GI bleeding and abdominal emergencies

Ileus and acute colonic pseudo-obstruction

Reviewed Nov 2026·3 references
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Recognise ICU ileus, exclude mechanical obstruction, correct causes, and treat Ogilvie syndrome with neostigmine or decompression.

Definition
Ileus = functional impairment of gut motility without mechanical obstruction (post-operative, sepsis, opioids, electrolytes). Acute colonic pseudo-obstruction (Ogilvie) = massive colonic dilatation without obstruction; caecal diameter > 10-12 cm raises perforation risk.

At the bedside

  1. 1

    Exclude mechanical obstruction

    Examine hernias and scars; abdominal X-ray and CT (transition point, volvulus, closed loop) if any doubt.

  2. 2

    Correct contributors

    Keep K > 4 mmol/L and Mg > 2 mg/dL, correct phosphate and glucose; reduce opioids (multimodal analgesia), stop anticholinergics, treat sepsis, mobilise early.

  3. 3

    Decompress

    Nasogastric tube for vomiting/gastric distension; rectal tube; avoid feeding into a distended dilated stomach (trickle feeds once tolerated).

  4. 4

    Prokinetics

    Metoclopramide 10 mg IV q8h (upper GI), erythromycin 250 mg IV q8h; for opioid-induced constipation consider methylnaltrexone (where available) or laxatives.

  5. 5

    Ogilvie: neostigmine

    If caecum > 10 cm or no improvement after 24-48 h conservative care and no contraindication: neostigmine 2 mg IV over 3-5 min with cardiac monitoring and atropine ready; patient supine on bedpan.

  6. 6

    Colonoscopic decompression or surgery

    If neostigmine fails/contraindicated: colonoscopic decompression ± tube; surgery for perforation, ischaemia or failure.

  7. 7

    Monitor IAP

    Severe distension can cause IAH/ACS.

Acute colonic pseudo-obstruction

Neostigmine

IV
Dose
2 mg over 3-5 min; repeat once if needed
Worked example
2 mg (4 mL of 0.5 mg/mL) slow IV with ECG monitoring; atropine 0.6 mg drawn up

Expect evacuation within 30 min in responders.

Red flag · call your senior now
Caecal diameter > 12 cm, tenderness, fever or peritonism in pseudo-obstruction: risk of perforation - urgent surgical review.
Pitfall
Giving neostigmine before excluding mechanical obstruction.
Pearl
Most neostigmine responders pass flatus or stool within 30 minutes; recurrence occurs in a minority and a second dose may be given.

References

  1. 1

    Ponec RJ, Saunders MD, Kimmey MB. Neostigmine for the treatment of acute colonic pseudo-obstruction. N Engl J Med 1999;341:137-41.

  2. 2

    Kirkpatrick AW, Roberts DJ, De Waele J, et al. Intra-abdominal hypertension and the abdominal compartment syndrome: updated consensus definitions and clinical practice guidelines from the World Society of the Abdominal Compartment Syndrome. Intensive Care Med 2013;39:1190-206.

  3. 3

    Farkas J. The Internet Book of Critical Care (IBCC). EMCrit Project; continuously updated.

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