What is the management approach for small bowel obstruction?

Management of Small Bowel Obstruction

Initial Assessment and Risk Stratification

Begin non-operative management immediately for all patients with small bowel obstruction unless signs of peritonitis, strangulation, or ischemia are present—these require emergency surgery. 1, 2

Critical Red Flags Requiring Immediate Surgery

• Peritoneal signs (involuntary guarding, abdominal rigidity, rebound tenderness) 1, 2
• Clinical signs of strangulation: fever, hypotension, diffuse abdominal pain, tachycardia 3, 4
• Closed-loop obstruction on imaging 1, 2
• Free perforation with pneumoperitoneum 2
• Marked leukocytosis with bandemia and lactic acidosis 4

Physical Examination Priorities

• Abdominal distension (positive likelihood ratio 16.8) 1
• Examination of all hernia orifices 1, 2
• Assessment for abnormal bowel sounds 1, 2
• Signs of dehydration and sepsis 4

Essential Laboratory Tests

• Complete blood count, CRP, lactate 1, 2
• Electrolytes, BUN/creatinine 1, 2
• Coagulation profile 1, 2
• Elevated CRP, leukocytosis with left shift, and elevated lactate indicate peritonitis or bowel ischemia 1, 2

Imaging Strategy

CT scan with intravenous contrast is mandatory—plain radiographs are inadequate with only 60-70% sensitivity. 1, 2

• CT identifies obstruction location, grade, and etiology with high sensitivity and specificity 1, 2
• MRI is the alternative for pregnant women and children (95% sensitivity, 100% specificity) 2
• Plain abdominal radiographs cannot exclude the diagnosis and should not be relied upon 3

Non-Operative Management Protocol

This approach succeeds in 70-90% of cases and should be the initial strategy for all patients without surgical red flags. 1, 2, 5

Core Components (Start Immediately)

• Nil per os status 1, 2, 5
• Intravenous crystalloid fluid resuscitation 1, 2, 5
• Electrolyte monitoring and correction every 4-6 hours 1, 2, 5
• Foley catheter for urine output monitoring 1
• Abdominal examinations every 4 hours 6

Nasogastric Tube Decompression—Use Selectively

• Only place nasogastric tubes in patients with significant distension and active vomiting 5, 3
• Routine nasogastric decompression in patients without active emesis increases pneumonia risk, respiratory failure, time to resolution, and hospital length of stay 7
• Nearly 75% of patients without emesis receive unnecessary nasogastric tubes 7

Water-Soluble Contrast Protocol (Gastrografin)

Administer 80 mL Gastrografin with 40 mL sterile water via nasogastric tube—this has both diagnostic and therapeutic value. 6

• Obtain abdominal plain films at 4,8,12, and 24 hours after administration 6
• If contrast reaches the colon within 5 hours, there is a 90% resolution rate 6
• If contrast reaches colon within 4-24 hours, predict successful non-operative management 1, 5
• If contrast does not reach the colon within 24 hours, proceed to surgery 6
• Direct relationship exists between time to pass contrast and hospital length of stay 6
• Water-soluble contrast significantly reduces the need for surgery 1, 2, 5

72-Hour Rule

• Surgery is indicated when non-operative management fails after 72 hours 1, 2, 5
• This timeframe is considered safe and appropriate 2
• Continuous reassessment is essential to detect deterioration requiring earlier intervention 5

Surgical Intervention

Indications

• Failed non-operative management after 72 hours 1, 2, 5
• Any red flag signs (peritonitis, strangulation, ischemia) 1, 2
• Contrast not reaching colon within 24 hours 6
• Clinical deterioration during medical therapy 4

Surgical Approach Selection

• Laparotomy remains the standard approach 2
• Laparoscopic adhesiolysis may be considered in highly selected patients: hemodynamically stable, single adhesive band on CT with clear transition point, minimal bowel distension 2
• Laparoscopy reduces morbidity, mortality, and surgical infections but carries 3-17.6% risk of iatrogenic bowel injury 2
• Conversion rates from laparoscopy to open surgery can be high 2

Adhesion Barrier Use

• Use adhesion barriers in young patients during surgery—reduces recurrence from 4.5% to 2.0% at 24 months 2, 5
• Hyaluronate carboxymethylcellulose barriers are effective 2

Special Populations and Etiologies

Virgin Abdomen (No Prior Surgery)

• Adhesions occur even without prior surgery from congenital bands or unrecognized inflammation 2
• Non-operative management with water-soluble contrast is appropriate and effective 2
• In young females, evaluate for ovarian masses, endometriosis, or pelvic inflammatory disease 2

Malignant Bowel Obstruction

• Surgery is primary treatment for patients with years-to-months life expectancy 2
• Medical management for advanced disease: opioids, anticholinergics, corticosteroids, antiemetics 2
• Octreotide is highly recommended early due to high efficacy and tolerability 2
• Total parenteral nutrition improves quality of life in patients with longer life expectancy 2

Inflammatory Bowel Disease

• Free perforation requires emergency surgery 2
• Endoscopic balloon dilation has 89-92% technical success rate for strictures 2
• Biopsy all colorectal strictures to rule out malignancy 2

Complications to Monitor

• Dehydration with acute kidney injury 1, 2
• Electrolyte disturbances 1, 2
• Aspiration pneumonia (especially with nasogastric tubes) 1, 2, 7
• Malnutrition 1, 2
• Bowel perforation (mortality increases from 10% to 30% with necrosis/perforation) 4

Recurrence Risk

• 12% of patients treated non-operatively are readmitted within 1 year 2, 5
• This increases to 20% after 5 years 2
• Recurrence rates after operative management range 1-10% 2

Common Pitfalls to Avoid

• Do not place routine nasogastric tubes in patients without active vomiting—this increases complications without benefit 7
• Do not rely on plain radiographs for diagnosis—they miss 30-40% of cases 1, 2
• Do not delay surgery beyond 72 hours if non-operative management is failing 1, 2, 6
• Do not attempt laparoscopy with very distended bowel loops 2
• Do not miss all enterotomies during laparoscopic adhesiolysis—unrecognized perforations are catastrophic 2