Understanding Acute Abdomen. Lacture note for medical students.

1. Acute abdomen
Prof.M K AlamMS; FR CS

2. Learning objectives
 Definition
 Anatomy and physiology of abdominal pain.
 Pathophysiology of common causes of acute abdomen.
 Symptoms and signs of acute abdomen in relation to
the underlying pathology
 Laboratory and imaging investigations
 Initial and definitive management

3. Definition
A clinical presentation of
abdominal pain and tenderness,
that often requires emergency
surgical therapy.

4. • Spectrum of surgical & gynaecological conditions.
• Trivial to life-threatening conditions.
• 50% of general surgical emergencies.
• Some non-surgical or non intra-abdominal diseases.
• 30 days mortality: 4% among patients with abdominal pain
• Every attempt to make a correct diagnosis.
• Appropriate therapy

5. • The primary symptom: Abdominal pain
• Types of abdominal pain:
 Visceral
 Parietal

6. Visceral pain
• Visceral peritoneum invests abdominal viscera
• Shares its nerve supply (autonomic) with the viscera
• Visceral pain mediated through sympathetic ANS
• Visceral peritoneum insensitive to mechanical, thermal or chemical stimuli
• Sensitive to distension, traction on mesentery ,visceral muscle spasm & ischemia
• Visceral pain- dull & deep seated
• Vague, poorly localized
• Localized to the area of development
• Foregut organs- pain localized to epigastrium
• Midgut organs-, pain localized to periumbilical
• Hindgut organs- pain localized to hypogastrium

7. Parietal pain
• Originate from the irritation of parietal peritoneum
• Parietal peritoneum- somatic nerve
• Sensitive to mechanical, thermal & chemical stimulation
• When parietal peritoneum irritated- reflex contraction of
corresponding muscle segment (guarding)
• Pain sharp or knife like
• Well localized to the affected area

8. Referred pain
Definition: Pain perceived at a site distant from
the source of stimulus.
Common examples of referred pain:
Right shoulder- Gall bladder
Left shoulder- Heart, tail of pancreas, spleen (Kehr's sign)
Scrotum and testis- ureter

9. Pain locations (Great degree of overlap)
• Right hypochondrium.- gallbladder
• Left hypochondrium.- pancreas
• Epigastrium.- Stomach and duodenum
• Lumber- kidney
• Umbilical- small bowel, caecum, retroperitoneal
• Right iliac fossa- Appendix, caecum
• Left iliac fossa- Sigmoid colon
• Hypogastrium- Colon, urinary bladder, adenexae

11. Pathogenesis

12. Surgical Causes of Acute Abdominal
• Inflammation: Appendicitis, cholecystitis, pancreatitis
• Perforation- Perforated duodenal ulcer, perforated
diverticulum, perforated appendix, perforated bowel
• Obstruction- Small bowel adhesions, obstructed hernia,
sigmoid volvulus, neoplasms
• Ischemia- Mesenteric ischemia (thrombosis/ embolism)
strangulated hernia
• Hemorrhage- Ruptured ectopic pregnancy, ruptured
aneurysms, solid organ trauma

13. Nonsurgical Causes of Acute Abdomen
• Diabetic crisis
• Uremia
• Hereditary Mediterranean fever
• Sickle cell crisis
• Acute leukemia

14. Common causes of acute abdominal pain
Adults
• Non specific -35%
• Acute appendicitis- 30%
• Ac. Chole./ biliary colic -10%
• PUD- 5%
• Small bowel obstruction - 5%
• Gynaecological disorders -5%
• Ac. Pancreatitis -2%
• Renal/ ureteric colic- 2%
• Malignant disease - 2%
• Acute diverticulitis -2%
• Misc. - 2%
Children
• Acute appendicitis
• UTI
• Mesenteric adenitis
• Gastroenteritis

15. Inflammation
• Types: Infective or Non-infective
• Reactive hyperaemia- arteriolar/ capillary dilatation
• Exudation of fluid- increased vessel permeability
• Migration of leucocytes from vessels
• Clinical effect: depends on severity, duration, organ involved
• Abdominal pain, pyrexia, tachycardia, tenderness, guarding

