Board Review Quiz answers October

Question 21Answer: ultrasonography of the adrenals

Screening programs for congenital a...

Elevated adrenocorticotropic hormone (ACTH) values might be seen in Cushing disease, but the girl in the
of malignancy in most cases, leading to definitive surgery and other necessary therapy. The most common
thyroid malignanci...
suggest potential surgical emergencies such as appendicitis (tenderness localized to the right lower quadrant with
or with...
Annual alpha-fetoprotein screening in children who have the FAP gene is recommended by some experts to
screen for hepatobl...
Anorectal atresia is associated with delayed or absent passage of stool. Abdominal distention classically develops
over th...
Intestinal small bowel biopsy of the duodenum or jejunum remains one of the most useful tests in the evaluation
of a child...
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Board Review Quiz answers October

  1. 1. Board Review Quiz answers October Question 21Answer: ultrasonography of the adrenals Screening programs for congenital adrenal hyperplasia (CAH) were developed to identify male infants who have 21-hydroxylase deficiency and look ostensibly normal at birth, but who could develop salt loss with hyperkalemia, dehydration, vomiting, and shock within the first 2 postnatal weeks. Girls who have this condition usually are diagnosed at birth because of ambiguous genitalia. The boy described in the vignette looks well, but he is only 6 days of age, and 10 days to 2 weeks may be required for symptoms to manifest. CAH occurs in 1:12,000 to 1:16,000 newborns. Approximately 75% of affected infants have the more severe salt-losing form of the disorder. The most important action in a child in whom CAH is strongly suspected is to confirm the diagnosis and begin treatment before the onset of a severe salt-losing crisis. Salt loss is subtle but usually causes symptoms by 7 to 11 days after birth. Therefore, the first action is to measure serum sodium and potassium concentrations. If the potassium concentration is even slightly elevated or the sodium concentration slightly low, glucocorticoid, salt, and mineralocorticoid replacement should be started immediately. An elevated repeat 17-hydroxyprogesterone result obtained through the regional neonatal screening laboratory can provide rapid confirmation that this is the correct decision and, therefore, should be ordered for the infant in the vignette. Just before or immediately after initiation of treatment, confirmatory laboratory studies should be sent to a reference laboratory, but results take a long time to return. The at-risk child could develop life-threatening salt loss and adrenal insufficiency during the waiting period. If initial electrolyte screening results are normal, babies still should be followed closely until results of studies of steroid precursors have returned because decompensation from salt loss sometimes can occur later in the first postnatal month. Measures of serum cortisol and aldosterone do not aid in diagnosing 21-hydroxylase deficiency. Random cortisol levels in unaffected babies can be low, and aldosterone levels may not be diagnostic for CAH. Measurement of adrenal precursors (eg, 17-hydroxyprogesterone) before the enzymatic block is a preferred diagnostic technique. Although urine potassium levels can be low and urine sodium levels can be high in babies who have CAH and salt loss, serum measures are better indicators of the impending salt-losing crisis. Urine 17-ketosteroids crudely measure some androgenic steroids, but this laboratory study requires a 24-hour sample for accurate assessment and rarely is used. All male infants have elevated concentrations of testosterone because of hypothalamic pituitary testicular activation in the neonatal period. Therefore, an elevated testosterone value does not aid in the diagnosis of CAH. Female infants who have CAH may have a fully formed phallic structure (Item C21A), but they lack testes. Adrenal glands in neonates can be identified by ultrasonography, but adrenal size often reflects the stress of delivery and cannot be used to help in the diagnosis of CAH. Question 36 Answer: hydrocortisone hemisuccinate intravenously Adrenal insufficiency manifests as nausea, vomiting, and circulatory collapse, as reported for the girl in the vignette. Treatment requires administration of glucocorticoid and mineralocorticoid. Because individuals who have adrenal insufficiency lose sodium and retain potassium, initial rehydration should be with 0.9% NaCl without potassium. The addition of glucose to the rehydration fluid, as reported in the vignette, protects against hypoglycemia, which also may be a manifestation of glucocorticoid deficiency. Hydrocortisone hemisuccinate administered intravenously, or by other