[Imaging diagnosis in pseudomembranous colitis]

Pseudomembranous colitis (PC) is a dangerous inflammatory disease which arises as a complication of systemic antibiotic therapy. The colon is the preferred localization of PC, which is caused by the alteration in the bacterial population of the bowel which favors the growth and activation of several germ types--e.g., the Clostridium difficile, whose toxins can damage the colonic mucosa deeply. Later, the condition may affect extramucosal structures thus causing an actual parietal alteration. Clinically, PC patients present with diarrhea, abdominal pain, onset or worsening of fever, impairement of the main body functions. The colonic mucosa appears macroscopically edematous and is covered with yellowish plaques, called "pseudomembranes", which adhere strictly to the mucosa. Pseudomembranes are made by fibrin, mucus, leucocytes and epithelial remnants. The diagnosis is made on the basis of laboratory tests--i.e. the demonstration of Clostridium difficile or its toxins in the feces. Endoscopy is the examination of choice when PC is suspected because it can demonstrate the typical mucosal alterations directly. In this paper the main etiologic, pathologic and clinical features of PC are presented and the role of diagnostic imaging examinations is discussed, not only in demonstrating the typical lesions but also in the spatial evaluation of the condition and in its follow-up.