Polypoid cystitis. A catheter associated lesion of the human bladder

Histopathological examination of the urinary bladders of 63 patients dying in a geriatric clinic was performed. In 40 of 51 patients who had been treated with a urinary catheter, histological changes of polypoid cystitis were found. In 34 of the bladders the lesion engaged the posterior wall which corresponds to the localization of the tip of the catheter. The frequency of polypoid cystitis increased with increasing time of catheter treatment and reached its peak by 3 months. After that time the frequency was relatively constant. The frequency of polypoid cystitis seemed not to be influenced by bacterial urinary tract infection. Urothelial atypia was not seen after catheter treatment.