytes can provide results within 24-72 hours.
DNA studies can be used to diagnose metabolic diseases.
Hematologic problems are especially amenable to this technique. The diagnoses
of thalassemias, sickle cell disease, hemophilia, von Willebrand disease, and
alloimmune thrombocytopenia can be made. In Rh-isoimmunized fetuses,
diagnosis and treatment of fetal anemia and thrombocytopenia is possible, as is
Immunologic tests can be performed on blood samples for diagnosis of fetal
infections (eg, specific immunoglobulin M [IgM] for toxoplasmosis, rubella,
cytomegalovirus [CMV], varicella zoster, HIV). Viral DNA can be detected using
PCR for certain infections, such as parvovirus B19.
Determine fetal PaO2, PCO2, and pH levels, as these can provide critical
indicators of fetal well-being in a small-for-date or compromised fetus. These
data can guide management decisions.
Complications associated with cordocentesis are more common in posterior placentae
and when the procedure is performed prior to 19 weeks' gestation. These include fetal
loss (1-2.3%), preterm labor (5-9%), hematoma of the umbilical cord and placental
abruption, chorioamnionitis (0.6%), fetal exsanguination from the procedure site, and Rh
isoimmunization. Rh immunoprophylaxis is mandatory in all Rh-negative nonsensitized
women after the procedure.
Late chorionic villus sampling
The technique of placental biopsy is equally effective in the second and third trimesters,
and karyotyping is possible with small amounts of placental tissue. It has the advantage
of being as accurate as amniocentesis, and it provides rapid results.
Fetal muscle and liver biopsy
Muscle biopsy is used in rare cases of Duchenne muscular dystrophy in which findings
from all previous investigations are nondiagnostic. Dystrophin levels are measured in
myoblasts by in situ hybridization. Fetal liver biopsies have also been performed to
measure enzyme levels of glucose-6-phosphatase and ornithine transcarbamylase in
patients with suspected glycogenesis and urea cycle disorders when direct DNA
techniques are not sensitive.
Diagnostic Tests in the Third Trimester and During Labor
The purpose of prenatal diagnosis in the third trimester is to confirm fetal growth, wellbeing, and lung maturity. For timely and appropriate intervention, fetal well-being needs
to be assessed in the third trimester and particularly in labor. Fetal movement is
monitored based on maternal perception. Lack of fetal movement for longer than 30
minutes suggests possible fetal compromise. Fetal lung maturity is determined as
discussed previously in case of an impending preterm delivery and in making the
decision to induce labor for any indication.
Nonstress testing is a simple low-risk procedure in which the fetal heart rate is
monitored with Doppler ultrasonography or electrodes on the maternal abdomen or a
fetal scalp electrode placed after rupture of membranes, along with the simultaneous
recording of uterine activity with a tocodynamometer. After 32 weeks' gestation, the
fetus responds to uterine contractions with tachycardia. The criteria for reactive test
results are the following:
Heart rate of 120-160 beats per minute (bpm): Fetal tachycardia may be due to
fever, drugs, or fetal arrhythmias or hypoxemia.
Normal beat-to-beat variability of more than 5 bpm: Decreased beat-to-beat
variability suggests fetal hypoxia, sleep, prematurity, maternal sedation, or
Two accelerations of more than 15 bpm lasting more than 20 seconds each
within a 15-minute test period: A reactive test is reassuring, with a high chance of
intrauterine survival over the next 7 days. A nonreactive test, which does not
meet these criteria, necessitates further testing for confirmation. The
disadvantage of the test is variable reproducibility; nonreactivity may be a late
sign of fetal hypoxia, a benign pattern, or the result of a prior asphyxial event.
Contraction stress test
The contraction stress test (CST) is used to monitor fetal heart rate in response to
uterine contractions that are spontaneous or induced with oxytocin. The contraction
should occur within 30 minutes and last 40-60 seconds with a frequency of 3 in 10
minutes. In a healthy fetus, uterine contractions cause transient hypoxia and
hypoperfusion of the intervillous space, which is relatively well tolerated. Early
decelerations start with the onset of uterine contractions, reach the nadir at the time of
peak of the contraction, and end simultaneously. These are benign and are seen in late
labor from fetal head compression.
