Patients who have undergone implantation of ureters into the sigmoid colon (ureterosigmoidostomy) are known to be at high risk of developing cancer of the colon many years later. The operation is often performed in infancy for congenital abnormalities of the bladder, thus creating a long term surveillance problem.

Six of 34 patients (17.6 per cent) who had undergone ureterosigmoidostomy were found at a screening fibresigmoidoscopy to have adenomas of the left colon or severe dysplasia of the stoma, a mean interval of 22 years after their urinary diversion. Four other patients had previously had a sigmoid adenoma or cancer; thus, 29 per cent overall had developed colonic neoplasms, almost all closely related to their stomas. Another patient who, by error, was excluded from the surveillance, died of metastatic cancer of the sigmoid colon within the study period.

Regular surveillance by fibresigmoidoscopy of patients who have had urinary diversion affords the opportunity to detect and remove potentially malignant sigmoid lesions. In addition to its clinical importance, it allows a closer study of this unique model of colon carcinogenesis.