How do you manage colonic ileus (acute colonic pseudo‑obstruction)?

Management of Colonic Ileus (Acute Colonic Pseudo-Obstruction)

Begin with immediate supportive care including intravenous fluid resuscitation, correction of electrolyte abnormalities (particularly potassium supplementation of at least 60 mmol/day), discontinuation of all medications that inhibit intestinal motility (opioids, anticholinergics, calcium channel blockers), bowel rest, and mobilization of the patient. 1, 2

Initial Assessment and Risk Stratification

• Obtain plain abdominal radiographs immediately to measure cecal diameter; cecal dilatation >10-12 cm indicates high perforation risk requiring urgent intervention, while dilatation >5.5 cm warrants close monitoring. 3, 4, 2

• Perform CT abdomen and pelvis with IV contrast to exclude mechanical obstruction (transition point, volvulus, internal hernia), assess for bowel ischemia (abnormal wall enhancement, pneumatosis, mesenteric venous gas), and identify underlying causes. 3

• Monitor vital signs four times daily and obtain daily laboratory tests including complete blood count, electrolytes (especially potassium and magnesium), renal function, and inflammatory markers (CRP, lactate). 5, 1

• Exclude infectious causes through stool testing for Clostridioides difficile, bacterial pathogens, and parasites, but do not delay treatment while awaiting results. 4

Conservative Management (First 24-48 Hours)

• Administer IV crystalloid fluids to correct dehydration and maintain adequate urine output. 3, 1

• Correct electrolyte abnormalities aggressively, particularly hypokalemia and hypomagnesemia, as these directly impair colonic motility. 1, 2

• Discontinue all antikinetic medications including opioids, anticholinergics, calcium channel blockers, and phenothiazines. 1, 2

• Insert nasogastric tube if significant nausea, vomiting, or small bowel dilatation is present to decompress the upper GI tract. 3

• Mobilize the patient by encouraging ambulation or repositioning every 2 hours if bedbound; immobility is a major contributing factor. 2, 6

• Provide thromboprophylaxis with subcutaneous low-molecular-weight heparin, as thromboembolic risk is elevated. 5

Pharmacologic Decompression (If Conservative Management Fails After 24-48 Hours)

Administer neostigmine 2-2.5 mg IV over 3-5 minutes as the first-line pharmacologic intervention for patients without contraindications. 1, 2

• Contraindications to neostigmine include: active bronchospasm, bradycardia (heart rate <60 bpm), second-degree or higher heart block, recent bowel anastomosis, mechanical obstruction, suspected perforation, or pregnancy. 2, 7

• Monitor continuously with cardiac telemetry during and for at least 30 minutes after neostigmine administration; have atropine 0.6-1.2 mg IV immediately available to reverse bradycardia. 2, 7

• Expect clinical response within 30 minutes in approximately 80-90% of patients; response is defined as passage of flatus or stool and reduction in abdominal distension. 1, 2

• If no response after 30 minutes, a second dose of neostigmine 2 mg IV may be administered. 2

• Alternative subcutaneous neostigmine regimen (0.25 mg SQ every 6 hours) may be used for patients requiring prolonged therapy or those at higher risk of IV administration complications, though onset is slower (median 29 hours to first bowel movement). 7

Colonoscopic Decompression

Perform colonoscopic decompression if neostigmine fails, is contraindicated, or cecal diameter exceeds 12 cm despite medical management. 1, 2

• Use colonoscopy without bowel preparation to minimize fluid shifts and electrolyte disturbances. 2

• Advance the colonoscope to the cecum or point of maximal dilatation and aspirate luminal gas; avoid excessive air insufflation. 2

• Consider placement of a decompression tube through the colonoscope into the proximal colon to prevent recurrence, though evidence for efficacy is limited. 2

• Success rate of colonoscopic decompression is 70-90%, but recurrence occurs in 40-50% of cases. 2

Surgical Intervention

Proceed immediately to surgery if any of the following are present: peritoneal signs suggesting perforation, CT evidence of pneumoperitoneum, bowel ischemia (lactate >4 mmol/L, pneumatosis, portal venous gas), failure of medical and endoscopic therapy after 48-72 hours, or cecal diameter >12 cm with clinical deterioration. 3, 2, 8

• Subtotal colectomy with end ileostomy is the procedure of choice in the emergency setting; mortality approaches 50% if perforation has occurred versus 6% with intact bowel. 2, 8

• Cecostomy (tube or surgical) may be considered in extremely high-risk surgical candidates, though definitive data supporting this approach are lacking. 2

Management of Recurrent Episodes

For patients with recurrent acute colonic pseudo-obstruction despite appropriate management, consider underlying chronic intestinal pseudo-obstruction or colonic dysmotility disorder requiring specialized motility testing and long-term prokinetic therapy. 3, 2

• Evaluate for chronic conditions including neurologic disorders, endocrine abnormalities (hypothyroidism, diabetes), connective tissue diseases, and chronic medication effects. 3, 2

• Avoid repeat colonoscopic decompressions beyond 2-3 episodes; consider surgical consultation for definitive management. 2

Critical Pitfalls to Avoid

• Do not administer oral contrast agents in suspected high-grade obstruction, as this delays diagnosis, increases aspiration risk, and obscures assessment of bowel wall enhancement. 3

• Do not delay surgical consultation in patients with cecal diameter >12 cm or signs of ischemia; mortality increases dramatically with delayed intervention. 2, 8

• Do not use neostigmine in patients with mechanical obstruction, as this can precipitate perforation; always exclude mechanical causes with imaging first. 1, 2

• Do not overlook opioid-induced bowel dysfunction as a contributing or primary cause; aggressive opioid weaning or use of peripheral mu-opioid antagonists (methylnaltrexone, naloxegol) may be necessary. 3