Initial Management of Small Bowel Obstruction
The initial management of small bowel obstruction (SBO) should include nil per os status, nasogastric tube decompression, intravenous crystalloid fluid resuscitation, electrolyte monitoring and correction, and Foley catheter insertion, while actively assessing for signs of peritonitis, strangulation, or ischemia that would require emergency surgery. 1
Initial Assessment
- The primary goal in initial assessment is to identify indications for emergent surgical exploration, including signs of peritonitis, strangulation, and ischemia 2
- Physical examination should include checking for abdominal distension (positive likelihood ratio of 16.8), abnormal bowel sounds, and thorough examination of all hernia orifices 1
- Laboratory tests should include complete blood count, CRP, lactate, electrolytes, BUN/creatinine, and coagulation profile 2
- Elevated CRP, leukocytosis with left shift, and elevated lactate may indicate peritonitis or bowel ischemia, although normal values cannot exclude ischemia 2, 1
Diagnostic Imaging
- CT scan is the preferred initial imaging technique for SBO diagnosis with high sensitivity and specificity 1, 3
- CT provides crucial information about the location, grade, and potential causes of obstruction, and can predict the need for emergency surgery 1, 3
- Plain abdominal radiographs have limited diagnostic value with sensitivity of only 60-70% 2, 1
- Water-soluble contrast agents (WSCA) have both diagnostic and therapeutic value 2, 4
- The appearance of contrast in the colon within 4-24 hours after administration has 96% sensitivity and 98% specificity in predicting successful non-operative management 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 3
Non-operative Management
- Non-operative management is effective in approximately 70-90% of patients with SBO 1, 4
- Key components include:
- Nil per os (NPO) status to reduce intestinal workload 4, 3
- Nasogastric tube decompression to relieve distension and vomiting 1, 3
- Intravenous crystalloid fluid resuscitation to maintain hydration 1, 4
- Electrolyte monitoring and correction to prevent imbalances 1, 4
- Foley catheter insertion for accurate fluid balance monitoring 1
- Water-soluble contrast agents can reduce the need for surgery and improve success rates of non-operative management 4
- In patients with partial obstruction but no signs of strangulation, conservative management resolves the obstruction in approximately 79% of cases 5
Indications for Surgical Intervention
- Immediate surgical intervention is required for:
- The presence of free intraperitoneal fluid, mesenteric edema, absence of the "small bowel feces sign," and a history of vomiting are independent predictors of the need for operative exploration 6
- The combination of these four factors has a sensitivity of 96% and a positive predictive value of 90% for requiring exploration 6
Monitoring and Complications
- Regular reassessment is essential to determine if surgical intervention becomes necessary 4
- Monitor for common complications including:
- Recurrence of intestinal obstruction due to adhesions is possible after non-surgical management, with 12% of patients being readmitted within 1 year 4, 3
- Water-soluble contrast agents may further dehydrate patients due to their higher osmolarity, shifting fluids into the bowel lumen 3
Special Considerations
- For malignant bowel obstruction, surgical intervention after CT scan is the primary treatment option for patients with longer life expectancy 3, 7
- For patients with advanced malignancy, medical management may include pharmacologic measures, parenteral fluids, endoscopic management, and somatostatin analogs 3, 7
- The use of adhesion barriers can reduce recurrence rates in SBO caused by adhesions 4
- Antiemetics that increase gastrointestinal motility should not be used in patients with complete obstruction but may be beneficial in partial obstruction 3