Variable decelerations vary in their timing and relation with uterine contractions and
occur in response to cord compression. They are benign unless they are associated
with severe or prolonged bradycardia, are less than 60 bpm, last more than 60 seconds,
are associated with an overshoot acceleration lasting more than 1 minute after a
variable deceleration, or have poor beat-to-beat variability. Under conditions of
uteroplacental insufficiency, a late deceleration is induced. A late deceleration begins
10-30 seconds after the onset of uterine contraction, the nadir is later than the peak of
the contraction, and it returns to baseline after the contraction ceases.
A CST result is positive if late decelerations are present with 50% or more of
contractions. A CST finding is equivocal if decelerations are inconsistent. A negative
CST result, defined as the absence of late decelerations, is associated with a risk of
fetal demise of 0.4 cases per 1000 within the week. Drawbacks of the test are its
duration, which is approximately 90 minutes, and the need for oxytocin.
Biophysical profile test
The biophysical profile (BPP) combines the nonstress test with an assessment of
amniotic fluid volume, fetal breathing movements, fetal activity, and fetal muscle tone.
A score of 0-2 is given for each parameter. In a reactive nonstress test, each of the
following criteria earns 2 points:
At least one pocket of amniotic fluid greater than or equal to 1 cm depth
At least one episode of fetal breathing of 60 seconds duration within 30 minutes
Three or more discrete episodes of fetal movement
At least one episode of extension and flexion of extremities or spine
Scores greater than 8 indicate a low risk and the need for weekly retesting. A score of 2
is strongly suggestive of hypoxia and indicates the need for immediate delivery (if
persistent for 120 min). Intermediate scores need further evaluation. Maternal
depressant medication and cerebral or neuromuscular anomalies may result in a low
A Doppler study of fetal umbilical arterial blood flow velocity or resistance to flow is
another modality used to assess placental function, particularly to monitor high-risk
fetuses. Decreased flow velocity during diastole indicates placental insufficiency, and, in
severe cases, diastolic flow may stop completely or even reverse. Therefore, a systolicto-diastolic umbilical blood flow ratio of greater than 3 after 30 weeks' gestation is
associated with fetal compromise.
Researchers are still investigating the utility of measuring fetal arterial velocity in
assessing redistribution in the hypoxic fetus and as indicators of placental circulation in
pathologic placental processes, such as pregnancy-induced hypertension.
Fetal scalp pH is used to accurately determine fetal hypoxia and acidosis. A pH level of
less than 7.25 is considered abnormal, and a pH level of less than 7.1 mandates
immediate delivery by the quickest route.
Ultrasonography is the single most valuable modality in the identification of fetal
structural anomalies. It is also useful in the detection of abnormal growth patterns in the
fetus, in estimating gestation, and in assessing fetal well-being in the third trimester and
during labor and delivery. It is important in guiding the operator during procedures such
as amniocentesis and cordocentesis.
Ultrasonography is widely available and has no known adverse effects. Newer
techniques, including high-resolution multiplanar imaging and Doppler imaging, have
improved its yield. Disadvantages are beam attenuation with maternal adipose tissue
and poor images with an engaged fetal head or oligohydramnios.
Gestation is best estimated in the first trimester, with an error range of 3-5 days.
The range increases to 1 week at 12 weeks' gestation and 3 weeks at 36 weeks'
In the first trimester, the crown-rump length is the most accurate measure of
gestation. This is measured from the top of the head to the bottom of the torso or
the longest dimension of the fetus excluding the yolk sac and extremities.
In the second and third trimesters, parameters used to estimate gestation are the
biparietal diameter (BPD), head circumference, abdominal circumference, and
BPD is measured on the transaxial view of the head from the outer edge
of the cranium nearest the transducer to the inner edge of the cranium
farthest from the transducer. BPD, which is measured at the level of the
thalami, including the cavum septum pellucidum, should not be used in
cases of hydrocephalus, abnormal head shape, or late in the third
trimester when the head may be engaged. Measures such as a corrected
BPD have been devised to take into account differences in head shape.