parenteral routes, can resuscitate a glucocorticoid-deficient child rapidly. In contrast, cortisone acetate is poorly soluble, and when administered intramuscularly, enters the blood stream so slowly that it will not resuscitate a child who has adrenal insufficiency. If hydrocortisone or other glucocorticoid is supplied in a readily available form, no pressor (eg, dopamine) is required. There no longer is a commercially available parenteral mineralocorticoid. Aldosterone has a very short half-life and is not available as a commercial preparation. However, because high-dose hydrocortisone has mineralocorticoid effect, infusion of 0.9% NaCl with high-dose hydrocortisone can replace mineralocorticoid, salt, and glucocorticoid. Question 42 Answer: Prolactin The 16-year-old girl described in the vignette has had arrest of pubertal development with failure of menarche for at least 2 years. The bitemporal visual field deficits imply the presence of a large suprasellar mass. The two most common causes for such a mass lesion are pituitary macroadenomas and craniopharyngiomas, and the most common macroadenoma is a prolactinoma. Elevations of prolactin values could be due to increased prolactin secretion from a prolactinoma or to compression of the pituitary stalk by another pituitary tumor, a craniopharyngioma, or other space-occupying lesion. Because stalk compression interferes with the dopaminergic inhibitory influences on pituitary release of prolactin, prolactin concentrations of up to 200 mcg/L may be due solely to stalk compression. Prolactin concentrations in that range interfere with normal menstrual cycling and suppress normal puberty. A large tumor also might interfere with pubertal and other pituitary hormones because of its mass. Accordingly, measuring prolactin will be most helpful in determining whether the girl has a prolactinoma. Prolactinomas usually respond to treatment with medication such as cabergoline; surgery rarely is
  2. 2. required. Elevated adrenocorticotropic hormone (ACTH) values might be seen in Cushing disease, but the girl in the vignette exhibits no signs or symptoms of Cushing disease, such as weight gain, skin striae, hypertension, cushingoid facies, and muscle weakness. Further, the pituitary tumors in affected individuals rarely are macroadenomas because the symptoms lead to an earlier diagnosis. A low concentration of insulin-like growth factor-1 might suggest growth hormone deficiency, and a high concentration suggests acromegaly. No signs or symptoms of acromegaly, such as rapid growth, coarsening of facial features, sweating, or thickening of skin, are described for the girl. Measurement of thyroid-stimulating hormone (TSH) might identify a TSH-producing tumor or severe hypothyroidism that is primary because of thyroid gland failure. A TSH-producing tumor, which is very rare, produces hyperthyroidism, and no symptoms of hyperthyroidism are described for the girl in the vignette. Sometimes severe primary hypothyroidism can lead to the development of an enlarged pituitary composed of thyrotropes (TSH-secreting cells), but no symptoms or signs of severe hypothyroidism (eg, pallor, lethargy, dry skin, coarse facies, slow heart rate, myxedema) are described. Measurement of luteinizing hormone would be useful if the clinician suspected ovarian failure. However, follicle-stimulating hormone is a better measure of ovarian failure because it rises higher than luteinizing hormone if there is ovarian dysfunction. Rare pituitary tumors produce luteinizing hormone, but these tumors do not produce neuroendocrine symptoms in females unless they also produce follicle-stimulating hormone. Question 58 Answer XY The boy described in the vignette, who has normal descended testes and a normal penis and is discovered to have fallopian tubes and a rudimentary uterus, has the persistent müllerian duct syndrome. A peptide hormone (müllerian inhibiting substance [MIS] or anti-müllerian hormone [AMH]) produced by the testis induces regression of the müllerian ducts during fetal development. These ducts become the fallopian tubes and uterus as well as the upper part of the vagina if there is no regression. Genetic defects that lead to failure of production of MIS or lack of receptors for this hormone are responsible for failure of regression of müllerian tissues in otherwise normal males. This is an autosomal recessive disorder and is associated with an XY chromosomal pattern. The SRY gene is the male-determining gene on the Y chromosome. Children who have an XX chromosome pattern rarely present with sex reversal (male phenotype) because of a translocation of the SRY gene to an X chromosome or an autosome. Affected children have gonads that generally are composed of testicular tissue and should not have müllerian remnants. Children who have an