What is the management approach for small bowel obstruction?

Management of Small Bowel Obstruction

The management of small bowel obstruction should begin with non-operative treatment in most patients, unless there are signs of peritonitis, strangulation, or bowel ischemia which require immediate surgical intervention. 1

Initial Assessment and Diagnosis

Clinical Evaluation

• Key clinical findings to assess:
  • Abdominal distension (strong predictive sign with positive likelihood ratio of 16.8) 1
  • Nausea and vomiting (more prominent in small bowel obstruction)
  • Peritonism signs (associated with ischemia/perforation)
  • Examination of all hernia orifices and previous surgical scars
  • Vital signs (tachycardia, tachypnea may indicate shock)

Laboratory Tests

• Complete blood count
• Renal function and electrolytes
• Liver function tests
• Coagulation profile
• Indicators of ischemia: low serum bicarbonate, low arterial pH, high lactic acid, marked leukocytosis 1

Imaging

• CT scan is the preferred imaging technique when diagnosis is uncertain or to assess need for urgent surgery 1

  • Can differentiate complete from partial obstruction
  • Identifies location of obstruction
  • Detects signs requiring immediate surgery: closed loop, bowel ischemia, free fluid
  • Enhanced diagnostic value with water-soluble contrast

• Plain abdominal X-ray:

  • Diagnostic in 50-60% of cases
  • Inconclusive in 20-30%
  • Misleading in 10-20% 1

• Water-soluble contrast studies:

  • Useful for diagnostic and therapeutic purposes
  • If contrast doesn't reach colon within 24 hours, indicates failure of non-operative management 1

Management Algorithm

Non-operative Management (First-line approach)

Non-operative management should be attempted in all patients without signs of peritonitis, strangulation, or bowel ischemia 1. This includes:

1. Bowel rest (nil per os)
2. Decompression:
   • Nasogastric tube decompression
   • Effective in 70-90% of patients with ASBO 1
   • Consider long intestinal tube if available (may be more effective in some cases)
3. Fluid resuscitation with intravenous crystalloids
4. Electrolyte correction
5. Nutritional support as needed
6. Prevention of aspiration

Duration of Non-operative Management

• A 72-hour period is considered safe and appropriate for non-operative management trial 1
• Continuing beyond 72 hours with persistent high output from decompression tube remains debatable
• Delays in surgery can increase morbidity and mortality if obstruction doesn't resolve 1

Indications for Immediate Surgery

• Peritonitis
• Evidence of strangulation
• Bowel ischemia
• Clinical deterioration (fever, leukocytosis, tachycardia, metabolic acidosis, continuous pain) 2
• Ischemic signs on imaging

Surgical Approach

• Laparotomy has been the standard treatment
• Laparoscopic approach may be beneficial for selected cases of simple ASBO 1
  • Benefits: less adhesion formation, earlier return of bowel movements, reduced post-operative pain
  • Caution: higher risk of bowel injuries (6.3-26.9% of patients) 1
  • Best candidates: ≤2 previous laparotomies, history of appendectomy, no previous median laparotomy, single adhesive band 1

Special Considerations

Small Bowel Obstruction in Virgin Abdomen

• Recent evidence suggests adhesions are also a common cause in patients without previous surgery
• These patients can be treated according to the same guidelines as those with adhesive SBO 1

Malignant Bowel Obstruction

• Requires additional considerations including palliative care options
• May benefit from endoscopic stenting or decompression in select cases 3

Complications to Monitor

• Dehydration with kidney injury
• Electrolyte disturbances
• Malnutrition
• Aspiration
• Pneumonia and respiratory failure (increased risk with nasogastric tube placement) 4

Pitfalls to Avoid

1. Delaying surgery when signs of strangulation or ischemia are present
2. Prolonged non-operative management beyond 72 hours without improvement
3. Inappropriate patient selection for laparoscopic approach
4. Failure to recognize clinical deterioration during non-operative management
5. Routine use of nasogastric decompression in patients without active emesis (associated with increased risk of pneumonia and respiratory failure) 4

By following this evidence-based approach to small bowel obstruction management, clinicians can optimize outcomes while minimizing morbidity and mortality associated with this common surgical emergency.