Abdominal circumference is the length of the outer perimeter of the fetal
abdomen measured at the level of the stomach and intrahepatic umbilical
vein on a transverse scan. This measure should not be used in cases of
fetal growth abnormality in which the head size may be relatively
preserved or in a fetus with diaphragmatic hernia.
In comparison, femoral length is more affected by caliper placement and
technically more difficult. Femoral length may be affected by skeletal
dysplasias, Down syndrome, and fetal growth abnormalities. Only the
length of the diaphysis is measured for femur length.
A combination of these measurements yields the most accurate results.
Abnormal fetal growth patterns
Intrauterine growth retardation (IUGR): Serial ultrasonography can be used to
monitor the rate of increase in fetal biparietal diameter, abdominal circumference,
and femoral length, thus helping to identify a growth-restricted fetus.
o In the third trimester, ratios of morphometric measures such as abdominal
circumference and femoral length are used to diagnose growth
o Oligohydramnios and a poor biophysical score support the diagnosis of
growth retardation secondary to uteroplacental insufficiency.
Oligohydramnios is defined as the absence of amniotic fluid pockets or the
presence of an amniotic fluid index (AFI; sum of the vertical distance of
the largest pocket in each of 4 equal uterine quadrants) of less than 5.
o Estimated fetal weights, derived by combining several parameters (usually
head, abdominal, and femur measurements), are useful. However, they
are inaccurate at the extremes of birth weight. Symmetric growth
retardation begins earlier in gestation, affects both head and abdominal
measurements, and is caused by chromosomal or genetic anomalies or
Macrosomia: Serial ultrasonography can be used to measure the ratio of
abdominal circumference to head circumference to detect macrosomia.
Detection of Fetal Anomalies
Fetal CNS anomalies
Ultrasound is 95% sensitive in the diagnosis of hydrocephalus and
Ventriculomegaly has been defined in some studies by a measurement at the
atrium of the lateral ventricle of more than 10 mm at any time during pregnancy.
In myelomeningocele, diagnosis is made by noting a divergence of the pedicles
of the vertebrae or the presence of a fluid-filled sac. Some intracranial signs are
associated, such as ventriculomegaly, small BPD, biconcave frontal bones at 18-
24 weeks, a distorted position of the cerebellum, and obliteration of the cisterna
magna, especially if associated with Chiari II malformation.
Diagnosis of anencephaly, encephalocele, craniosynostosis, and brain
malformations, such as porencephaly, can be made based on ultrasound
findings. Fetuses with hydrocephalus or meningomyelocele should be evaluated
for chromosomal abnormalities or anatomic defects in the cardiac, renal, and
skeletal systems. Associated defects are present in 90-95% of cases.
Fetal chest abnormalities
Pulmonary hypoplasia, pleural effusions, cystic adenomatoid malformations,
sequestration, and bronchogenic cysts are all pulmonary lesions that can be
diagnosed based on ultrasound findings.
Congenital diaphragmatic hernia (CDH): Diagnosis of CDH is made based on the
presence of bowel or liver in the thorax with the accompanying blood supply,
mediastinal shift, and pulmonary hypoplasia. Polyhydramnios may be present.
After the diagnosis, serial ultrasonography should be performed to monitor fetal
growth and hydramnios and to evaluate for cardiac anomalies. Workup may
include ultrafast MRI, echocardiography, and karyotyping with amniocentesis to
exclude associated anomalies. Hydrops is a predictor of a poor outcome.
Fetal cardiac abnormalities
Detailed cardiac ultrasonography is indicated in fetuses with the following:
o Chromosomal anomalies
o Oligohydramnios or polyhydramnios
o Diaphragmatic hernia
o Defects in other systems with known cardiac associations.
Other indications for a cardiac echo antenatally include the following:
o Family history of congenital heart defect
o Maternal diabetes or systemic lupus erythematosus (SLE)
o Maternal lithium, alcohol, or progesterone intake
o Fetal arrhythmias
M-mode echocardiography is used to measure chamber size, cardiac rhythm,
pericardial effusions, and wall thickness and motion. Cross-sectional
echocardiograms show the heart position and situs and the atrioventricular (AV)
connections. Doppler echocardiograms show the direction and pattern of blood
flow, and they can depict valvular regurgitation or stenotic lesions.
