Background: Electron microscopy (EM) characteristics of the urothelium in interstitial cystitis/bladder pain syndrome (IC/BPS) and their association with clinical condition are unclear.
Methods: Ten IC/BPS patients who were admitted for hydrodistention and 5 patients with stress urinary incontinence (control patients) were enrolled. All patients provided detailed clinical histories and underwent urodynamic studies. Cystoscopic bladder biopsies were obtained and processed for transmission EM (TEM) and scanning EM (SEM). The severity of the urothelium findings was graded on a 4-point scale (0: none, 1: mild, 2: moderate, and 3: severe). The EM findings between IC/BPS and control patients were compared; the results were analyzed using the chi-square test.
Results: Compared with the urothelium of control patients, the urothelium of IC/BPS patients had more severe defects of the urothelial cell layers and integrity of umbrella cells in TEM (p = 0.045 and 0.01, respectively). In SEM, umbrella cell pleomorphism increased and microplicae of the cell membrane decreased in the IC/BPS group, and both were more severe than in the control group (p = 0.022 and 0.007, respectively). The patients with moderate to severe defects of umbrella cell integrity had more severe bladder pain and smaller maximal bladder capacity (MBC) (both p = 0.010). Patients with moderate to severe defects in microplicae of the cell membrane had smaller cystometric bladder capacity and MBC (p = 0.037 and 0.047, respectively).
Conclusions: The results revealed significant urothelium defects in IC/BPS, especially in the umbrella cells. Defects of umbrella cells may play an important role in the pathogenesis of IC/BPS.