AbstractAimsObstructive symptoms such as slow stream, dribbling and straining are often reported by painful bladder syndrome and interstitial cystitis (PBS/IC) patients. Our hypothesis was that some patients with PBS/IC have an associated measurable bladder outlet obstruction (BOO) secondary to dysfunctional voiding and that those patients with more severe PBS/IC are more likely to have BOO.MethodsThis is a retrospective chart review of female patients diagnosed with PBS/IC based on the NIDDK research definition. Charts were reviewed for clinical symptom severity, ulcer or non‐ulcer PBS/IC on cystoscopy, and pressure‐flow urodynamics (UDPF). Patients were excluded if they had a urinary infection at the time of urodynamics or did not meet study entry requirements. The cut‐off values of ≤12 ml/sec and ≥25 cm of water was used to define BOO.ResultsOf the 231 women: 38 had ulcer PBS/IC and 193 had non‐ulcer PBS/IC. MCC was 269 ml in non‐ulcer PBS/IC and 200 ml in ulcer PBS/IC (P = 0.006). One hundred eleven women (48%) met criteria for obstruction. MCC was 298 ml in the non‐obstructed group and 214 ml in the obstructed group (P < 0.0001). The maximum flow with non‐ulcer PBS/IC was 11.0 ml/sec and in ulcer PBS/IC 8.9 ml/sec (P = 0.04) Detrusor pressure at maximum flow was 33.3 cm H2O, in non‐ulcer, and 37.4 cm H2O in ulcer PBS/IC (P = 0.01).ConclusionsForty‐eight percent of our PBS/IC patients have BOO, and increasing severity of PBS/IC is associated with higher voiding pressure. Neurourol. Urodynam. 28:944–948, 2009. © 2009 Wiley‐Liss, Inc.