Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic disease requiring long-term repeated treatment. Although our previous study has demonstrated the value of urodynamic study (UDS) on IC/BPS [1], the role of UDS on IC/BPS remained controversial and little was known about the long-term bladder storage and voiding functional changes of UDS findings in IC/BPS patients. This study investigated the changes of video UDS (VUDS) parameters in a cohort of IC/BPS women underwent long-term treatment and follow-up in a tertiary medical center. The clinical factors that might affect the changes of UDS parameters were also evaluated.

IC/BPS women who have been followed up for two years or more and had at least two records of VUDS with an interval of one year or more were enrolled. VUDS was performed at baseline and in case the treatment outcome was not satisfied or other pathologies were suspected. The changes of VUDS parameters including first sensation of filling (FSF), first desire to void (FD), strong desire to void (SD), maximum flow rate (Qmax), detrusor pressure at Qmax (Pdet), voided volume (Vol), post-void residual volume (PVR), cystometric bladder capacity (CBC) and bladder compliance were analysed between baseline and the latest VUDS and were compared between patient groups stratified with different age (<55 vs. ≥55), baseline CBC (<250 vs. ≥250 ml), PVR (<100 vs. ≥100 ml), result of potassium sensitivity test (PST) (negative vs. positive), IC phenotype (ulcer vs. non-ulcer), cystoscopic maximal bladder capacity (MBC) (<600 vs. ≥600 ml) and degree of glomerulations (≤1 vs. =2 vs. >2).

A total of 212 female IC/BPS patients (mean age, 60.8±13.3; range 24~95) were included in this study. The mean duration of history of IC/BPS was 16.2±10.4 (2-61) years. The mean interval between the baseline and the latest VUDS was 6.4±4.7 (1~20) years. After long-term follow-up, most of the VUDS parameters did not change except the mean FSF, FD and PVR increased significantly at follow-up (Table 1). Patients with a baseline CBC<250 mL had significantly larger increases in the volumes at FD, SD, Vol and CBC than those with a CBC≥250 mL (Table 2). Subjects with a baseline PVR ≥100 mL had significantly increased Qmax and Vol, and decreased PVR while subjects with a baseline PVR<100 mL had significantly decreased Qmax and Vol, and increased PVR. Those with a baseline positive PST had a significantly smaller increase in FSF and FD. Women with ulcer type IC/BPS had a significantly larger increase in PVR. Nevertheless, there was no significant difference in the changes of all the VUDS parameters between patients stratified with different age, cystoscopic MBC and degree of glomerulations.

Our results demonstrated FSF and FD but not Vol or CBC increased significantly at follow-up, indicating that there was a little improvement in the urothelial function after treatment, yet the overall storage function in women with IC/BPS did not alter after long-term treatment and follow-up. However, the storage function in patients with a baseline CBC<250 mL did improve according to significantly larger increases in volumes at FD, SD, Vol and CBC. For women with a baseline PVR ≥100 mL, there is low risk of receiving long-term treatment (having significantly increased Qmax and Vol, and decreased PVR). Patients with a positive PST at baseline may have more severe urothelial dysfunction which responded to treatment and thus had a significantly smaller increase in FSF and FD. A larger increase of PVR in women with ulcer type IC/BPS may be attributed to augmentation enterocystoplasty performed in more than half of the patients (12/21).

After long-term follow-up, the overall storage function did not change in women with IC/BPS. However, the storage VUDS parameters could be affected by clinical factors such as patients with a baseline CBC < 250 mL and with a positive PST. Even in subjects with a large baseline PVR (≥100 mL), there was low risk of receiving long-term treatment.

Kuo YC, Kuo HC. Videourodynamic characteristics of interstitial cystitis/bladder pain syndrome-The role of bladder outlet dysfunction in the pathophysiology. Neurourol Urodyn 2018; 37:1971-7.