What is the initial treatment approach for acute intestinal obstruction of the small bowel?

Initial Management of Acute Small Bowel Obstruction

The initial management of acute small bowel obstruction should be conservative with analgesia, intravenous fluids, nutritional support, and nasogastric aspiration unless there is suspicion of strangulation requiring emergency surgery. 1, 2

Initial Assessment and Diagnosis

• Thorough evaluation should focus on identifying signs of peritonitis, strangulation, or ischemia, which would require emergency surgical intervention 1, 2
• Physical examination should include assessment of abdominal distension (positive likelihood ratio of 16.8), abnormal bowel sounds, and examination of all hernial orifices 2
• Laboratory tests should include complete blood count, C-reactive protein, lactate, electrolytes, BUN/creatinine, and coagulation profile 1
• Elevated C-reactive protein, leukocytosis with left shift, and elevated lactate may indicate peritonitis or intestinal ischemia requiring urgent surgical intervention 1, 2
• CT scan with intravenous contrast is the preferred imaging technique with superior diagnostic accuracy (>90%) compared to conventional radiography (50-60% sensitivity) 1, 2

Non-Operative Management

• Non-operative management is effective in approximately 70-90% of patients with intestinal obstruction due to adhesions 1, 2
• Key components of conservative management include:
  • Nil per os (NPO) status 1, 2
  • Nasogastric tube decompression to reduce vomiting and improve respiratory status 1, 3
  • Intravenous fluid resuscitation with crystalloids 1, 3
  • Electrolyte monitoring and correction 1, 2
  • Foley catheter insertion to monitor urine output 3, 2
  • Analgesia for pain control 4
• Water-soluble contrast agents (WSCA) can have both diagnostic and therapeutic value 4, 1
  • If contrast reaches the colon within 4-24 hours, this predicts successful non-operative management 1, 2
  • If contrast has not reached the colon on an abdominal X-ray 24 hours after administration, this indicates a high likelihood of non-operative management failure 1

Indications for Surgical Intervention

• Immediate surgical intervention is required for:
  • Signs of peritonitis 1, 2
  • Suspected strangulation or intestinal ischemia 4, 1
  • Closed-loop obstruction on imaging 1, 2
  • Failure of non-operative management after 72 hours 1, 2
  • Hypotension in the setting of SBO (surgical emergency indicating likely bowel compromise) 3

Surgical Approach

• Laparotomy has traditionally been the surgical approach of choice for SBO 4
• Laparoscopy may be considered in selected patients with the following considerations:
  • Requires surgeons to have a low threshold for conversion to laparotomy 5
  • May result in earlier return of bowel function and shorter postoperative length of stay 5
  • Associated with a risk of bowel injury (reported in 9% of cases) 6
  • May be limited by inadequate visualization due to bowel distention 5, 6
• Hypotensive patients generally require laparotomy due to better visualization and faster bowel assessment 3

Potential Complications and Pitfalls

• Common complications include:
  • Dehydration with renal injury 1, 2
  • Electrolyte disturbances 1, 2
  • Malnutrition 1
  • Aspiration pneumonia 2
• Avoid delaying surgical intervention in patients with signs of peritonitis, strangulation, or ischemia 3
• Water-soluble contrast agents may further dehydrate patients due to their higher osmolarity, shifting fluids into the bowel lumen 1
• Recurrence of intestinal obstruction is possible after non-operative management (12% within 1 year, increasing to 20% after 5 years) 1

Special Considerations

• For malignant bowel obstruction, surgery after CT scan is the primary treatment option for patients with longer life expectancy 1
• For patients with advanced disease or poor condition, medical management may include pharmacologic measures, parenteral fluids, endoscopic management, and enteral tube drainage 1
• Antiemetics that increase gastrointestinal motility should not be used in patients with complete obstruction but may be beneficial in partial obstruction 1