Small Bowel Obstruction Management
Immediate Resuscitation and Initial Assessment
Begin immediate aggressive IV crystalloid resuscitation, insert a nasogastric tube for decompression, and obtain urgent CT abdomen/pelvis with IV contrast (without oral contrast) while simultaneously assessing for signs of peritonitis, strangulation, or ischemia that mandate emergency surgery. 1
Critical First Steps (Within Minutes of Presentation)
- Start aggressive intravenous crystalloid resuscitation immediately—patients are profoundly dehydrated from third-spacing, bowel wall edema, and vomiting 1
- Insert a Foley catheter to monitor urine output as a direct marker of adequate resuscitation 1
- Place a nasogastric tube for gastric decompression to reduce aspiration risk, improve respiratory mechanics, and remove proximal intestinal contents 1
- Initiate broad-spectrum IV antibiotics immediately if systemic signs are present (fever, hypotension, peritonitis), covering gram-negative organisms and anaerobes 1
Essential Laboratory Workup
- Obtain complete blood count, serum lactate, comprehensive metabolic panel, and C-reactive protein as the minimum essential panel 1
- Serum lactate is critical for detecting bowel ischemia, which carries up to 25% mortality if present 1
- Elevated lactate with leukocytosis and metabolic acidosis indicates probable bowel ischemia and mandates immediate surgical exploration 1
- Monitor electrolytes for abnormalities from vomiting and third-spacing, and assess BUN/creatinine for acute kidney injury 1
Urgent Diagnostic Imaging
CT abdomen/pelvis with IV contrast is mandatory and should be obtained immediately, as it has >90% accuracy for detecting small bowel obstruction and identifying life-threatening complications. 1
CT Protocol and Interpretation
- Do not administer oral contrast—it delays diagnosis, increases patient discomfort, risks aspiration, and can mask abnormal bowel wall enhancement that indicates ischemia 1
- Look specifically for CT signs of ischemia: abnormal bowel wall enhancement, intramural hyperdensity, bowel wall thickening, mesenteric edema, pneumatosis, or mesenteric venous gas 1
- CT identifies the transition zone, etiology, and grade of obstruction with 87-90% accuracy 1
- Plain abdominal radiographs have only 60-70% sensitivity and cannot exclude small bowel obstruction or detect ischemia—do not rely on them 2, 1
- MRI is a valid alternative in children and pregnant women with 95% sensitivity and 100% specificity 2
Surgical Decision-Making Algorithm
Immediate Emergency Surgery Required For:
- Signs of peritonitis on examination 2, 1
- Hemodynamic instability or hypotension despite resuscitation 1
- CT evidence of bowel ischemia, closed-loop obstruction, or pneumoperitoneum with free fluid 1
- Free perforation with pneumoperitoneum and free fluid 2
- Clinical deterioration markers: persistent fever, rising lactate, worsening leukocytosis 2
Non-Operative Management Appropriate For:
Non-operative management successfully resolves 70-90% of adhesive small bowel obstruction cases and should be attempted in hemodynamically stable patients without peritoneal signs or imaging evidence of ischemia. 2, 1
Essential Components of Conservative Management:
- Nothing by mouth (NPO) status 2
- Nasogastric tube decompression (or long intestinal tube if available, which is more effective but requires endoscopic insertion) 2
- Intravenous crystalloid fluid resuscitation 2
- Electrolyte monitoring and correction 2
- Administer 100 mL water-soluble contrast agent (Gastrografin) via nasogastric tube after adequate gastric decompression—this has both diagnostic and therapeutic value, significantly reducing need for surgery, time to resolution, and length of stay 2
Monitoring During Conservative Management:
- Serial abdominal examinations to detect development of peritonitis or clinical deterioration 2
- Monitor for contrast reaching colon within 4-24 hours after administration—if contrast reaches colon within 5 hours, there is a 90% resolution rate 2
- Continuously monitor urine output, hemodynamic parameters, nasogastric tube output, and rising lactate levels 2, 1
When to Abandon Conservative Management:
- Surgery is indicated when non-operative management fails after 72 hours—this is considered the safe and appropriate timeframe 2, 1
- Failure of contrast to reach colon within 24 hours after administration predicts need for surgery 2
- Development of any signs of peritonitis, strangulation, or clinical deterioration during observation 2
Surgical Approach Selection
- Laparotomy is preferred over laparoscopy in unstable patients, those with gross ascites, suspected high-grade obstruction, or hemodynamic instability, as it provides better visualization and faster bowel assessment 1
- Laparoscopic approach may be considered in hemodynamically stable patients with single adhesive band identified on CT scan with clear transition point, minimal bowel distension, and no diffuse peritonitis 2
- The risk of iatrogenic bowel injury with laparoscopy is 3-17.6%, and all enterotomies must be identified intraoperatively to avoid missed perforations 2
- Very distended bowel loops are a contraindication to laparoscopy 2
Special Considerations
Small Bowel Obstruction Without Prior Surgery (Virgin Abdomen)
- Adhesions can occur even without prior surgery from congenital bands or unrecognized prior inflammation 2
- Requires heightened suspicion for alternative etiologies including internal hernias, malignancy, bezoars, and in young females, ovarian masses, endometriosis, or pelvic inflammatory disease 2, 1
- Non-operative management with water-soluble contrast is still appropriate and effective in virgin abdomen cases 2
Malignant Bowel Obstruction
- Surgery is the primary treatment for patients with years to months to live after appropriate imaging 2
- For patients with advanced disease or poor condition, medical management is preferable: opioid analgesics, anticholinergic drugs, corticosteroids, and antiemetics 2
- Octreotide is highly recommended early in diagnosis due to high efficacy and tolerability 2
- For left-sided obstructing colon cancer, self-expanding metallic stents are preferred over colostomy for palliation 2
Inflammatory Bowel Disease
- Free perforation is an absolute indication for emergency surgery 2
- Stenoses can be inflammatory or fibrostenotic—patients deserve a trial of medications aimed at reducing inflammation 2
- Endoscopic balloon dilation has 89-92% technical success rate for primary intestinal or anastomotic strictures in Crohn's disease 2
- Any colorectal stricture should be assessed with endoscopic biopsies to rule out malignancy 2
Adhesion Prevention in Young Patients
- Young patients have the highest lifetime risk for recurrent adhesive obstruction and should receive adhesion barriers during surgery to reduce future episodes 2
- Hyaluronate carboxymethylcellulose barriers reduce recurrence from 4.5% to 2.0% at 24 months 2
Recurrence Rates and Long-Term Outcomes
- Recurrence after non-operative management occurs in 12% of cases at 1 year and 20% at 5 years 2
- Recurrence after operative management occurs in 8% of cases at 1 year and 16% at 5 years 2
- Patients treated non-operatively have a significantly shorter time to recurrence (mean 153 days) compared to those treated operatively (mean 411 days) 3
Critical Pitfalls to Avoid
- Delaying CT imaging in favor of plain radiographs—plain films cannot exclude small bowel obstruction or detect ischemia 1
- Relying on physical examination alone to exclude ischemia or strangulation—imaging is mandatory 1
- Delaying surgical consultation when red flags are present—this significantly increases morbidity and mortality 1
- Delaying surgery beyond 72 hours in patients with persistent obstruction increases morbidity and mortality 2
- Inadequate fluid resuscitation before surgery worsens outcomes 1
- Attempting prolonged non-operative management in patients with signs of peritonitis, strangulation, or ischemia 1