What is the management of small bowel obstruction?

Management of Small Bowel Obstruction

Initial management of acute small bowel obstruction should be conservative with intravenous fluid resuscitation, nasogastric decompression (only if significant vomiting/distension), nil per os status, and electrolyte correction, unless signs of peritonitis, strangulation, or ischemia are present—which mandate immediate surgical intervention. 1

Initial Assessment and Risk Stratification

Your first priority is identifying patients who need emergency surgery versus those suitable for conservative management:

Red flags requiring immediate surgical consultation: 1, 2

• Signs of peritonitis (guarding, rigidity, rebound tenderness)
• Hemodynamic instability/hypotension
• Fever with diffuse abdominal pain
• Elevated lactate, marked leukocytosis with left shift, or elevated C-reactive protein suggesting ischemia
• Free air on imaging indicating perforation

Physical examination specifics: 3

• Assess all hernial orifices (inguinal, femoral, umbilical, incisional)
• Document degree of abdominal distension
• Characterize bowel sounds (absent, hyperactive, or high-pitched)
• Palpate for focal tenderness versus diffuse peritonitis

Essential laboratory tests: 1, 3

• Complete blood count (looking for leukocytosis >15,000 or bandemia)
• Lactate level (>2.5 mmol/L suggests ischemia)
• C-reactive protein
• Comprehensive metabolic panel (electrolytes, BUN/creatinine)
• Coagulation profile if surgery anticipated

Diagnostic Imaging

CT abdomen/pelvis with IV contrast is the gold standard with >90% diagnostic accuracy, far superior to plain radiographs (50-60% sensitivity). 1, 2

CT findings indicating surgical emergency: 2

• Abnormal bowel wall enhancement or lack thereof
• Bowel wall thickening with mesenteric edema
• Pneumatosis intestinalis or mesenteric venous gas
• Closed-loop obstruction
• Free fluid with transition point
• Free intraperitoneal air

Plain radiographs have limited utility and cannot exclude SBO, though they may show dilated small bowel loops with air-fluid levels. 4, 5

Conservative Management Protocol

Approximately 70-90% of adhesive SBOs resolve with non-operative management. 1, 3

Core components of medical management: 1, 6

• NPO status (nothing by mouth)
• IV crystalloid resuscitation targeting urine output >0.5 mL/kg/hr
• Foley catheter for strict intake/output monitoring
• Nasogastric tube decompression—but only if significant vomiting or marked distension present (routine use increases pneumonia risk and hospital length of stay) 7
• Electrolyte monitoring and correction every 6-12 hours
• Analgesia (opioids acceptable despite theoretical concerns about masking peritonitis)
• Serial abdominal exams every 4 hours to detect clinical deterioration

Water-Soluble Contrast Protocol

Gastrografin has both diagnostic and therapeutic value and should be administered in patients without contraindications. 1, 6

Administration protocol: 6

• Give 80 mL Gastrografin mixed with 40 mL sterile water via nasogastric tube
• Obtain abdominal plain films at 4,8,12, and 24 hours
• If contrast reaches colon within 4-5 hours: 90% chance of successful non-operative resolution
• If no contrast in colon by 24 hours: proceed to surgery

Caveat: Water-soluble contrast is hyperosmolar and can worsen dehydration by shifting fluid into bowel lumen—ensure adequate IV hydration before administration. 1

Indications for Surgical Intervention

Absolute indications for immediate surgery: 1, 3, 2

• Clinical peritonitis
• Hemodynamic instability/hypotension despite resuscitation
• Suspected strangulation or intestinal ischemia
• Closed-loop obstruction on CT
• Free perforation with pneumoperitoneum
• Failure of conservative management after 72 hours

Surgical approach: 1, 2

• Laparotomy is preferred in hemodynamically unstable patients, those with diffuse peritonitis, or very distended bowel
• Laparoscopy may be considered in stable patients with single adhesive band on CT and minimal distension, though conversion rates can be high and iatrogenic bowel injury risk is 3-17.6%

In unstable patients with severe sepsis/septic shock: Consider damage control surgery with resection, stapled bowel ends, and temporary abdominal closure (laparostomy). 3

Special Populations and Considerations

Malignant Bowel Obstruction

Surgery after CT is primary treatment for patients with life expectancy of months to years. 1, 3 For advanced disease or poor performance status, medical management includes octreotide (highly effective antiemetic), corticosteroids, anticholinergics, and opioid analgesics. 3

Inflammatory Bowel Disease

Distinguish inflammatory versus fibrostenotic strictures—inflammatory strictures may respond to medical therapy, while symptomatic fibrostenotic strictures require endoscopic dilation (89-92% technical success rate) or surgery. 3 Always biopsy colorectal strictures to exclude malignancy.

Patients Without Prior Surgery ("Virgin Abdomen")

Recent evidence shows adhesions occur even without prior surgery. 3 Water-soluble contrast significantly improves success rates of non-operative management in this population. 3

Common Pitfalls to Avoid

• Delaying surgery in patients with peritonitis, strangulation, or ischemia dramatically increases mortality (10% overall, 30% with bowel necrosis). 5
• Routine nasogastric tube placement in all patients increases pneumonia risk and hospital stay—reserve for those with active vomiting or severe distension. 7
• Attempting prolonged conservative management beyond 72 hours without improvement increases complications. 1, 6
• Inadequate fluid resuscitation before surgery worsens outcomes in hypotensive patients. 2
• Missing closed-loop obstruction on imaging—this requires urgent surgery regardless of clinical stability. 1

Expected Outcomes and Follow-up

Recurrence rates after successful non-operative management: 12% within 1 year, increasing to 20% at 5 years. 1, 3 Young patients have highest lifetime recurrence risk and should receive adhesion barriers (hyaluronate carboxymethylcellulose) during any surgical intervention, reducing recurrence from 4.5% to 2.0% at 24 months. 3

Hospital length of stay: Averages 3 days for successful conservative management versus 11 days for those requiring surgery. 6 Time to contrast reaching colon directly correlates with hospital length of stay. 6