Prenatally diagnosed heart disease has been associated with reduced early
neurologic morbidity in certain lesions, such as a hypoplastic left heart.
Conversely, whereas a poorer prognosis was reported earlier in prenatal cohorts
because more severe lesions are more likely to be detected, especially when
they are associated with a structural or chromosomal defect.
Fetal gastrointestinal anomalies
Gastroschisis and omphalocele are easily detected on ultrasound. Ultrasonography has
low sensitivity in the diagnosis of obstruction, which is indirectly indicated by the
presence of polyhydramnios, poorly visualized gut distal to the obstruction, and a fluidfilled portion proximal to it. An echogenic bowel, meconium peritonitis, and pseudocyst
formation are suggestive of cystic fibrosis. All of these findings indicate the need for
further cytogenetic evaluation of the fetus.
Fetal genitourinary tract anomalies
Ultrasound can detect renal agenesis, cystic disease, obstructive lesions (uteropelvic
junction obstruction and posterior urethral valves), and renal tumors. Renal dimensions,
parenchymal thinning and cysts, ratios of renal circumference to abdominal
circumference, pelvic diameters, and urinary ascites can be assessed, along with
urethral and bladder anatomy. The amniotic fluid volume provides an indication of renal
function. Oligohydramnios is associated with a poor prognosis.
Fetal skeletal anomalies
A detailed fetal ultrasound attempts to rule out skeletal dysplasias, achondroplasia,
osteogenesis imperfecta, polydactyly, and absence of a bone. Long bones are
evaluated for size, shape, symmetry, and proportions of the different segments, and the
skull is evaluated for shape and deformity. Examination of the spine and ribs helps in
the delineation of the disorder. Identification of a skeletal dysplasia and prognosis are
relatively accurate; however, in one study, a specific antenatal diagnosis was made in
60% of cases, but these were incorrect in 19% postnatally. According to some reports,
3-dimensional ultrasonography seems to provide additional visualization of skeletal
deformities and abnormal spatial relationships, such as short ribs and absent bones,
and to enable specific diagnosis.
Fetal chromosomal anomalies
In a recent meta-analysis, nuchal thickening was found to be the most accurate marker
in the second trimester. It was associated with a 17-fold increased risk of Down
Nuchal thickening in the first trimester has a sensitivity of 60-70% for the detection of
Down syndrome, with a 5% false-positive rate, whereas ultrasonography and
biochemical screening, in combination, improve the sensitivity to 80%. Other single
subtle markers (eg, choroid plexus cysts, shortened long bones, echogenic bowel) are
MRI is an important adjunct to ultrasonography. It is used mainly in the assessment of
cases with equivocal ultrasonographic findings or when prenatal ultrasound is not
reliable in the identification of fetal anomalies, such as in the setting of maternal obesity
or oligohydramnios. The advantage of the newer fast and ultrafast sequence MRI is that
they have minimized motion artifacts; thus, sedation is not needed. A variety of
sequences have been used, including echoplanar, half-Fourier single-shot turbo spinecho (HASTE), and fast spin-echo sequences. Of these, HASTE has proven to be an
excellent method of fetal imaging. A recent meta-analysis showed that ultrafast MRI in
the third trimester provided additional information compared to ultrasound in fetal
diagnosis in 23-100% of cases, particularly those involving the posterior fossa of the
Advantages of MRI include the following:
Absence of ionizing radiation
Large field of view
Superior soft tissue contrast enhancement
Good image quality in oligohydramnios
More precise volumetric measurement
Better intracranial delineation
Limitations of MRI include the following:
Spatial resolution inferior to that of ultrasonography
Poor depiction prior to 20 weeks' gestation
Safety question - not approved by the Food and Drug Administration (FDA), but
no known significant risk beyond the first trimester
MRI may be used if other nonionizing imaging modalities are inadequate or if ionizing
radiation would otherwise be required for further evaluation.
