What is the initial management for a patient suspected of having ileus (ileus) versus partial small bowel obstruction (SBO)?

Management of Suspected Ileus versus Partial Small Bowel Obstruction

Immediate Resuscitation and Stabilization (Same for Both)

Both ileus and partial SBO require immediate aggressive IV crystalloid resuscitation, nasogastric tube decompression, and NPO status, but the critical distinction is that partial SBO demands urgent CT imaging with IV contrast to exclude high-grade obstruction or ischemia, whereas ileus is primarily a clinical diagnosis managed conservatively. 1, 2, 3

• Begin aggressive intravenous crystalloid resuscitation immediately—patients are typically significantly volume depleted from third-spacing and vomiting 1, 4
• Insert a nasogastric tube for gastric decompression to reduce vomiting risk, prevent aspiration, and improve respiratory mechanics 1, 2, 3
• Place a Foley catheter to monitor urine output as a marker of adequate resuscitation 1, 2
• Make the patient NPO (nothing by mouth) 2, 3
• Correct electrolyte abnormalities, particularly potassium, which is frequently depleted 2

Diagnostic Imaging: The Critical Decision Point

CT abdomen and pelvis with IV contrast is mandatory for suspected partial SBO and has >90% diagnostic accuracy for detecting obstruction, identifying the transition point, determining severity, and detecting life-threatening complications like ischemia. 5, 1, 2, 6

• Do NOT give oral contrast in suspected high-grade SBO—it delays diagnosis, increases aspiration risk, causes patient discomfort, and can mask abnormal bowel wall enhancement indicating ischemia 1
• CT with IV contrast distinguishes partial from complete obstruction, identifies the etiology (adhesions, hernias, masses), and detects complications requiring immediate surgery 5, 1, 6
• Signs on CT mandating immediate surgical exploration include: abnormal bowel wall enhancement, closed-loop obstruction, mesenteric edema, free fluid, pneumatosis intestinalis, mesenteric venous gas, or bowel wall thickening with hyperdensity 1, 2, 4
• Plain abdominal radiographs have only 50-70% sensitivity and cannot exclude obstruction or detect ischemia—they should not delay CT imaging 5, 2, 3

For suspected ileus (postoperative setting, medication-induced, metabolic causes), imaging is less urgent unless clinical deterioration occurs or the diagnosis is uncertain. 2, 7

• Ileus is primarily a clinical diagnosis based on recent surgery, opioid use, electrolyte abnormalities, or systemic illness 2, 7
• Serial abdominal exams showing persistent dilated loops with air-fluid levels and paucity of colonic gas favor SBO over ileus 5
• If ileus versus partial SBO cannot be distinguished clinically, obtain CT with IV contrast 5, 2

Management Algorithm: Conservative versus Surgical

For Partial SBO (No Signs of Ischemia or Peritonitis)

Initial conservative management is safe for partial SBO without signs of strangulation, but surgery is indicated if no resolution occurs within 72 hours or if clinical deterioration develops. 3, 8

• Continue nasogastric decompression, IV fluids, and serial abdominal exams 3, 8
• Administer water-soluble contrast medium (50-150 mL orally or via NGT) within the first 24-48 hours—this has both diagnostic and therapeutic value 2, 3
• If water-soluble contrast appears in the colon on X-ray within 24 hours, resolution is predicted and conservative management can continue 3
• Water-soluble contrast reduces need for surgery, time to resolution, and hospital length of stay 3
• If no resolution after 72 hours of conservative management, proceed to surgery 3
• Patients with partial obstruction have a 64-79% chance of resolution with conservative treatment 3, 8

For High-Grade or Complete SBO

Immediate surgical consultation is mandatory, and surgery should not be delayed if signs of ischemia, strangulation, peritonitis, or clinical deterioration are present. 1, 4, 3

• Indications for immediate surgery include: peritonitis on exam, CT signs of ischemia (abnormal enhancement, closed-loop, mesenteric edema, free fluid), hemodynamic instability, or failure to improve with initial resuscitation 1, 4, 3, 6
• Mortality increases from 10% to 25-30% when bowel ischemia or necrosis is present—early surgical intervention is critical 1, 2, 4
• Laparotomy is preferred over laparoscopy in high-grade obstruction or hemodynamically unstable patients due to better visualization and faster assessment 1, 4
• Physical examination alone has only 48% sensitivity for detecting strangulation—imaging is essential 1, 2

For Ileus

Ileus is managed conservatively with bowel rest, nasogastric decompression, IV fluids, correction of electrolytes, and discontinuation of offending medications (opioids, anticholinergics). 2, 7

• Review and stop medications that impair peristalsis, particularly opioids and anticholinergics 2
• Correct metabolic abnormalities (hypokalemia, hypomagnesemia, uremia) 2
• Alvimopan 12 mg PO can be used in postoperative ileus following bowel resection—given preoperatively and continued twice daily for up to 7 days or until discharge 9
• Early ambulation and gradual diet advancement (liquids first, then solids as tolerated) promote resolution 9
• Surgery is NOT indicated for ileus unless perforation or another complication develops 7

Laboratory Tests to Obtain

• Complete blood count—leukocytosis >10,000/mm³ suggests peritonitis 2, 4
• Serum lactate—elevated lactate indicates possible bowel ischemia and mandates immediate surgery 2, 4
• Comprehensive metabolic panel (electrolytes, BUN/creatinine)—assess for dehydration and electrolyte abnormalities requiring correction 2, 4
• C-reactive protein—values >75 mg/L suggest peritonitis, though sensitivity is limited 2, 4
• Type and screen (or crossmatch if surgery likely) 4
• Coagulation studies if patient has liver disease, is anticoagulated, or has bleeding risk factors 4

Common Pitfalls to Avoid

• Delaying CT imaging in favor of plain radiographs—plain films have inadequate sensitivity (50-70%) and cannot detect ischemia 5, 2, 3
• Administering oral contrast in high-grade SBO—this delays diagnosis and risks aspiration 1
• Relying on physical exam alone to exclude ischemia—exam has only 48% sensitivity for strangulation; imaging is mandatory 1, 2
• Prolonging conservative management beyond 72 hours without resolution—this increases morbidity and mortality 3
• Delaying surgical consultation when signs of peritonitis, ischemia, or strangulation are present—mortality increases significantly with delay 1, 4
• Mistaking partial SBO with watery diarrhea for gastroenteritis—"paradoxical diarrhea" can occur with partial obstruction 2
• Inadequate fluid resuscitation before surgery—worsens outcomes 4
• Failing to correct electrolyte abnormalities before surgical intervention—increases complication risk 2