XX/XY chromosomal pattern usually have external genitalia that reflect true intersex, and gonads contain a variable mix of testicular or ovarian tissue that may differ in each gonad. Unilateral müllerian remnants may be present if mostly ovarian tissue is found on that side. Individuals who have the XXY complement have Klinefelter syndrome. They have normal male external and internal sexual development at birth, although testes and phallus may be somewhat small. As they grow, they express components of Klinefelter syndrome of variable severity, ranging from late-onset infertility to severe behavioral and neurodevelopmental problems. Children who have an XO/XY chromosomal pattern usually have normal male differentiation but may have somewhat small phalluses. They may have infertility and short stature. Some affected children have "mixed gonadal dysgenesis" that results in ambiguous genitalia and some manifestations of Turner syndrome. The presence of Y chromosomal material in a dysgenetic gonad increases the risk for malignancy within the gonad, although the risk is lower than previously believed. Question 74maternal aunts are infertile The baby described in the vignette, who has mild masculinization and palpable gonadal masses with an XY karyotype, is an undervirilized XY infant (male pseudohermaphroditism). Because gonads are present below the inguinal ligament, there is testicular tissue. Even with careful evaluation, an underlying cause cannot presently be determined in up to 40% of undervirilized XY infants. However, one of the most common findings is androgen insensitivity (AIS), which may be complete (CAIS) or partial (PAIS). The finding usually represents a defect in the androgen receptor and is inherited in an X-linked pattern. Therefore, some maternal aunts are likely to have the same disorder, have an XY chromosomal pattern, and be infertile. Because this disorder is not inherited through the father, a history of infertility in paternal relatives would not be expected. Failure of masculinization of an XY fetus cannot be attributed to maternal androgen or progesterone treatment or to paternal exposure to pesticides, even if they have antiandrogenic effects. Physicians faced with the diagnostic management and care of XY infants should consult with experienced endocrinologists, geneticists, and psychological support personnel. Additional diagnostic studies should rule out other genetic disorders, such as 5 alpha-reductase deficiency and 17-ketosteroid reductase defects. The difficult decision of determining the sex of rearing of the affected child must involve the parents. A trial of exogenous testosterone can help to define the likely adult response to androgen and assist in this decision. Question 90fine-needle aspiration thyroid biopsy All children who have discrete thyroid masses should be referred to an endocrinologist. The previous chemotherapy and irradiation to the chest probably received by the girl in the vignette for treatment of leukemia places her at risk for a thyroid malignancy. Thyroid cancer accounts for about 10% of the second malignancies among cancer survivors and is especially common among survivors of Hodgkin lymphoma. A thyroid mass associated with lymphadenopathy that is firm, hard, and fixed is much more likely to be malignant than a soft, mobile mass without associated adenopathy. A fine-needle aspiration biopsy can provide pathologic confirmation
  3. 3. of malignancy in most cases, leading to definitive surgery and other necessary therapy. The most common thyroid malignancies in children are papillary and follicular carcinomas. Serum calcitonin concentration should be measured if there is suspicion of medullary carcinoma of the thyroid, but this malignancy is not found frequently after irradiation. A thyroid scan (Item C90A), whether technetium or 131-iodine, probably can help to identify the nodule, but the differentiation between "hot" and "cold" nodules, once so important in diagnosis, no longer is made. Thyroid malignancies may be found in lesions that take up iodine or technetium. Thyroid ultrasonography may be very useful for choosing the area to biopsy and assessthe extent of the thyroid lesion. Some suggest that biopsy performed with ultrasonography is more likely to be informative, but in this case, the pathologic reading of the aspiration biopsy of the large mass should be definitive. Question 106Pseudohypoparathyroidism Pseudohypoparathyroidism is an autosomal dominant disorder usually associated with mutations in the stimulatory G protein alpha - subunit. As a result, the body does not respond to parathyroid hormone and other hormone effects mediated through this G protein mechanism. Individuals who have this disorder tend to be short and stocky, with short fourth metacarpals and metatarsals (brachydactyly) (Item C106A) and relatively slow mentation or mild mental retardation. Because the disorder is imprinted, children born to women who have this disorder have the full clinical expression with hypocalcemia and hyperphosphatemia, but children born to men who have the the disorder have the phenotype without the signs and symptoms of hormone resistance (sometimes termed pseudopseudohypoparathyroidism). Genomic imprinting is the mechanism for sex-linked transmission of some specific genetic information. It is the result of zygotic alterations in the methylation pattern of genes that leads to inactivation of some genes derived from the maternal or paternal lines. Examples of other imprinted disorders include Beckwith-Wiedemann syndrome, Prader-Willi syndrome, and Angelman syndrome. Although hypocalcemia and subcutaneous ossifications are the most common manifestations of pseudohypoparathyroidism, resistance to thyroid-stimulating hormone (TSH), gonadotropins, and vasopressin also is common. This leads to elevated TSH concentrations in a newborn as a marker of hypothyroidism. McCune Albright syndrome is a disorder associated with polyostotic fibrous dysplasia, irregular café au lait skin macules, and sexual precocity. Other endocrine and somatic abnormalities, including hyperthyroidism, Cushing syndrome, and gigantism (growth hormone excess), have been reported. Multiple endocrine autoimmune disorders do not present with the same physical appearance as reported for the mother in the vignette, although hypothyroidism and hypoparathyroidism may be prominent endocrine deficiency disorders as a result of autoimmune destruction of these glands. Noonan syndrome usually is inherited as an autosomal dominant disorder and is associated with short stature, delayed puberty, classic facial appearance (Item C106B), and mild mental retardation in many cases. The disorder is not associated with hypocalcemia or hypothyroidism. Vitamin D-resistant rickets is not associated with hypothyroidism and the physical findings reported for this family. Question 48 send the patient home with instructions for supportive care The patient described in the vignette has signs and symptoms consistent with viral gastroenteritis. This is a clinical diagnosis that requires no further evaluation in the absence of toxicity, rebound tenderness, distention, or evidence for dehydration, as in this child. Neither a complete blood count nor serum electrolyte determinations are likely to alter management. The boy should be sent home with instructions for supportive care. Most children who have vomiting due to gastroenteritis can maintain sufficient levels of hydration with glucose- and electrolyte-containing solutions. Intravenous hydration is not required unless fluid loss exceeds 10% of body weight or the patient is experiencing more moderate 5% to 10% dehydration in conjunction with persistent vomiting and an inability or unwillingness to take oral fluids. Abdominal radiographs provide limited information for the evaluation of a child who has vomiting and diarrhea, and even in suspected appendicitis, rarely are helpful. Further evaluation for abdominal pain is indicated if information gained from the history and physical examination
  4. 4. suggest potential surgical emergencies such as appendicitis (tenderness localized to the right lower quadrant with or without rebound), small bowel obstruction (absent bowel sounds, abdominal distention), perforated viscus (rigid abdomen, distention, fever, toxicity), malrotation (diffuse tenderness, abdominal distention), intussusception (severe crampy abdominal pain alternating regularly with periods of pain relief), or peritonitis (fever, toxicity, diffuse abdominal tenderness). Question 82 repeat the bilirubin measurement in 2 weeks Hepatobiliary obstruction is characterized by elevation of three laboratory parameters: conjugated (direct) bilirubin, alkaline phosphatase, and gamma-glutamyl transpeptidase. None of these markers is completely specific for hepatobiliary obstruction. For example, direct bilirubin can be elevated by intrahepatic cholestasis (as seen in Alagille syndrome and chlorpromazine toxicity), alkaline phosphatase can be raised by bone disease, and gamma-glutamyl transpeptidase can be increased by anticonvulsants and alcohol consumption. Therefore, if biliary obstruction is suspected, hepatobiliary ultrasonography should be performed to evaluate for bile duct dilation, gallstones, and hepatobiliary sludge. Gallstones composed primarily of calcium bilirubinate are referred to as pigment stones; those composed primarily of cholesterol are termed cholesterol stones. "Biliary sludge" is an amorphous material composed of cholesterol, mucin, and bilirubinate that is thicker than regular bile but not as hard as a stone. Sludge in