Uroflowmetry: its current clinical utility for women

Abstract

Uroflowmetry, the simple, non-invasive measurement of urine flow over time during micturition, has a long and interesting history, clear definitions, a clear purpose in screening for voiding difficulty and, most importantly, technical accuracy. Data interpretation is currently limiting its clinical utility, despite appropriate analysis being available in long-standing existing research. The main clinically important numerical parameters are the maximum and average urine flow rates and the voided volume. Urine flow rates are strongly dependent on voided volume. Reference to established (Liverpool) nomograms will most accurately correct for this dependency. Nomograms will also optimise the validation of uroflowmetry data and the accurate assessment of its normality, compared with fixed urine flow rates and "cutoffs" for voided volume. Abnormally slow urine flow (under the 10th centile Liverpool Nomograms) is the most clinically significant abnormality. Repeat uroflowmetry, concomitant post-void residual measurement and voiding cystometry studies are appropriate options for evaluating any abnormal uroflowmetry.

Dysfunctional urinary voiding in women with functional defecatory disorders

“…(7, 46) Since uroflow rates and residual urine volume relative to total bladder volume are dependent on voided volume, the Liverpool nomogram is useful for interpreting uroflowmetry, (47) particularly to identify false-positive findings in patients who void less than 150 mL. (48) As observed previously, (49, 50) a small proportion, (i.e., 23% in this study), of asymptomatic women have uroflow abnormalities. Therefore, the diagnosis of voiding dysfunction should be based on an integrated consideration of clinical features and uroflowmetry findings, supplemented as necessary by urodynamic studies.…”

Objective comparison of subtotal vs. total abdominal hysterectomy regarding pelvic organ prolapse and urinary incontinence: a randomized controlled trial with 14-year follow-up

“…2 shows an increase in Qmax with increasing voided volume for SAH (blue) and TAH (red). The black line indicates the 50th percentile of the Liverpool nomogram calculated using the formula for the female nomogram: Ln(Qmax) = 0.511 + 0.505 Â Ln(Voided volume) [22,23]. The best logarithmic fits for our two surgical groups (red and blue lines) are slightly lower than the Liverpool nomogram but within normal range and with very similar slopes.…”

Urodynamic Testing

“…Several studies have established maximum urine flow rates to be greater than 12 mL/s [13,16]. According to the most recent ICS guidelines, abnormally slow flow rates have been determined as under the tenth percentile of the Liverpool nomogram which takes into account the voided volume [17,18]. Abnormalities in the flow pattern or rate can be due to various pathologies.…”