16. Pathogenesis of Acute appendicitis
• Most common general surgical emergency
• Derived from the midgut
• Obstruction of the lumen (fecalith, lymphoid hyperplasia,
vegetable matter or seeds, parasites)
• Obstruction contributes to bacterial overgrowth,

17. Pathogenesis of Acute appendicitis
• Intraluminal distention.
• Distention produces the visceral pain- periumbilical pain.
• Promote a localized inflammatory process.
• May progress to gangrene and perforation.
• Inflammation of the adjacent peritoneum- localized pain RIF.
• Perforation usually after 48 hours from the onset.

18. Peritonitis
• Introduction of bacteria or irritating chemicals into the peritoneal
cavity by extension of inflammation or perforation of viscus
• Peritoneal inflammation
• Localized inflammation (appendicitis)- sharply localized pain,
normal bowel sounds
• Generalized peritonitis (perforated viscus) -generalized
abdominal pain, quiet abdomen

19. Types of peritonitis
• Primary peritonitis: Uncommon.
Children: Pneumococcus or hemolytic Streptococcus.
Adults: Peritoneal dialysis(gram +ve cocci).,
Ascites and cirrhosis(Escherichia coli and Klebsiella)
• Secondary peritonitis: Common, secondary to inflammatory
insult from within abdomen, most gram-negative infections
(enteric organisms or anaerobes). Example- perf. appendicitis
• Noninfectious : Pancreatitis (chemical peritonitis)

20. Obstruction
• Impedance to normal flow through hollow viscus
• Causes: 1. Lesion within lumen- stone, FB, worms, stool
2. Lesion of the wall- neoplasms, stricture
3. Extrinsic compression-adhesions, hernia
• Viscus contracts to overcome obstruction (colicky pain)
• Proximally- increased intraluminal pressure, dilatation,
back pressure effect- hydronephrosis, bowel ischemia
(infarction, perforation)

21. Aetiology of obstruction

22. Small bowel obstruction
• Post-operative adhesion- most common
• Hernia, tumour, Crohn’s disease- other causes
• Early- the intestinal contraction increases to propel contents past
the obstructing point (colicky pain)
• Later- the intestine becomes fatigued and dilates, contractions
becoming less intense.
• Bowel dilates, water and electrolytes accumulate in lumen and in
the bowel wall.
• Massive third-space fluid loss: dehydration and hypovolemia.
• Intraluminal pressure increases in the bowel, a decrease in mucosal
blood flow occurs.

23. Ischemia
• Occlusion of arterial supply or venous drainage
• Ischaemic coagulative necrosis (infarct)
• Inflammatory response along the margin
• Abdominal pain due to intestinal ischemia- common
• Other causes of ischemic abdominal pain- spleen,
kidney, liver, pancreas and ovaries

24. Mesenteric Ischemia
• Arterial: embolism, thrombosis
• Venous: thrombosis
• Superior mesenteric vessel distribution- most common
• Intestinal mucosal sloughing- within 3 hours of onset
• Full-thickness intestinal infarction by 6 hours

25. Symptoms & Signs
in
Acute abdomen

26. Clinical assessment
• Good history
• Appropriate examination
• Full history and thorough examination (not always possible)
• Rapid evaluation
• Resuscitation

27. Main symptom- Abdominal pain
• Site: finger vs hand, most valuable indicator to underlying diagnosis (4 quadrants, 9 regions)
• Onset: Sudden- perforation, ischemia, biliary colic. Gradual- inflammation
• Severity: Visual analogue scale. Colicky pain- severe.
Inflammatory- initially mild, progress with time
• Progress: worsens over several hours- inflammation or infection
• Nature: Spasmodic: Biliary / ureteric colic. Constant- worse by movement- inflammatory
• Radiation and shift: cholecystitis, appendicitis
• Exacerbating factors: food worsen pain of bowel obstruction
• Relieving factors: food relieves pain- non-perforated PUD, gastritis.