the common bile duct can contribute to both obstructive jaundice and pancreatitis. The patient described in the vignette had a recent gallstone removed endoscopically. Generally, such patients can be followed clinically, and repeat laboratory studies are not necessary if the patient is asymptomatic. This girl's bilirubin concentration is mildly elevated, which is not uncommon after a recent episode of obstructive jaundice; repeat measurement in 2 weeks can determine whether the hyperbilirubinemia has resolved. Repeat endoscopic retrograde cholangiopancreatography is not necessary at this time, although it should be considered if there is evidence of another retained stone. Transaminase values are normal, making both autoimmune and viral hepatitis unlikely. For a patient who has jaundice due to persistent biliary sludge, oral administration of the synthetic bile acid ursodeoxycholic acid may help facilitate biliary flow and promote sludge dissolution. Cholic acid generally is not used in the chemical dissolution of biliary sludge and gallstones. Question 34early introduction of hypocaloric (trophic) enteral feeding Parenteral nutrition is a lifesaving therapy in the neonate or infant who requires a prolonged period of fasting. Total parenteral nutrition (TPN) involves the administration of intravenous dextrose, free amino acids, lipids, and electrolytes into a central vein (typically the subclavian). Trace elements, including zinc, iron, and selenium, must be added if prolonged fasting is expected. For infants, prolonged TPN is used primarily in those who are critically ill and have bowel dysfunction due to gastrointestinal malformations (gastroschisis, omphalocele) or necrotizing enterocolitis. The four primary complications of this treatment are infection, thrombosis, electrolyte abnormalities, and cholestasis. Risk factors for cholestasis include severe necrotizing enterocolitis, prolonged bowel rest, bacterial overgrowth, and recurrent catheter-related sepsis. Early enteral feeding, even in small volumes, is believed to treat PN cholestasis by stimulating bile flow and promoting intestinal motility. Although no randomized trials have proven definitely the concept that trophic feedings reduce cholestasis, animal studies suggest that they improve intestinal mucosal integrity and pancreaticobiliary function. Therefore, trophic feedings are recommended if patients can tolerate them. Additional interventions that may reduce PN cholestasis include: not giving excessive glucose, using ursodeoxycholic acid to increase bile flow, and treating bacterial overgrowth. Another strategy is to provide the patient's daily PN in a condensed time period ("cycling" the PN). A recent small case series also suggested that using an omega-3- based lipid emulsion (instead of the more commonly used omega-6-based emulsion) can treat cholestasis successfully. Reduction of dextrose, removal of branched-chain amino acids, addition of vitamin E, and elimination of the long-chain fat preparation have not been shown to be effective treatments for cholestasis. Question 50 genetic testing to determine his risk The boy described in the vignette, whose father has familial adenomatous polyposis (FAP), has a 50% chance of inheriting this syndrome. This autosomal dominant condition is characterized by a mutation in the APC gene found on chromosome 5. Patients who have the mutation commonly develop colonic adenomas (small tumors ranging from 1 to 5 mm in size) (Item C50A) in their teenage years and have a 100% lifetime risk of developing colorectal neoplasia if the colon is not resected. Adenomas rarely develop before age 10; the mean age of adenoma development is 16 years. Other tumors associated with FAP include duodenal carcinoma, soft-tissue sarcoma, and mandibular osteomas. When FAP is associated with soft-tissue tumors such as desmoids and osteomas, it is referred to as Gardner syndrome. Approximately 1% of patients who have APC mutations present with hepatoblastoma in the first year after birth. Other inherited polyposis syndromes include juvenile polyposis coli, Peutz-Jegher syndrome (Item C50B), and Bannayan-Riley Ruvalcaba syndrome (Item C50C). The availability of reliable and reproducible genetic screening has simplified the management of children born to parents who have FAP gene mutations. In this case, the father's and son's blood can be analyzed for mutations in the APC gene. If the son carries an FAP gene mutation, he should undergo colonoscopy annually beginning at age 10 years. If adenomas are identified, colectomy must be undertaken to prevent the development of cancer, although the exact timing of this procedure remains a topic of debate. In contrast, if results of genetic testing are negative, the patient can have colonoscopy postponed until 25 years of age.
