Introduction. The search for pathogenetic mechanisms of recurrence of urinary tract infection (UTI) is an important link in choosing a treatment method. Knowledge of the histopathological changes in the bladder wall will help to develop an evidence-based treatment.

Materials and methods. We enrolled 58 female patients with recurrent uncomplicated bacterial UTI. All of patients underwent video cystoscopy with a biopsy of the bladder wall using the "cold-cup" forceps method. Spearman correlation analysis was performed to assess the strength of association (correlation) between clinical data, the severity of changes on histological examination and the total score of the Pelvic Pain and Urgency/Frequency Patient Symptom Scale (PUF Scale). Differences at p < 0.05 were considered statistically significant.

Results. To standardize the results, a scoring scale was developed and used in this study to describe histopathological changes of urinary bladder biopsy specimens. Urothelial status, percent of mucosa denuded of urothelium, severity of chronic inflammation and of lamina propria sclerosis were studied. Hystopathological analysis confirmed the presence of chronic inflammation in all 58 patients (100%), accompanied by sclerosis in 70% of cases and violation of the integrity of the urothelium in 91% of cases.

Conclusion. Our data indicate that chronic recurrent bacterial infections of the urinary tract are associated with a violation of the integrity of the transitional cell epithelium of the bladder wall. Insufficiency of urothelial function can be caused by UTI, and conversely, deficiency of the urothelium of the bladder wall can be a risk factor for chronic UTI.