Written & reviewed by: Kinase Medical Team · Last reviewed: 30 September 2026 · Editorial policy
Key features
- Coffee bean / bent inner tube sign: a large dilated gas-filled loop without haustra (closed-loop obstruction).
- The loop's convexity points to the right upper quadrant, with its lower end in the pelvis.
- Water-soluble contrast enema shows tapering at the twist — the bird's beak sign.
- The most common form of intestinal volvulus (about 60%), typically in the elderly with chronic constipation.
Differential diagnosis
| Condition | How to tell it apart |
|---|---|
| Caecal or transverse colon volvulus | Schwartz notes sigmoid volvulus can usually be told apart on plain X-ray by the shape and position of the loop. |
| Small-bowel obstruction | Multiple air–fluid levels without significant colonic distension. |
How it appears in NEET PG
One of the most recognisable plain-film signs; usually shown with an elderly, constipated patient with massive distension, asking for the sign or the diagnosis.
Frequently asked questions
What is the coffee bean sign?
The plain-film appearance of a massively distended, closed sigmoid loop whose two limbs touch in the middle, giving the shape of a coffee bean.
What does a contrast enema show in sigmoid volvulus?
Smooth tapering of the contrast column at the point of twist, called the bird's beak sign.
Who typically gets sigmoid volvulus?
Older people, especially those with chronic constipation or laxative use.
Sources
- Radiopaedia — Sigmoid volvulus
- Schwartz's Principles of Surgery (textbook)
- Harrison's Principles of Internal Medicine (textbook)
Keep practising
- NEET PG Radiology previous-year questions
- Pneumoperitoneum (Air Under the Diaphragm)
- Boot-Shaped Heart (Tetralogy of Fallot)
- Extradural (Epidural) Haematoma on CT
- All clinical images
For exam preparation and medical education only — not a substitute for clinical judgement, diagnosis or treatment of any patient.