The subject of the investigation is to evaluate the contribution of MR examination in the diagnosis of postoperative conditions of the rectum. Within two years MR examinations were made in 19 patients after different operations of the rectum (abdominoperineal amputation of the rectum, resection of the rectosigmoid, anterior resection of the rectum, condition after total proctocolecto- my and after drainage of abscesses and fistulas in the rectal region). MR examination made according to the protocol recommended by the authors revealed 4 relapses of a tumour, 5 cicatrical infiltrates at the site of the surgical operation, 2 abscesses with fistulas and an obscure finding of infiltration reaching as far as the sacral bone and skeleton. In 6 patients the authors did not reveal signs of relapse nor complications. By postoperative biopsy or follow-up of the clinical finding 14 diagnoses were concordant, two discordant findings were proved and 3 cases were evaluated as not confirmed. The authors describe the causes of disagreement (2 false positive findings, where the cicatrical infiltration was evaluated as tumourous). The authors discuss the problemof aptness to use MRin the diagnosis of postoperative conditions of the rectumas compared with other imaging methods and the causes of falsely negative and positive findings. They demon- strate the indications for MR examination of the pelvis in the diagnosis of periproctal fistulas.

        Key words: MR examination in the diagnosis of postoperative conditions of the rectum - diagnosis of a recurrence of rectal tumours - differential diagnosis of a relapsed rectal tumour and postoperative fibrosis - diagnosis of periproctal and perianal fistulas by MR