  5. 5. Annual alpha-fetoprotein screening in children who have the FAP gene is recommended by some experts to screen for hepatoblastoma. However, this is not necessary if the patient does not carry the FAP gene. Similarly, ultrasonography, colonoscopy, and fecal occult blood testing are unnecessary at this time if the patient is not a gene carrier. The indication for genetic testing is clear in this vignette because the father had colectomy findings consistent with FAP. However, many children who have polyposis syndromes present with rectal bleeding, but do not have a clear family history. The approach to evaluating a child in whom polyposis syndrome is suspected includes combining genotyping (as determined by genetic analysis) with phenotyping (as determined by upper endoscopy, colonoscopy, radiography, and video capsule endoscopy). Question 83 malrotation of the bowel The patient described in the vignette presents with bilious emesis in the first postnatal week. Bilious emesis always is a surgical emergency in the newborn. The differential diagnosis includes any form of anatomic or functional gastrointestinal obstruction, such as an ileus, that may be associated with sepsis. This infant is not systemically ill, febrile, dehydrated, or hemodynamically unstable. Although her abdomen is not distended, the absence of bowel sounds on auscultation and the paucity of bowel gas on abdominal radiograph (Item C83A) are concerning for malrotation of the bowel with a midgut volvulus. Early in this condition, findings on the physical examination may be as described, but they can change rapidly, depending on how much the mesenteric perfusion has been compromised. Later signs include rectal bleeding, hematemesis, palpable bowel loops, and an uncomfortably distended abdomen with respiratory embarrassment and hypovolemic shock. If not diagnosed and expeditiously addressed surgically, most of the small intestine may be lost. Surgical exploration may need to precede any contrast gastrointestinal imaging (upper gastrointestinal radiographic series (Item C83B) if the patient is unstable. Plain radiographs may demonstrate a normal, nonspecific bowel gas pattern; duodenal obstruction with the appearance of a "double bubble" (Item C83C); gastric distention with a paucity of distal intraluminal gas; or a generalized pattern of dilated small bowel loops. Half of all cases of midgut volvulus occurring in the first postnatal year appear in the first week, another 25% appear in weeks 1 through 4, and the final 25% appear from 1 month to 1 year of age. These account for 90% of all cases of acute volvulus in pediatric patients.
  6. 6. Anorectal atresia is associated with delayed or absent passage of stool. Abdominal distention classically develops over the first 48 hours of postnatal life regardless of whether the infant is fed. This condition and tracheoesophageal fistula (TEF) may be part of a broader spectrum of associated malformations known as the VATER or VACTERL association (V=vertebral anomalies, A=anorectal atresia, C=cardiac malformations, TE=TEF, R=renal anomalies, L=limb anomalies). TEF typically presents with respiratory distress or poor handling of oropharyngeal secretions and may present with gastrointestinal obstruction in utero or postnatally. The clinician should evaluate the patient who has anorectal atresia or TEF carefully for other findings in the VACTERL spectrum. Cystic fibrosis may be associated with meconium ileus and delayed passage of stool beyond 24 hours. Affected infants may have bilious emesis if fed, and plain abdominal radiography demonstrates dilated loops of bowel of varying caliber. If associated with meconium peritonitis or a pseudocyst, intraperitoneal calcification may be seen. A septic ileus is associated with systemic illness, abdominal distention, and a paucity of bowel gas or dilated loops of bowel on radiographs. Question 146upper gastrointestinal endoscopy Upper gastrointestinal bleeding (bleeding proximal to the ligament of Treitz) may be either acute (presenting with melena and hemodynamic instability) or chronic (presenting with anemia). Common causes include gastric or duodenal ulcers, chronic gastritis, esophageal or gastric varices, and reflux esophagitis. Vascular lesions such as arteriovenous malformations or telangiectasias (as seen in hereditary hemorrhagic telangiectasia [Osler-Weber- Rendu disease]) also can present with chronic gastrointestinal blood loss. Dieulafoy lesion is another cause of upper gastrointestinal hemorrhage that presents with massive and recurrent bleeding and is caused by an abnormally enlarged arteriole in the gastric cardia or duodenum that periodically bleeds into the gastric lumen. Upper gastrointestinal endoscopy remains the initial diagnostic test of choice for most upper gastrointestinal hemorrhages because it is not only highly sensitive for mucosal lesions such as peptic ulcers and varices, but also allows the endoscopist to treat any bleeding lesions. Bleeding varices usually are treated by placing rubber bands around varices (variceal ablation by banding) or by injecting sclerosant into the varices (sclerotherapy). In contrast, bleeding gastric and duodenal ulcers typically are treated by electrocautery of the ulcer or by local injection of epinephrine. Video capsule endoscopy is a new technique in which a patient swallows a small "pill" containing a digital camera and transmitter. The camera can take thousands of pictures of the small intestine, which are "beamed" to a set of leads