Early recognition of toxic megacolon.

Increased amounts of small bowel gas are a frequent finding on plain abdominal films in toxic megacolon (TMC), but they may also be found in patients with severe colitis. We studied 69 consecutive patients with severe ulcerative colitis to evaluate whether an increased gas content of the small intestine may identify patients prone to TMC. The intestinal gas was measured on plain abdominal films by means of a planimeter. On the basis of gas values, 38 patients showed a normal and 31 an increased amount of small intestinal gas. The outcome of the disease (complications, need for surgery, and mortality rate) and 18 clinical and hematochemical findings were compared in the two groups. Of the 31 patients with increased gas, seven developed TMC, whereas this complication was not observed in the 38 patients with normal gas. The only other different features between the two groups were blood pH and base excess, which were significantly higher in the patients with increased small bowel gas content. We therefore suggest that persistent abnormal gaseous distension of the small bowel, together with severe metabolic alkalosis, characterizes a subgroup of patients with severe colitis at high risk for the development of TMC. The strict surveillance of these patients led to early recognition of seven cases of TMC and prompt institution of aggressive medical treatment. Since all these patients survived, the early detection of TMC may improve prognosis.