AKT · Gastroenterology/Acute abdomen & surgical

Colonic pseudo-obstruction (Ogilvie syndrome)

Acute massive colonic dilatation WITHOUT mechanical obstruction (autonomic dysregulation of colonic motility)

Overview

Acute colonic pseudo-obstruction — gross dilatation of the colon (especially caecum and right colon) in the absence of any mechanical obstructing lesion or colitis. Typically in frail, elderly, post-operative or severely unwell patients, often with electrolyte derangement and on opioids/anticholinergics. The danger is caecal perforation, the risk of which rises sharply once the caecum exceeds ~12 cm.

Recognise

Gross, often painless abdominal distension in an elderly/post-op/critically ill patient; may still pass some flatus; tympanic, minimal tenderness
Precipitants: recent surgery (esp. orthopaedic/pelvic), opioids/anticholinergics, electrolyte disturbance (low K/Mg/Ca), sepsis, immobility
Imaging: dilated colon (caecum/right colon) with NO mechanical transition point and NO mucosal inflammation

Red flags

Caecal diameter >12 cm, rising, or present >3–4 days → high perforation risk → active decompression
Peritonism, rising lactate, or free air → ischaemia/perforation → emergency surgery

Differentials & how to tell them apart

Mechanical large bowel obstructiona transition point (obstructing cancer, stricture, volvulus) — pseudo-obstruction has none

Toxic megacolondilatation WITH severe colitis + systemic toxicity (UC/C. difficile)

Paralytic ileussmall AND large bowel quiet post-operatively; less focal massive caecal dilatation

Investigations

AXR/CT showing colonic dilatation without a mechanical lesion; CT or water-soluble contrast enema to EXCLUDE mechanical obstruction; U&E/Ca/Mg/PO4 (correct); exclude toxic megacolon (no colitis/systemic toxicity of severe colitis).

Management

Conservative (correct electrolytes, stop opioids, decompress) → IV neostigmine if failing; surgery if perforation

1EXCLUDE mechanical obstruction (CT). Correct electrolytes, stop opioids/anticholinergics, NG/flatus tube, mobilise; serial AXR and caecal diameter for 24–72 h if caecum <12 cm and patient stable.Gate: If the caecum is >12 cm, rising, or there is no resolution within 24–72 h → IV neostigmine under continuous cardiac monitoring (atropine ready); colonoscopic decompression if neostigmine fails or is contraindicated.
2Surgery (caecostomy or colectomy) for perforation or colonic ischaemia.

Conservative bundle — NBM, NG/flatus tube, correct K/Mg/Ca, STOP opioids/anticholinergics, mobilise, serial caecal measurement — first-line if caecum <12 cm and stable

IV neostigmine — if conservative therapy fails — give under continuous cardiac monitoring (bradycardia/bronchospasm; atropine to hand); 60–90% decompress

Colonoscopic decompression — if neostigmine contraindicated/fails

Surgery (caecostomy/colectomy) — perforation or ischaemia

Key points

Massive colonic dilatation with NO mechanical cause and NO colitis, in a frail/post-op patient on opioids = Ogilvie's → correct electrolytes + stop opioids; neostigmine (cardiac-monitored) decompresses; perforation risk climbs once the caecum exceeds ~12 cm.

Monitor & prognosis

Serial caecal diameter; continuous cardiac monitoring during neostigmine.

Good with timely decompression; high mortality if caecal perforation occurs.

Source: ASCRS; StatPearls