Reference Urodynamic Values for Stress Incontinent Women

Objective: To determine reference urodynamic values for preoperative urodynamic studies in women undergoing surgery for pure or predominant stress urinary incontinence (SUI). Materials and Methods: Six hundred fifty-five women with pure or predominant SUI were enrolled in a multicenter surgical trial and were randomized to undergo a Burch or autologous fascia sling procedure as part of the Urinary Incontinence Treatment Network (UITN) Stress Incontinence Surgical Treatment Efficacy Trial (SISTEr). Preoperative free uroflowmetry, filling cystometry, and pressure flow studies were performed in all women using a standardized research protocol and standardized urodynamic interpretation guidelines. We define the normal range of urodynamic values in this population as the values that encompass 95% of the results. Results: In 655 women undergoing filling cystometry in the standing position, baseline vesical and abdominal pressures were between 12 and 60 cm H₂O. The upper limit of detrusor pressure increase during bladder filling to maximum cystometric capacity was 16 cm H₂O. Ten percent of women who qualified for stress incontinence surgery with a positive cough stress test on physical exam did not demonstrate urodynamic stress incontinence (USI) and less than 10% of subjects in this study demonstrated detrusor overactivity. Conclusions: Results from a large cohort of women with SUI are now available for quantitative plausibility assessments or as reference values when interpreting urodynamic studies.