The purpose of this study is to investigate the incidence and risk factors associated with vesicoureteral reflux (VUR) in patients with ulcerative bladder pain syndrome/Interstitial Cystitis (BPS/IC).

We evaluated 211 patients with BPS/IC who underwent cystoscopy and confirmed the presence of Hunner’s ulcer from May 2011 to July 2017 retrospectively. Among these patients, 113 patients whose functional bladder capacity was 300cc or less according to the voiding diary were included in this study. All patients were evaluated by voiding cystourethrography (VCUG) to check for the presence of bladder destruction and VUR. Patients were classified into two groups according to presence of VUR and the risk factors for VUR include the locations and numbers of Hunner’s ulcer, functional bladder capacity, maximal flow rate (Qmax), post voiding residual urine volume (PVR), the degrees and duration of the pain were assessed using univariate and multivariate logistic regression analysis.

Of 113 patients, the mean bladder capacity was 205.3±77.9cc and 28 patients were confirmed VUR by VCUG (28/113, 24.8%). The maximum functional bladder capacity of patients with VUR was significant lower than patients without VUR (156.8±72.8cc vs. 221.2±73.2cc, p<0.05) and it affects the presence of VUR in univariate analysis. In addition to functional bladder capacity, the location of Hunner’s ulcer especially in peri-ureteral location was also significant risk factor whereas other parameters such as numbers of ulcer, degrees of pain, duration of symptoms, Qmax and PVR did not affect the presence of VUR in ulcerative BPS/IC. In multivariate logistic regression analysis, the peri-ureterally location of Hunner’s ulcer was the only independent risk factor for presence of VUR in ulcerative BPS/IC (OR, 3.506; 95% CI, 2.380 to 5.164; p<0.001) (Fig. 1).

A well-known major complication of chronic IC is VUR. The currently understood pathophysiology of VUR is that if appropriate measures are not undertaken in patients with severe IC, serious bladder contraction develops, resulting in a decreased bladder capacity and eventual VUR. Reflux of urine exposes the renal parenchyma to higher than-normal hydrostatic pressures. In addition, ascending infection from the bladder is a cause of kidney infection. Untreated and prolonged urinary tract infection can eventually lead to renal scarring, also known as reflux nephropathy. Renal scarring, which is characterized by permanent damage to the renal parenchyma, can lead to high blood pressure and renal failure, for which dialysis or kidney transplantation may be necessary.
However, in clinical practice, not all patients with IC and a decreased bladder capacity have VUR. Moreover, the severity of the decreased bladder capacity does not necessarily correlate with the severity of VUR. Thus, we speculated that the development of VUR in patients with IC must be due to a variety of interrelated factors. In this study, we assumed that commonly found Hunner lesions, when located close enough, may cause ureteral orifice malfunction, thereby acting as another pathologic factor leading to ipsilateral VUR.
In our study, the peri-ureterally location of Hunner's ulcer had major responsibility to the presence of VUR. It showed that among the various factors that may affect the bladder dysfunction in patients with BPS/IC, the presence and location of Hunner's ulcer is one of the most important factor that urologists have to consider in the management of the patients with BPS/IC.

VUR is not an uncommon complication in patients with IC. In addition,the development of VUR in patients with IC is probably due to multiple variable factors but the presence of periureterally located Hunner lesions is likely to be an important factor in the development of ipsilateral VUR.
The incidence of VUR in patients with ulcerative BPS/IC is relatively high and the urologist has to consider the presence of VUR in the management of the patients with ulcerative BPS/IC especially when confirmed peri-uretrally located Hunner’s ulcer.