How to manage suspected bowel obstruction with distended abdomen, nausea, and no bowel movement?

Immediate Diagnostic Approach for Suspected Bowel Obstruction

Yes, order imaging immediately, but CT scan with IV contrast is superior to KUB and should be obtained if available, as it has >90% diagnostic accuracy for bowel obstruction and can identify life-threatening complications like ischemia or perforation. 1, 2

Initial Clinical Assessment

Your patient's presentation—distended abdomen, nausea, vomiting, and no bowel movement for two days—is highly suggestive of mechanical bowel obstruction. 1, 2 Key clinical features to document:

• Absence of flatus (90% sensitive for large bowel obstruction) and absence of bowel movements (80.6% sensitive) 1
• Abdominal distension has a positive likelihood ratio of 16.8 for bowel obstruction 2
• Character of vomit: bilious/green suggests proximal obstruction; feculent suggests distal obstruction 1
• Bowel sounds: hyperactive rushes suggest early obstruction; absent sounds suggest advanced obstruction or peritonitis 1, 3
• Peritoneal signs: tenderness, guarding, or rebound suggests perforation, ischemia, or strangulation requiring emergency surgery 1, 4

Imaging Strategy

CT scan with IV contrast is the gold standard and should be your first-line imaging choice: 1, 2

• Diagnostic accuracy >90% for bowel obstruction 2, 4
• Identifies the transition point between dilated and normal bowel 1
• Detects complications: ischemia (abnormal wall enhancement, pneumatosis, mesenteric venous gas), perforation, closed-loop obstruction 4
• Guides management: differentiates mechanical from functional obstruction and determines need for surgery 1

KUB (plain abdominal X-ray) is inferior but acceptable if CT is unavailable: 1

• Shows dilated bowel loops and air-fluid levels 3
• May reveal classic signs like "coffee bean sign" in sigmoid volvulus 5
• Major limitation: cannot reliably identify ischemia, perforation, or the exact cause of obstruction 1
• Clinical evaluation and laboratory tests have high variability and low specificity, making escalation to CT mandatory whenever available 1

Ultrasound has 90% sensitivity and can be useful, especially if CT is contraindicated, but is operator-dependent 2

Immediate Management While Awaiting Imaging

Start supportive treatment immediately: 2, 4

• IV crystalloid resuscitation: patients are typically significantly dehydrated from vomiting and third-spacing 2, 4
• Nasogastric tube decompression: reduces aspiration risk, relieves proximal pressure, and improves respiratory status 2, 4
• Foley catheter: monitor urine output as marker of adequate resuscitation 2, 4
• NPO (nothing by mouth) and bowel rest 2
• Anti-emetics: use ondansetron or prochlorperazine—avoid metoclopramide as it is contraindicated in obstruction and can worsen mechanical obstruction or cause perforation 2

Laboratory Tests to Order

• Complete blood count: marked leukocytosis >10,000/mm³ suggests inflammation, infection, or ischemia 2
• Lactate level: elevated lactate indicates potential intestinal ischemia and mandates urgent surgical evaluation 1, 2
• Electrolytes and renal function: assess for dehydration, metabolic alkalosis from vomiting 1
• C-reactive protein: elevated suggests inflammation 3

Red Flags Requiring Emergency Surgery

Do not delay surgical consultation if any of these are present: 1, 2, 4

• Signs of peritonitis (guarding, rebound tenderness, absent bowel sounds) 1
• Hemodynamic instability or hypotension 4
• Elevated lactate suggesting ischemia 2
• CT findings of ischemia, perforation, closed-loop obstruction, or free air 4
• Failed conservative management after 24-48 hours in adhesive obstruction 2

Common Pitfalls to Avoid

• Ordering only KUB when CT is available: KUB cannot detect ischemia or perforation, leading to delayed diagnosis of surgical emergencies 1, 2
• Using prokinetic agents like metoclopramide: these are contraindicated and dangerous in mechanical obstruction 2
• Giving enemas: contraindicated as they increase perforation risk 2
• Delaying surgery in patients with peritonitis or ischemia: mortality increases to 25% with delayed intervention 2, 4
• Excessive fluid administration: after initial resuscitation, avoid worsening intra-abdominal hypertension 4

Special Considerations

In elderly patients with sudden onset lower abdominal pain and distension, consider sigmoid volvulus, which may show the pathognomonic "coffee bean sign" on X-ray but still requires CT confirmation. 5 If confirmed without peritonitis, endoscopic decompression is first-line (70-80% success rate), but elective surgery should follow to prevent recurrence. 5