Caption

Healthy rectum, coloured double contrast barium X- ray. The rectum (black, lower centre) is the last part of the digestive system, responsible for storing faeces before they are excreted through the anus (bottom centre). The last part of the colon is seen above the rectum. A double contrast barium X-ray uses a radio-opaque barium solution introduced through the anus, then dilates the intestinal tract with air. This is a useful diagnostic technique for identifying some disorders of the bowel.