Overactive bladder (OAB) symptoms is common lower urinary tract symptoms (LUTS) in women. However, all women complaining storage symptoms are not OAB and some of them showed bladder outlet obstruction (BOO) by urodynamic study (UDS) and their OAB symptoms can be reduced by medication with alpha blocker. Therefore, we evaluated urodynamic characteristics of women whose predominant LUTS was OAB symptoms and diagnosed as female BOO by UDS. In addition, we tried to find urodynamic characteristics of BOO in women presenting OAB symptoms compared with women with no LUTS and SUI.

One hundred eight women whose dominant LUTS was storage symptoms and diagnosed with a female BOO by UDS were included into this retrospective study. We compared urodynamic findings of women with BOO and women with no LUTS and stress urinary incontinence (SUI) to identify characteristics of BOO in women. Women with SUI included in this study were diagnosed by clinical history, physical examination, and urodynamic study. Thirty-four women without LUTS and received UDS were included as control group. The diagnostic criteria of female BOO were as follows: maximum flow rate (Qmax) < 15 ml/s, combined with detrusor pressure at maximum flow rate (PdetQmax) > 20 cmH2O in pressure flow study.

Qmax and postvoid residual volume (PVR) were significantly different in women without LUTS, and SUI. Maximum cystometric capacity (MCC), PdetQmax, maximum urethral closing pressure (MUCP) were significantly different among 3 groups. In particular, MUCP of women without LUTS, BOO and SUI (76.2±24.0, 105.0±39.2, and 30.2±7.3 cmH2O, respectively) was significantly different.  Significantly lower Qmax and increased postvoid residual volume of uroflowmetry were observed in women with BOO compared with women without LUTS. MCC of women with BOO was significantly lower. Moreover, significantly lower Qmax was noted in women with BOO. PdetQmax, and MUCP were significantly higher in women with BOO. Significantly lower Qmax and increased PVR were observed in women with BOO compared with women with SUI. MCC of women with BOO was significantly lower. Moreover, significantly lower Qmax was noted in women with BOO. PdetQmax, and MUCP were significantly higher in women with BOO.  Thirty eight (35.2 %) of 108 women with BOO showed detrusor overactivity (DO). We found that 19 (17.6%) of 108 women with BOO  also showed bladder pain syndrome (BPS).  Women with BOO and BPS showed significantly decreased MCC compared with women with BOO. PdetQmax and MUCP of women with BOO were significantly higher compared with women with BOO and BPS.

Different urodynamic findings were observed between women with BOO and SUI. Women with BOO showed decreased Qmax, MCC and increased PVR compared with women without LUTS and SUI. In particular, MUCP of women with BOO was significantly higher compared with women without LUTS and SUI. MUCP of women with SUI was significantly lower compared with women without LUTS and BOO. Sub analysis of women with BOO showed that DO was observed about 35% of women with BOO. Thus, DO induce by BOO contributes to OAB symptoms in Women with BOO. In addition, we noted that  BPS can be existed in women whose predominant LUTS was OAB symptoms and diagnosed as BOO. Moreover, women with BOO and BPS showed different urodynamic characteristics compared with women with BOO only.

Higher MUCP was characteristic finding in women presenting OAB symptoms and BOO compared with women without LUTS and SUI. Moreover, decreased MCC due to BOO might cause OAB symptoms such as frequency and urgency. Moreover, DO noted in women with BOO contribute to induce OAB symptoms. In this study, we observed that BPS can be coexisted in the women whose predominant LUTS was OAB symptoms and diagnosed as BOO. From these results, we assume that  female BOO is very complex disease with various symptoms and underlying cause.