Ulcerative colitis is a type of inflammatory bowel disease (IBD) that characteristically involves the large bowel. Ulcerative colitis involves only the mucosa, with the formation of crypt abscesses and a coexisting depletion of goblet cell mucin. In severe cases, the submucosa can be involved, and in some cases, the deeper muscular layers of the colonic wall can also be affected.

Barium enema findings in ulcerative colitis -
The findings on a barium enema examination vary with the stage and severity of disease. The radiographic changes may involve the whole colon, but when the disease is segmental, the left colon is usually involved. Rectal sparing is rare and thought to occur in 5% of patients. Skip lesions are unusual. The colon may appear narrow; this is often associated with incomplete filling due to colonic spasm and irritability.

The earliest mucosal changes are best depicted on a good-quality double-contrast barium enema study. Before ulcers appear, mucosal edema produces a fine, granular appearance when the radiographs are seen en face. When ulcers first appear, the mucosa may have a fine, stippled appearance when seen en face. When mucosal ulcers become established and confluent, the mucosa is replaced by granulation tissue and double-contrast enema study reveals a characteristic, coarsely granular appearance.

In the acute and subacute phases of the disease, the ulcers may acquire variety of shapes: Collar-button ulcers occur with undermining of the ulcers, and double-tracking ulcers are longitudinally orientated and sometimes several centimeters long.

Symmetric thickening of haustral folds may produce the appearance of thumbprinting. Pseudopolyps are a consequence of severe mucosal disease and appear as multiple filling defects of varying sizes. These may develop rapidly and tend to persist, even when the ulcerative colitis is quiescent. Occasionally, mucosal bridges are formed between pseudopolyps, which may be radiologically demonstrable.

With increased severity and duration of disease, the involved colon may become narrow, shortened, and loose in terms of its normal redundancy and haustral pattern. On lateral projections, rectal narrowing is easily demonstrated as increased retrorectal space. When the entire colon is involved, changes in the terminal ileum may be seen (backwater ileitis); this involves 4-25 cm of the terminal ileum. The ileocecal valve appears patulous. The mucosa is granular and usually associated with absent peristalsis.

Benign strictures usually occur (1-11%) in patients with long-standing disease and are predominantly found in the left colon. Carcinomas that complicate ulcerative colitis are usually annular and may be difficult to differentiate from benign strictures. Often, however, malignant strictures are eccentric, with nodular narrowing and shouldered edges. Multiple carcinomas are not rare in the setting of ulcerative colitis.