Indications for MRI evaluation include the following:
Fetal cerebral anomalies: MRI has been most successful in the identification of
posterior fossa abnormalities, migrational anomalies (eg, lissencephaly,
polymicrogyrias, schizencephaly) at 30-32 weeks' gestation, agenesis of the
corpus callosum, white matter disease, hydrocephalus, and ischemic or
Volumetric analysis: The size of the fetus or individual organs, such as the liver,
can be determined. In CDH, volumetric measurements of the right fetal lung and
the position of the left hepatic lobe appear to be good prognostic indicators and
help in planning therapeutic interventions.
Congenital high airway obstruction syndrome: MRI can be used to confirm upper
airway obstruction by demonstrating hyperinflation of both lungs and dilated fluidfilled airways below the level of obstruction. Fetal neck masses such as cystic
hygromas and teratomas can be identified, allowing early intervention when
Congenital hemochromatosis: T2-weighted MRI can be used to confirm the
Amniotic band syndrome: MRI provides an accurate diagnosis.
CT scanning has limited applications in prenatal diagnosis. It is used mainly when MRI
is contraindicated in the mother (eg, if she has a pacemaker, an intraocular metallic
foreign body, or intracranial ferromagnetic surgical clips).
The advantage of CT scanning is that it better delineates fetal bony anatomy than other
The limitations of CT scanning include possible teratogenesis due to ionizing radiation if
it is performed in the first trimester and a risk of cancer induction. In children, a risk of
mortality from cancer of 1 per 220-440 cases has been reported.
Indications for CT scanning include pelvimetry and CT amniography to confirm
monoamnionicity if ultrasonography provides inconclusive data.
A prolonged QT interval or Wolff-Parkinson-White syndrome can be detected in the
prenatal period on fetal magnetocardiograms through evaluating T waves and obtaining
current arrow maps. A weak, prolonged T wave is likely a good indicator of the
FETAL THERAPY: SURGERY
As new intrauterine surgical techniques have been developed, anesthesia for the
procedures has also evolved. The major objectives are to ensure maternal and fetal
safety. Specific goals are the prevention of maternal hypoxia and hypotension, together
with the maintenance of optimal uterine blood flow. Lower doses of epidural and spinal
anesthetic agents are needed in pregnant women because of increased epidural
pressure and a lower volume of cerebrospinal fluid in the vertebral space.
To promote fetal safety, procedures are generally performed in the second
trimester, if possible, to avoid potential teratogenicity from the anesthetic agents.
Fetal asphyxia: Normal maternal PaO2 should be maintained, and blood pressure
should be maintained (with intravenous fluids and, if necessary, ephedrine, a
vasopressor with central adrenergic stimulant action).
Tocolysis: Uterine contractions are stimulated with the uterine incision and need
to be stopped before preterm labor sets in. The agents used for this purpose
include indomethacin, magnesium sulphate, and terbutaline.
Indomethacin is administered preoperatively and continued postoperatively for 35 days. Fetal adverse effects include premature closure of the ductus arteriosus.
Anesthetic agents commonly used are isoflurane inhalation with 100% oxygen
along with muscle relaxants. For surgeries involving direct fetal manipulation,
direct intramuscular fentanyl and pancuronium (a muscle relaxant and vagolytic)
administered to the fetus have been tried prior to hysterotomy under ultrasound
Monitoring During Surgery
The parameters monitored during and after surgery include the following:
Myometrial contractions and intrauterine pressures
Maternal blood pressure, ECG, and pulse oximetric and blood gas levels
Fetal pulse oximetric measurement (50-60% saturation), heart rate, blood gases,
Ultrasonographic findings in cases of fetoscopic surgery
Fetal temperature (Maintain temperature with continuous warm sodium chloride
irrigation, minimized exposure, and increased ambient temperature.)
Three approaches are currently used for invasive fetal therapy.
1. Ultrasonography-guided vesicoamniotic and, less commonly, thoracoamniotic
shunt placement, is used in a fetus from 16 weeks' gestation to when lung
maturity makes postnatal treatment the best option. Complications are
inadequate function, migration, and iatrogenic gastroschisis.