29. Associated symptoms
• Vomiting: pain presents first in acute surgical abdomen. Vomiting
precede significant abdominal pain in medical conditions.
Constipation or obstipation can be a result of either mechanical
obstruction or decreased peristalsis (ileus).
• Diarrhea is associated with several medical causes of acute
abdomen, including infectious enteritis, inflammatory bowel
disease (IBD), and parasitic contamination
• Bloody diarrhea- IBD, Colonic ischemia

30. EXAMINATION
Inspection of the patient
• Ischemic bowel and ureteral and biliary colic, typically
cause patients to continually shift and fidget in bed while
trying to find a position that lessens their discomfort.
• Patients with peritonitis lie very still in the bed during the
evaluation and often maintain flexion of their knees and
hips to reduce tension on the anterior abdominal wall.

31. General Examination
• Vital signs- pulse, BP, temperature, RR
• Anemia
• Jaundice
• Sweating
• Dehydration

32. Inspection of the abdomen
• Distension: Obstruction
• Restricted mobility- ?peritonitis
• Scars of previous surgery- ?adhesion
• Hernias- cough impulse, reducible/irreducible
• Mass effect, distended veins
• Visible peristalsis
• Ecchymosis ? Acute pancreatitis (Cullen’s, Grey Turner’s sign)

33. Palpation of the abdomen
• Gently / deep , away from the area of pain.
• Severity/ location of tenderness- localized/ generalized
• Involuntary guarding
• Organomegaly, any mass
• Murphy’s sign, Rovsing’s sign,
• Rebound tenderness (Blumberg’s sign)

34. Percussion of the abdomen
• Hyperresonance :distended bowel loops
• Dullness due to organomegaly or mass
• Liver dullness lost- free intra-abdominal air is suspected.
• Shifting dullness- fluid
• Tenderness (tap tenderness)

35. Auscultation of the abdomen
• Quiet abdomen- ileus
• Hyperactive bowel sounds- bowel obstruction,
gastroenteritis
• Mechanical bowel obstruction- high-pitched “tinkling”
sounds that come in rushes and are associated with pain
• Bruits- high-grade arterial stenosis

36. Digital rectal examination
• Routine ? selective
• Check for mass, tenderness, or intraluminal blood
• Pelvic examination in female

37. Part 2

38. Investigations

39. Routine laboratory investigations
• Hematology: WBC / differential count, hemoglobin, platelets, RBC, sickle test
• Electrolytes, urea, creatinine, C-reactive protein, ca
• Amylase, lipase
• LFTs: Bilirubin (T & D), alkaline phosphatase, aminotransferase,
• Serum lactate & arterial blood gas
• Urine analysis
• Urine human chorionic gonadotropin
• Stool for parasites

40. • Lactate levels and arterial blood gas: intestinal
ischemia or infarction.
• Urinalysis: bacterial cystitis, pyelonephritis, diabetes.
• Urinary human chorionic gonadotropin: suggest
pregnancy as a factor in the patient's presentation or aid in
decision making regarding therapy.
• Stool: occult blood, parasite, Cl. Difficile (toxin & culture).

41. Plain radiographs
• Upright chest radiographs – free gas under
the dome of diaphragm
Perforated duodenal ulcer-75%
• Lateral decubitus abdominal radiographs-
pneumoperitoneum in patients who cannot
stand

43. Plain x-ray abdomen
• Limited usefulness
• Calcifications: renal stones 90%, chronic pancreatic,
aortic aneurysms, fecalith
• Supine and upright films: distension, fluid levels, gas
distribution (small vs large bowel), volvulus of
sigmoid colon/ cecum

47. Contrast X-ray
• Water soluble contrast
• Oral/ nasogastric- small bowel follow through
• Less specific
• Obstruction/ perforation (rarely used)
• Contrast not reached caecum in 4 hours-
complete obstruction, needs surgery

49. Abdominal ultrasonography
• Gallbladder: stone, wall thickness, fluid around
gallbladder, diameter of bile ducts
• Liver: abscess, other masses
• Pelvis: Ovarian, adnexal & uterine pathologies
• Free fluid in peritoneum
• Limited evaluation of pancreas
• Limitations: bowel gas, person dependent, difficult
to interpret for most surgeons

