Uroflowmetry provides a quantitative assessment of several voiding parameters and a graphical curve pattern, with time on the x-axis and flow rate on the y-axis. Curve patterns are interpreted inconsistently in the literature, but when done systematically, should include mention of continuous vs. intermittent flow, parabolic vs. left- or right-skewed shape, smooth vs. fluctuating pattern, and the presence vs. absence of an end-of-void dribble. The existing literature on uroflowmetry in females lacks accurate normative reference parameters and curve patterns. We hypothesized that uroflowmetry parameters and curve patterns in females would: (1) differ from established norms in males, given differences in anatomy and the impact of pregnancy and childbirth (in some females), and (2) vary with the presence of lower urinary tract symptoms (LUTS), overall bladder health, and age. The aims of this study were to describe objective uroflowmetry parameters and graphical curve patterns in females by LUTS, bladder health perception, and age.

The Validation of bladder health Instrument for Evaluation in Women (VIEW) study included volunteers from the community and clinical practice who completed validated LUTS and bladder health questionnaires and non-invasive uroflowmetry. Participants were classified into LUTS groups using validated questionnaires. Bladder health perception was categorized as low, medium, or high using the Global Bladder Health Scale. Participants were excluded if they were pregnant, had a recent UTI, used an indwelling or intermittent catheter, had NGB, or had a uroflowmetry voided volume <50 mL. Uroflowmetry was performed in accordance with Good Urodynamic Practices and interpreted using ICS standardized terminology.  Quantitative uroflowmetry parameters (maximum urine flow rate [Qmax]; average urine flow rate [Qave]; voided volume; flow time; total voiding time; time to Qmax) were extracted from printed reports after confirmation of accuracy. Graphical curve patterns (continuous vs. intermittent flow; parabolic vs. left- or right-skewed shape; smooth vs. fluctuating pattern; +/- end-of-void dribble) were coded independently by two experts in uroflowmetry (MG, ALS).  Descriptive statistics were used to summarize data.

Normative uroflowmetry parameters in participants who denied LUTS (n=22; Table 1) included Qmax 36.9 mL/sec, Qave 18.8 mL/s, voided volume 368.5 mL, flow time 22.3 sec, total voiding time 28.8 sec, and time to peak flow 6.2 sec. Normative curve patterns in women without LUTS were primarily continuous flow, parabolic shape, and smooth uroflow patterns, with or without end-of-void dribble (Figure 1a.).  In all 285 female participants, older age was associated with lower Qmax and Qave, a right-skewed uroflowmetry shape (p<0.01), and end-of-void dribbling (p<0.01; Table 2). Qmax and Qave were also 10 points lower in participants with storage LUTS (Qmax 26.8 vs. 36.9 mL/s, Qave 13.7 vs. 18.8 mL/s; p<0.05) and both voiding and storage LUTS (Qmax 26.3 vs. 36.9 mL/s, Qave 12.6 vs. 18.8 mL/s; p<0.05) compared to participants without LUTS. Participants with both voiding and storage LUTS were more likely to have an interrupted flow pattern (p<0.01) and a right-skewed uroflowmetry shape (p<0.06).  Poorer bladder health was associated with interrupted flow pattern, right-skewed shape, and more end-of-void dribbling (p<0.05). A variety of curve patterns from women with LUTS were observed (Figure 1, b-e).

The idealized, continuous, parabolic, and smooth uroflowmetry curve patterns were more common among female participants without LUTS and with better bladder health. Interrupted flow patterns, right-skewed shape, and end-of-void dribbling were more common in older female participants and those with poor bladder health.

Quantitative uroflowmetry parameters and graphical curve patterns varied in female volunteers based on age, the presence of subjective voiding and storage LUTS, and perception of bladder health.