What is the appropriate evaluation and initial management for a patient presenting with abdominal distension?

Evaluation and Initial Management of Abdominal Distension

Begin with immediate assessment of hemodynamic stability and examination for peritoneal signs, as abdominal distension with hypotension, tachycardia, or peritonitis indicates a surgical emergency requiring urgent intervention. 1

Immediate Clinical Assessment

Vital Signs and Hemodynamic Status

• Check for shock indicators immediately: tachycardia, hypotension (systolic BP <90 mmHg), cool extremities, altered mental status, and oliguria, as these suggest bowel ischemia, perforation, or volvulus requiring emergent surgery 1, 2
• Measure blood pressure in both sitting and standing positions to assess volume status 1
• Abnormal vital signs should trigger immediate IV crystalloid resuscitation and surgical consultation 1, 2

Focused Physical Examination

• Assess for peritoneal signs: involuntary guarding, rebound tenderness, and rigidity indicate peritonitis and mandate immediate surgical exploration 1, 3
• Evaluate jugular venous distension (JVD): the most reliable sign of volume overload, assess both at rest and with abdominal pressure (hepatojugular reflux) 1
• Examine all hernia orifices (umbilical, inguinal, femoral) and surgical scars, as incarcerated hernias are a common cause of obstruction 1
• Perform digital rectal examination to detect blood (suggesting malignancy or ischemia) or rectal mass 1
• Palpate for "ballotable fluid" between abdominal wall and liver surface, which indicates significant ascites warranting therapy 1
• Note the onset pattern: sudden onset suggests volvulus, progressive suggests malignancy 1

Critical Red Flags Requiring Emergency Surgery

• Peritoneal signs (guarding, rigidity, rebound tenderness) 1, 2
• Hemodynamic instability despite fluid resuscitation 1, 2
• Feculent nasogastric aspirate (indicates distal obstruction) 1
• Absent bowel sounds or high-pitched "tinkling" sounds 1, 2

Essential Laboratory Workup

Obtain complete blood count, comprehensive metabolic panel, serum lactate, liver function tests, and coagulation studies immediately. 1, 2, 3

• Serum lactate is critical: elevated lactate with metabolic acidosis indicates bowel ischemia with up to 25% mortality if untreated 1, 2
• Marked leukocytosis (>10,000/mm³) suggests ischemia or perforation 1, 4
• Low serum bicarbonate and low arterial pH indicate intestinal ischemia 1
• Hyperamylasemia may indicate intestinal ischemia 1
• BUN/creatinine ratio assesses pre-renal acute renal failure from volume depletion 1
• Coagulation profile is essential given potential need for emergency surgery 1

Immediate Diagnostic Imaging

CT abdomen/pelvis with IV contrast is mandatory and should be obtained immediately, as it has >90% diagnostic accuracy for detecting obstruction and life-threatening complications. 1, 2

CT Protocol

• Do NOT administer oral contrast: it delays diagnosis, increases aspiration risk, causes patient discomfort, and masks abnormal bowel wall enhancement indicating ischemia 1, 2
• Use IV contrast only (unless contraindicated) 1, 2
• CT identifies transition point, etiology, grade of obstruction, and complications with 87-90% accuracy 1, 2

Critical CT Findings Requiring Emergency Surgery

• Signs of ischemia: abnormal bowel wall enhancement (decreased or increased), intramural hyperdensity on non-contrast images, bowel wall thickening, mesenteric edema, pneumatosis intestinalis, or mesenteric venous gas 1, 2
• Closed-loop obstruction 1, 2
• Volvulus 1, 2
• Pneumoperitoneum with free fluid 1, 2
• Intraparenchymal contrast pooling with ruptured capsule (indicates active hemorrhage) 1

Alternative Imaging (Only if CT Unavailable)

• Abdominal plain X-ray has only 50-60% sensitivity for small bowel obstruction and 84% sensitivity for large bowel obstruction—inadequate for excluding ischemia 1, 2
• FAST ultrasound can detect free fluid but cannot identify bowel injury or ischemia; requires ≥400-620 mL fluid to be detected 1
• Water-soluble contrast enema has 96% sensitivity and 98% specificity for large bowel obstruction but cannot distinguish causes 1

Initial Resuscitation and Supportive Care

Begin aggressive IV crystalloid resuscitation immediately with isotonic dextrose-saline or balanced crystalloids containing supplemental potassium. 1, 2, 4

• Replace volume equivalent to patient's losses 1, 2
• Insert Foley catheter to monitor urine output as a marker of adequate resuscitation 1, 2, 4
• Place nasogastric tube for decompression to prevent aspiration pneumonia and decompress proximal bowel 1, 2, 4
• Administer anti-emetics 1, 4
• Enforce strict bowel rest (NPO) 1, 2, 4
• Administer broad-spectrum IV antibiotics covering gram-negatives and anaerobes if systemic signs present 2, 3

Surgical Consultation and Decision Algorithm

Consult surgery immediately upon presentation—do not delay for imaging results if patient is unstable. 1, 2

Immediate Laparotomy Indications

• Peritoneal signs (guarding, rigidity, rebound) 1, 2, 4
• Hemodynamic instability despite resuscitation 1, 2, 4
• CT evidence of bowel ischemia 1, 2
• Closed-loop obstruction 1, 2
• Pneumoperitoneum with free fluid 1, 2
• Volvulus 1, 2
• Clinical deterioration during observation 2, 4

Conservative Management Criteria (Only if ALL Present)

• Hemodynamically stable 2, 4
• No peritoneal signs 1, 4
• No CT evidence of ischemia or closed-loop obstruction 2, 4
• Partial obstruction (patient passing gas) 4
• History of prior abdominal surgery (adhesive obstruction) 4

If conservative management chosen, monitor every 3-6 hours for deterioration: persistent tachycardia, worsening pain, progressive leukocytosis, elevated lactate, or hypotension mandate immediate surgery 4

Special Diagnostic Considerations

Ascites-Related Distension

• Ascites from cirrhosis requires aldosterone antagonist (spironolactone) as first-line therapy 1
• Large-volume paracentesis or TIPS reserved for tense ascites compromising respiratory function 1
• Rapid ascites accumulation suggests portal/hepatic vein obstruction or bacterial peritonitis 1

Trauma-Related Distension

• FAST scan in hypotensive trauma patients has 87-100% sensitivity for detecting free fluid requiring laparotomy 1
• Abdominal distension with positive FAST in unstable patient mandates immediate trauma laparotomy 1
• CT with IV contrast identifies hollow viscus and mesenteric injuries in stable patients 1

Functional Bloating/Distension (Chronic Presentation)

• Diagnosis requires Rome IV criteria and exclusion of organic disease 5, 6
• Treatment includes low FODMAP diet, probiotics, antispasmodics (otilonium bromide, peppermint oil), rifaximin, and biofeedback 5, 6, 7

Critical Pitfalls to Avoid

• Never delay CT imaging in favor of plain radiographs, as plain films miss ischemia and have inadequate sensitivity 1, 2
• Never rely on physical examination alone to exclude ischemia—sensitivity is only 48% 1, 4
• Never delay surgical consultation when red flags present, as delay significantly increases mortality 1, 2, 4
• Never withhold adequate fluid resuscitation before surgery, as hypovolemia worsens outcomes 1, 2
• Never attempt prolonged conservative management with peritonitis, strangulation, or ischemia signs 2, 4
• Never administer oral contrast in suspected bowel obstruction 1, 2
• Never discharge patients with unexplained distension without 24-hour follow-up plan 3