2. Fetoscopic techniques now have a clinical application in the ligation of umbilical
cords in acardiac twins, in selective laser photocoagulation of communicating
vessels in twin-to-twin transfusions, and in the ablation of posterior urethral
o The procedure is performed inside the uterus using endoscopes, with a
much smaller hysterotomy than that needed for open procedures. This
lessens the risks of preterm labor and fetal hypothermia and improves
fetal hemostasis during the procedure.
o The success of the procedure depends on the use of both a
transabdominal ultrasound intraoperative view and a simultaneous
endoscopic view to guide placement of the trocars and cannulae.
o The drawbacks of fetoscopic surgery are the risk of bleeding (avoiding the
transplacental route decreases this risk), rupture of membranes, and
chorioamnionitis. Fetoscopy may also be difficult because of poor access
to the fetus due to fetal position or polyhydramnios.
3. Open fetal surgery is currently performed at select centers in instances in which
the risk of the procedure to the mother and fetus is overridden by a diagnosis
with a known poor outcome. Complications such as chorioamnionitis, preterm
labor, bleeding, and direct trauma to the fetus are risks in most of these
These surgical techniques are considered appropriate for 9 lesions.
1. Obstructive uropathy
Patients with severe obstructive uropathy with bilateral hydronephrosis and
oligohydramnios revealed with ultrasonography should be evaluated for possible
Prior to intervention, a cordocentesis is performed to document a normal
karyotype and to exclude other major fetal anomalies.
This is followed by serial fetal bladder aspirations of urine under
ultrasonographic guidance, which can help in the diagnosis of progressive
renal damage (tonicity and electrolyte levels in the urine) and can relieve
pressure if performed prior to 20 weeks' gestation.
A vesicoamniotic shunt is indicated in persistent megacystis with adequate
ultrasonographic and biochemical renal function to reduce pressure in the
urinary tract and to improve pulmonary development and decrease uterine
Fetoscopic techniques can be used for fulguration of posterior urethral
valves, placement of vesicoamniotic shunts, and vesicostomy. If all of
these procedures fail, open vesicostomy with marsupialization of the
bladder wall to the abdomen may be attempted.
Open surgery has a high fetal mortality rate (45%). In a study evaluating
long-term postnatal outcomes after fetal surgery for posterior urethral
valves in 14 patients, 8 patients lived to a follow-up period of 11.6 years.
Chronic renal failure was present in 5 of them. This study emphasized that
fetal intervention may assist in prolonging gestation to term, but the
sequelae of the lesion on renal function may not be preventable. Fetuses
with urethral atresia, despite vesicoamniotic shunts, have a poor
prognosis, probably due to the severity and timing of the lesion.
Ventriculoamniotic shunts used for the decompression of obstructive
hydrocephalus have had poor results and have caused procedure-related
complications. Thus, their use is not indicated.
Fetal surgical procedures, both open and endoscopic, have been
performed to repair myelomeningocele in utero. The open procedure is
performed at 24-30 weeks' gestation and is shown to reduce both
hindbrain herniation and the number of patients requiring shunts for
o An endoscopic procedure has been performed by the Vanderbilt group,
which consists of maternal laparotomy, followed by placement of a splitthickness maternal skin graft over the exposed spinal cord and neural
elements of the fetus. The skin graft is attached with fibrin glue prepared
from autologous maternal cryoprecipitate. The procedure has been
performed at 22-24 weeks' gestation, with the rationale that neurologic
injury is partly acquired through exposure of neural elements to amniotic
fluid and the uterine wall.
