Assessment of the malignant potential of cystoplasty.

The study group comprised 34 patients with either an ileal augmentation cystoplasty or a colonic substitution cystoplasty. The histological appearance of the intestinal segment, suture line, bladder remnant and bacterial colonisation of the urine and urinary nitrosamine levels were recorded. There was a high incidence of histological abnormalities, the more significant of which correlated with heavy mixed bacterial growth on urine culture and with high levels of urinary N-nitrosamines. This group of compounds is thought to act as carcinogens in both bladder and bowel under certain circumstances. It was concluded that patients undergoing lower urinary tract reconstruction using intestinal segments should be considered at risk of developing malignant change either in the intestinal segment or in the bladder remnant. Close long-term follow-up of these patients is essential.