A hugely dilated loop of colon with the other colon collapsed: which loop, where it points and whether there is a whirl at its base decide sigmoid versus caecal volvulus — and ischaemia or perforation decides surgery versus endoscopic decompression.
Orient first
- Sigmoid volvulus: elderly, constipated; the loop rises from the pelvis toward the right upper quadrant (coffee-bean), with loss of haustra.
- Caecal volvulus: younger; the dilated caecum lies in the left upper quadrant or mid-abdomen, with small bowel dilated and the distal colon empty.
- Caecal bascule is a fold without axial twist — treated like caecal volvulus.
Acquire the study
- Supine abdominal radiograph including the diaphragm and pelvis.
The manoeuvre
- Identify the dilated loop: haustra-less inverted U from the pelvis (sigmoid) vs a single dilated haustrated loop in the left upper quadrant (caecum).
- Measure the transverse diameter in cm: caecum > 9 cm or colon > 6 cm is dilated (verify local thresholds); rising caecal diameter predicts perforation.
- Sigmoid: coffee-bean sign, apex under the left hemidiaphragm, the loop overlaps the liver shadow.
What confirms it
- A dilated closed loop of sigmoid or caecum with a whirl or beak at its base and a collapsed distal colon.
What licenses you to exclude it
- Gas and stool reaching the rectum with no transition point and no whirl excludes volvulus — consider pseudo-obstruction.
The classic misread
- Calling pseudo-obstruction a volvulus — gas extends to the rectum and there is no apex or whirl.