3. Pleural effusion
The use of thoracoamniotic shunts is indicated in a fetus with pleural effusion that
reaccumulates after thoracocentesis and causes mediastinal shift. The aim of the
shunt is to decompress the chest, promote pulmonary development, and treat the
4. Twin-to-twin transfusion syndrome
Umbilical cord ligation may be indicated in some cases of twin-to-twin transfusion
syndrome. In acardiac twins, twin reverse arterial perfusion (TRAP) is
characterized by artery-to-artery and vein-to-vein communications between twins
in a monozygotic placenta. The donor twin is at risk for congestive failure, and
the recipient is acardiac and inadequately perfused. Umbilical cord ligation is
indicated in the acardiac twin or a nonviable twin involved in twin-to-twin
transfusion after 21 weeks' gestation. Selective laser photocoagulation of the
cord circulation, using YAG laser, can be performed prior to 21 weeks. In this
procedure, an endoscope is introduced intra-amniotically through a port with
5. Amniotic band syndrome
In amniotic band syndrome, recent attempts have been made to lyse amniotic
bands using fetoscopic techniques when a high risk of limb amputation is
6. Congenital diaphragmatic hernia
Many investigators believe that intrauterine therapy is indicated in fetuses with
CDH who have a poor prognosis.
These patients have been defined as those with the liver in the chest and
those with a low lung-to-head ratio (<1.0) on ultrasound.
o Additional criteria for intervention include a singleton fetus, normal
karyotype, diagnosis made prior to 25 weeks' gestation, and absence of
o The procedures that have been attempted since the early 1990s involved
definitive repair by reduction of viscera from the chest, patch placement
over the diaphragm, and abdominal silo construction to reduce intraabdominal pressure. These carried a high mortality rate in patients with a
poor prognosis and have since been abandoned.
o The current fetal surgery for CDH is tracheal occlusion.
This causes enlargement and real growth of the lungs, often
pushing the abdominal viscera back into the abdomen. The trachea
is occluded by external metal clips placed either fetoscopically or in
an open fashion, delivering the head and neck through a
Both fetoscopic and open methods have had comparable
outcomes. Survival rates in these high-risk patients have been
approximately 33%, compared to 10% with conventional postnatal
therapy. Significant morbidity related to prematurity, atrial
perforation, pulmonary insufficiency, and neurologic complications
have been observed.
An ex utero intrapartum (EXIT) procedure to remove the clips,
aspirate lung fluid, administer surfactant, and intubate the trachea
is then performed while the fetus is still on placental support,
followed by delivery of the baby. The EXIT procedure is performed
at 36 weeks' gestation or earlier if fetal hydrops or impending
preterm labor is present.
Recent small trials of internal tracheal occlusion by a detachable
balloon placed through a single uterine port using fetal
bronchoscopy and ultrasound have yielded good results. The
advantage of the technique is that it is technically less demanding
and has a lower risk of recurrent laryngeal nerve and tracheal
7. Congenital high airway obstruction syndrome
When congenital high airway obstruction syndrome (CHAOS) is complicated by
hydrops, an EXIT procedure to place a tracheostomy may be of use. Earlier,
fetoscopic, intervention may also be reasonable. The usual causes are laryngeal
or tracheal stenosis.
8. Sacrococcygeal teratoma
Fetuses with sacrococcygeal teratoma may develop hydrops from high output
failure. Early attempts at open resection of the teratoma or radiofrequency
ablation of the tumor proved to have a high rate of fetal mortality and maternal
Coagulation or ligation of the feeding vessels at the base of the tumor
directly at fetoscopy by laser is now possible at an early gestation. This
treatment slows the vascular steal and reverses the high-output failure.
o Targeted radiofrequency ablation of the feeding vessels via a
percutaneous probe under ultrasonic guidance is also effective. The
potential risks include gas emboli, hyperkalemia, thrombosis, hemorrhage,
hemolysis, burn injury to the adjacent tissue, and premature rupture of
o Fetal hemodynamic status requires monitoring during and immediately
following the ligation because of an increase in afterload after ligation of
the previously low-resistance tumor circuit.
9. Congenital cystic adenomatoid malformations
Of fetuses with congenital cystic adenomatoid malformations, 10% develop
hydrops, and these have a mortality rate approaching 100%. They can be treated
at open fetal surgery with resection of the cystic lobe prior to 32 weeks' gestation.
In some instances, this improves lung growth and allows the hydrops to resolve.
The macrocystic form of cystic adenomatoid malformation may be drained with
pleuroamniotic shunts, thus ameliorating the space-occupying effects and
improving lung growth.