Synopsis
Differentiate mechanical large-bowel obstruction from acute colonic pseudo-obstruction, detect threatened caecum or bowel early, and sequence resuscitation, decompression, stenting or surgery safely.
- Mechanical large-bowel obstruction has a physical transition point, most often colorectal cancer, diverticular stricture or volvulus; pseudo-obstruction has diffuse functional dilatation without that lesion.
- Progressive distension, colicky pain, obstipation and later faeculent vomiting are typical, but partial obstruction may still pass liquid stool or flatus.
- A competent ileocaecal valve can create a closed loop between an obstructing distal lesion and the valve, rapidly increasing caecal tension and perforation risk.
Key red flags
Progressive abdominal distension, colicky pain and obstipation with a CT transition at an annular mass or benign stricture supports mechanical large-bowel obstruction and needs urgent colorectal planning.
Investigation priorities
Locate a transition point, identify tumour, stricture or twist, distinguish pseudo-obstruction and assess bowel viability and perforation.
Management branches
Distension, colic and obstipation suggest an occluding colonic lesion.
- Keep fasting, obtain venous access, correct fluid and electrolyte deficits, provide analgesia and antiemetic treatment, and insert a nasogastric tube when vomiting or proximal dilatation warrants it.
- Perform rectal and hernia examination, send urgent bloods and obtain contrast CT with direct radiology discussion about transition, caecal risk, metastases and viability.
Key medicines
Intravenous crystalloid and electrolytesGive reassessed isotonic fluid and replace potassium or magnesium through the current hospital protocol, accounting for kidney function, cardiac reserve and measured deficits.
NeostigmineUse only the specialist-approved intravenous regimen in a monitored area after CT excludes mechanical obstruction and the team confirms viable bowel and appropriate resuscitation support.