The plain abdominal film accurately estimates extent of active ulcerative colitis.

The aim of our study was to establish whether plain abdominal film can accurately assess the extent of active ulcerative colitis. Ninety-seven ulcerative colitis patients were studied, in whom the extent of the macroscopic lesion was established either by colonoscopy (n = 75) or by resection (n = 22). Of these, 42 had proctosigmoiditis, 12 left-sided colitis, 12 subtotal colitis, and 31 total colitis. Nine well-tested features were used for the radiological classification of lesion extent. The radiologists were not given any clinical information. Seventy-eight patients (80.4%) were correctly classified by plain abdominal film (r = 0.86); the best concordance was achieved for proctosigmoiditis and total colitis (80.9 and 90.3%, respectively). In total colitis the most reliable radiological features were "irregularity of the mucosal edge" and "increased thickness of the colon wall, " which were present in 74.2 and 67.7%, respectively, of the correctly classified patients. The fourfold combination of these two features with "loss of haustral clefts" and "empty right colon" was present only in patients with total colitis, and at least one of these features was present in all but one of them. Conversely, all nine abnormalities were absent in 73.8% of patients with proctosigmoiditis. In conclusion, plain abdominal film is a reliable tool for judging the extent of lesion in active ulcerative colitis. It seems particularly accurate in total colitis, where, in the acute phases, it is most important to avoid invasive examinations.