The supine stress test: a simple method to detect intrinsic urethral sphincter dysfunction

A new clinical test for intrinsic urethral sphincter dysfunction is proposed and compared to abdominal leak point pressure determination by video urodynamics.

Patients were prospectively included in the study if they had stress urinary incontinence symptoms and were to undergo video urodynamic testing. Patients with urinary tract infection, cystocele, rectocele and vaginal vault prolapse were excluded from study. A supine stress test using cough and Valsalva's maneuvers was performed after bladder filling to 200 ml. with sterile normal saline solution by gravity. Efflux of the bladder solution from the meatus coinciding with the cough or Valsalva maneuver indicated a positive clinical test. A video urodynamic study, including abdominal leak point pressure, was performed. Intrinsic urethral sphincter dysfunction was diagnosed if abdominal leak point pressure was less than 100 cm. water. Test indexes were calculated based on the results of the supine stress test and the abdominal leak point pressure measurements.

Results were positive in 30 of 41 consecutive patients and negative in 11. Using abdominal leak point pressure measurement, the supine stress test had 93.5% sensitivity, 90.0% specificity, 96.7% positive predictive value and 81.8% negative predictive value for detecting intrinsic urethral sphincter dysfunction.

The supine stress test is easy, quick and inexpensive, and a positive test is a reliable predictor of intrinsic urethral sphincter dysfunction. A negative test is highly correlated with the absence of intrinsic urethral sphincter dysfunction during video urodynamic testing. This test is more reliable in diagnosing intrinsic urethral sphincter dysfunction than other nonurodynamic tests reported in the literature. The supine stress test can be a useful supplement to cotton swab testing for urethral hypermobility in determining the appropriate management for stress urinary incontinence.