51. Liver abscess (US)

52. CT abdomen
• Widely available
• Easier to interpret by surgeons
• Imaging modality of choice in acute abdomen,
following plain abdominal radiographs.
• Accuracy and utility of CT abdomen and pelvis
in acute abdominal pain is well established.
• Most common causes of acute abdomen are
readily identified by CT
• Highly accurate in acute appendicitis,
mechanical bowel obstruction, intestinal
ischemia

53. Liver abscess Paracolic abscess

55. DIAGNOSTIC LAPAROSCOPY
• Ability to diagnose and treat a number of the
conditions causing an acute abdomen
• High sensitivity and specificity
• Decreased morbidity and mortality, decreased
length of stay, and decreased overall hospital costs
• Advances in equipment and greater availability

56. DIFFERENTIAL DIAGNOSIS
• Differential diagnosis of acute abdominal pain is extensive.
• Comprehensive knowledge of the medical and surgical
conditions that create acute abdominal pain
• Mild, self-limited illness to the rapidly progressive and fatal
• Evaluated immediately upon presentation and reassessed at
frequent intervals.
• Many acute abdomen require surgical intervention but some
abdominal pain are medical in aetiology.

58. Management

59. Preoperative preparation
• Fluid and electrolyte abnormalities corrected
• Antibiotic infusions for the bacteria common in acute
abdominal emergencies(gram-negative enteric organisms and
anaerobes)
• Nasogastric tube to decrease the likelihood of vomiting
and aspiration
• Foley catheter- to assess urine output -0.5 mL/kg/hour
• Blood typed and cross matched for operation

60. Preoperative preparation
• Frequent evaluation of the patient
• Stabilization of co-morbid conditions
• Surgical vs non- surgical management
• Consent for surgery

61. Surgical intervention
• Excision: Appendectomy, cholecystectomy, tumors.
• Resection and anastomosis: Bowel tumors, gangrenous
bowel,
• Relieve obstruction: Hernia, division of adhesion.
• Repair of perforation: Perforated DU, stomach, ileum
• Drainage: Appendicular abscess.
• Bowel diversion: Colostomy.

62. Non-surgical intervention
• Conservative management: NPO, IV fluid, antibiotics
Example: Appendicular mass
• Radiological intervention: PCD (liver abscess, appendicular abscess),
placing stents in obstructed bowel ( carcinoma colon).
• Endoscopic intervention: Bile duct decompression.
Example : ERCP in cholangitis

63. Common Causes
of
Acute Abdomen

64. Acute appendicitis
• Most common general surgical emergency
• Derived from the midgut
• Obstruction of the lumen (fecalith, lymphoid hyperplasia,
vegetable matter or seeds, parasites) is the major cause of
acute appendicitis.
• Obstruction contributes to bacterial overgrowth,

65. Acute appendicitis
• Continued secretion of mucus leads to intraluminal distention.
• Distention produces the visceral pain sensation as
periumbilical pain.
• Promote a localized inflammatory process
• May progress to gangrene and perforation.
• Inflammation of the adjacent peritoneum- localized pain in the
right lower quadrant.
• Perforation usually occurs after 48 hours from the onset of
symptoms

66. Acute appendicitis- symptoms
• Typical periumbilical pain (activation of visceral afferent neurons)
followed by anorexia and nausea.
• Pain localizes to the right lower quadrant (inflammatory process
progresses to involve the adjacent parietal peritoneum)
• Migratory pain is the most reliable symptom.

67. Acute appendicitis- signs
• Ill looking patient, low grade fever
• Coughing (Dunphy's sign), may cause increased pain
• Tenderness at McBurney’s point, involuntary guarding
• Site of tenderness may vary depending on the position of the
appendix.
• Pain in the right lower quadrant during palpation of the left
lower quadrant (Rovsing's sign)
• Perforated appendicitis: more severe and diffuse abdominal
pain, tenderness and abdominal wall rigidity

