Physiologic outcome measures for urinary incontinence.

Physiologic outcome measures are divided into 2 groups: (1) measures that visualize, quantify, and analyze the reasons for urine loss and (2) measures that assess the anatomy and neuromuscular function of continence-related structures. Few of the frequently used physiologic outcome measures have been rigorously tested. The evidence in support of their use derives mainly from case series information and expert opinion. Perineal pad testing is used to quantify urine leakage associated with stress incontinence. One-hour pad tests are commonly used for clinical trials and office visits; 24- and 48-hour tests are more reliable and reproducible. Urodynamic testing simultaneously assesses bladder and urethral function during bladder filling and emptying to help guide therapy and identify patients who are at risk for surgical failure. Testing usually includes (1) uroflowmetry, an assessment of voiding without catheters in place; (2) cystometry, which assesses bladder sensation, capacity, compliance, and inappropriate detrusor activity during filling; (3) urethral pressure profilometry, to gauge urethral closing pressures and pressure transmission ratios; (4) leak-point pressure, the minimum intra-abdominal pressure required to cause incontinence, which serves as a measure of urethral function; and (5) pressure flow studies, which diagnose obstruction by evaluating detrusor pressure and flow rate during voiding. The cotton swab test is used to assess bladder neck mobility after surgical interventions. Using the Pelvic Organ Prolapse Quantification system, researchers can describe pelvic support in a standardized, reproducible fashion. Applications of ultrasonography and magnetic resonance imaging in urogynecology are promising but remain in the investigational stages.