Pseudomembranous colitis: sonographic features.

The sonographic features of pseudomembranous colitis (PMC) are described in 13 patients and correlated with clinical, radiologic, and pathologic findings. At sonography, the wall of the entire colon was moderately to markedly thickened in all patients. The enlarged colon wall was most commonly shown as a wide band of heterogeneous medium echogenicity surrounded by a narrow hypoechoic layer. Pathologic correlations proved that the wide inner stratum represented severely edematous submucosa and mucosa, while the outer layer depicted the muscularis propria. Almost complete effacement of the lumen of the colon occurred secondary to the mural edema in 69% of the cases. The dearth of intraluminal gas combined with thickening of the colon wall and ascites facilitated excellent sonographic evaluation. The diagnosis of PMC is strongly suggested by the presence of these sonographic features in a patient with watery diarrhea and a history of antibiotic therapy.