Diarrhoea and pseudomembranous colitis after gastrointestinal operations. A prospective study

241 patients who had gastrointestinal operations were studied prospectively. Postoperative diarrhoea occurred in 58 patients (24%) and was significantly more common after exposure to antibiotics. 9 patients (4%) had high titres of a neutralisable faecal toxin characteristic of pseudomembranous colitis. Toxigenic Clostridium difficile strains were isolated from the stools of all patients with neutralisable faecal toxin. If pseudomembranous colitis is defined as the presence of neutralisable faecal toxin, then the diagnosis is often missed by sigmoidoscopy and rectal biopsy.