68. Acute appendicitis- investigations
• Elevated WBC and neutrophil
• Normal WBC in 10%
• Very high WBC (>20,000/ml)- complicated appendicitis
• Urine analysis- exclude urinary system disease
• Abdominal x-ray- generally not indicated,
? ureteric calculi, small bowel obstruction, perforated ulcer
• Ultrasonography: Appendix of 7 mm or more in anteroposterior
diameter, thick-walled, noncompressible luminal structure in cross
section (target lesion), the presence of an appendicolith
• CT abdomen: appendix > 7mm in diameter, wall thickening,
periappendiceal edema or fluid

70. Surgical treatment (Acute appendicitis)
• Uncomplicated:
Appendectomy - Laparoscopic vs open surgery
• Complicated:
Localized perforation (abscess): percutaneous
drainage under CT or ultrasound guidance
Free perforation (peritonitis): laparotomy vs
laparoscopic appendectomy

72. Perforated peptic ulcer
• 5% of peptic ulcers penetrate through the
duodenal wall into the peritoneal cavity
• Produce chemical peritonitis

73. Clinical features of perforated peptic ulcer
• Sudden onset epigastric pain
• Fever and tachycardia
• Abdominal tenderness, rigidity, rebound tenderness
• Absent bowel sound
• Free air underneath the diaphragm on an upright
chest radiograph.

75. Perforated peptic ulcer- treatment
• Fluid resuscitation
• Early surgery to close the perforation by
laparoscopy or open surgery

76. Small bowel obstruction
• Post-operative adhesion- most common
• Hernia, tumour, Crohn’s disease- other causes
• Early- the intestinal contraction increases to propel contents past
the obstructing point (colicky pain)
• Later- the intestine becomes fatigued and dilates, contractions
becoming less intense.
• Bowel dilates, water and electrolytes accumulate in lumen and in
the bowel wall.
• Massive third-space fluid loss: dehydration and hypovolemia.
• Intraluminal pressure increases in the bowel, a decrease in mucosal
blood flow occurs.

77. Clinical features
• Colicky abdominal pain, nausea, vomiting, abdominal
distention, and a failure to pass flatus and feces-obstipation
• Examination:
Distended abdomen
Surgical scars/ hernia
Hyperactive bowel sounds
Mild abdominal tenderness

78. Investigations
• Tests for fluid & electrolytes abnormality
• Leukocytosis may be found in patients with
strangulation
• Plain x-ray abdomen: dilated bowel loops (supine)
& multiple air-fluid levels (upright)
• Patient in whom the diagnosis is not readily
apparent- CT abdomen

79. Treatment
• Isotonic saline solution such as lactated Ringer's
• Antibiotics-prophylactically
• Nasogastric suction
• Partial intestinal obstruction may be treated
conservatively with resuscitation and tube decompression
• Operative Management:
• Adhesive obstruction- laparotomy & release of adhesions.
• Hernia- operative reduction and repair

80. Mesenteric Ischemia
• Arterial: embolism, thrombosis
• Venous: thrombosis
• Superior mesenteric vessel distribution
• Intestinal mucosal sloughing within 3 hours
• Full-thickness intestinal infarction by 6 hours

81. Symptoms & signs
• Abdominal pain- sudden onset
• Severity- out of proportion to the degree of tenderness
• The pain is colicky, most severe in the mid-abdomen.
• Associated symptoms- nausea, vomiting, and diarrhea
• Physical findings- absent early in the course.
• Later- abdominal distention, tenderness, guarding and
passage of bloody stools.

82. Investigations
• Leukocytosis,
• Acidosis, and
• Elevated amylase and creatine kinase- late
• CT scanning:
Acute arterial mesenteric ischemia-64 to 82%.
Acute mesenteric venous thrombosis- 90%

84. Mesenteric ischemia- treatment
• Fluid resuscitation
• Laparotomy
• Test for viability of bowel
• Resection of infarcted segment
• Anticoagulation for SMV thrombosis

86. Conclusion
• A challenging part of a surgeon's practice.
• Careful history and physical examination remain the
most important part of the evaluation.
• Laboratory investigations and imaging techniques have
improved the diagnostic accuracy
• Surgeon often make the decision to perform surgery
with a good deal of uncertainty
• Morbidity and mortality associated with a delay in the
treatment demand an expeditious approach

87. Thank you!