attached to the patient and downloaded onto a computer hard drive. For patients whose mucosal lesions of the upper gastrointestinal tract are not identified by routine endoscopy, video capsule endoscopy can identify bleeding lesions more distally throughout the jejunum and ileum (Item C146A). Ultrasonography can identify varices, but is insensitive for ulcers. Angiography sometimes is useful in patients who have bleeding ulcers that cannot be identified or treated endoscopically. Barium studies are insensitive in evaluating gastrointestinal hemorrhages. Question 162 nuclear medicine gallbladder emptying scan with fatty meal The colicky abdominal pain in the right upper quadrant after the ingestion of fatty foods described for the patient in the vignette is strongly suggestive of gallbladder disease. However, results of laboratory studies and abdominal ultrasonography are within normal limits. Because of the symptom profile, the possibility of chronic acalculous cholecystitis with gallbladder dysmotility should be considered, and the test of choice to evaluate for this condition is a radionuclide gallbladder emptying scan. If the patient has markedly delayed gallbladder motility, consideration should be given to performing a cholecystectomy. Classically, cholecystitis occurs when the gallbladder is inflamed and irritated by gallstones. Such gallstones typically are classified as cholesterol stones and pigment (bilirubin) stones. Risk factors for cholesterol stones include older age, female sex, pregnancy, and overweight. Risk factors for pigment stones include parenteral nutrition and hemolysis (as seen in children who have sickle cell disease). For patients who have stones, cholecystitis commonly presents with pain in the right upper quadrant, epigastrium, and back. Fever, jaundice, and abnormal liver enzyme values also may be present, especially if a gallstone is in the biliary tree (choledocholithiasis). Children may have biliary symptoms without gallstones, a condition termed chronic acalculous cholecystitis or gallbladder dysmotility. Such patients have right upper quadrant pain with meals, but laboratory and ultrasonography results are normal. Hepatobiliary scintigraphy demonstrates delayed emptying of the gallbladder in response to a fatty meal. These children may experience significant symptomatic relief after cholecystectomy; some case series have reported improvement in up to 90% of patients after surgery. Abdominal computed tomography and endoscopic retrograde cholangiography should be considered if pancreatic disease is suspected, but these are not routine tests used to evaluate gallbladder dysmotility. Some patients who have chronic abdominal pain may benefit from psychiatric evaluation or acupuncture, but these measures are more supportive than diagnostic. Question 177 are nonspecific The patient described in the vignette underwent a small bowel biopsy to evaluate chronic diarrhea and weight loss. Although the patient has a positive antigliadin immunoglobulin G, the antibodies that are most sensitive and specific for celiac disease (anti-tissue transglutaminase and anti-endomysial) are both negative. The biopsy findings described in the vignette suggest intestinal injury, but are nonspecific. They do not distinguish between celiac disease, allergy, and infectious enteritis.
  7. 7. Intestinal small bowel biopsy of the duodenum or jejunum remains one of the most useful tests in the evaluation of a child who has chronic diarrhea or suspected malabsorption. Usually intestinal biopsy is performed by passing an endoscope into the duodenum and taking multiple tissue samples with a biopsy forceps. The samples can be evaluated by the pathologist to assess mucosal architecture and to look for specific infectious pathogens (eg, Giardia lamblia, Cryptosporidium). Biopsy findings associated with celiac disease typically show varying degrees of villous atrophy and increased intraepithelial lymphocytes. In contrast, increased eosinophils in the intestinal lamina propria can be seen in children who have allergic enteritis. If necessary, a more detailed evaluation of the intestinal biopsy can be performed with special studies. Immunostaining can identify populations of inflammatory cells, thereby thereby further characterizing autoimmune disease, immunodeficiency syndromes, or neoplastic cells. Electron microscopy can look for small pathogens such as microsporidia and identify ultrastructural abnormalities such as microvillous inclusion disease. In spite of its usefulness, intestinal small bowel biopsy has many limitations. Many intestinal lesions are "patchy, " meaning some biopsy specimens may be normal while others are inflamed. For this reason, multiple (two to five) duodenal biopsies are preferred to minimize sampling error. The biopsy should be interpreted by an experienced gastrointestinal pathologist because minor degrees of inflammation are common in "normal" biopsies. Many findings, such as the increased cellularity and villous atrophy described in the vignette, are nonspecific indications of inflammation and can be seen in many different diseases (including celiac disease (Item C177A), allergic enteropathy [eg, milk protein allergy], autoimmune enteropathy, and viral infection [eg, rotavirus infection]). Thus, although small bowel biopsy is an excellent tool to determine whether there is any intestinal mucosal damage, it does not always provide a specific diagnosis and must be interpreted in the context of the clinical and laboratory findings.