Uroflowmetry in Women with Urinary Incontinence and Pelvic Organ Prolapse

Objective: To characterize uroflowmetry parameters in women with pelvic organ prolapse (POP) and urinary incontinence (UI) and to assess the effects of clinical and urodynamic variables on these parameters.

Patients And Methods: The study comprised 655 consecutive women who presented with UI or POP and who had interpretable uroflowmetry values. Normal uroflowmetry values were defined as a maximum flow (Q(max)) > or = 15 mL/s, a mean flow (Q(mean)) > or = 10 mL/s, a post-void residual volume (PVR) < or = 100 mL and a continuous, single-peak waveform. Parametric and non-parametric analysis of variance and chi-square analysis were used to compare differences between diagnostic groups. Multiple linear regression models were developed to evaluate factors considered to influence uroflowmetry.

Results: Of the 655 patients, 471 (72%) had UI of whom 16% had pure detrusor instability (DI), 69% pure genuine stress incontinence (GSI) and 15% with both, and 184 (28%) had POP, 26% of whom also had DI. Of all patients, 72% had normal uroflowmetry patterns, 13% had multiple peaks and 15% had patterns with interrupted flow; 56% had completely normal uroflowmetry. There were significant differences in uroflowmetry values between the POP and UI groups, with the former having a lower Q(max) and Q(mean) (P < 0.001), larger PVRs (P < 0.001) and a lower percentage of totally normal uroflowmetry (33% and 64%, respectively, P < 0.001). Of patients with POP, 30% had a PVR > 100 mL. Because of the differences, the POP and UI groups were evaluated separately in the regression analysis. In both groups, the most important determinants of flow rate were the volume voided and pressure transmission ratio (PTR). However, when several factors (including age, voided volume, PTR and maximum detrusor pressure with flow and at Q(max)) were included in the model, they accounted for only 23-26% of the variability of flow in the patients with UI and 36-39% of the variability in patients with POP. The subsets of patients with pure DI in both the UI and POP groups had higher PVR volumes than the other subsets.

Conclusions: These results show that the positive correlation between flow rate and voided volume described in normal populations is also observed in women with UI and POP. However, most of the variability in urine flow was not attributable to factors such as age, voided volume and PTR, confirming the complexity of the micturition mechanism. Women with POP had more objective evidence of emptying-phase dysfunction than women with UI, although most emptied their bladders efficiently. Finally, the results suggest that women with DI exhibit dysfunction of both inhibitory and facilitory detrusor control.