Twisted colon. Coloured X-ray of the abdomen of a patient with a twisted colon (large intestine), a condition known as a volvulus. The twist has led to a bloated air pocket forming behind it (black, top left). The soft tissue of the intestines are not clearly seen on the X-ray. Such a volvulus can lead to a partial or complete obstruction of the intestine, and may reduce the blood supply to the intestine, causing tissue death. It may untwist spontaneously or by external manipulation, but surgical treatment is usually required. The colon, which runs around the abdomen, lies towards the end of the digestive tract. The backbone (red & yellow, down centre) ends at the pelvis (bottom).