Supine empty stress test as a predictor of low valsalva leak point pressure.

Our objective was to determine whether a positive supine empty stress test is predictive of a low Valsalva leak point pressure (< or =60 cm of water). Evaluation was carried out on 179 patients with a history of genuine stress incontinence confirmed with urodynamic testing. All patients had a supine stress test performed after voiding. Residual urine determinations were all <100 cc. A vesical Valsalva leak point pressure determination (cough and strain) was performed during multichannel urodynamics with 150 cc in the bladder. Urethral profilometry was performed at maximum capacity. There was a statistically significant relationship between a low leak point pressure and a positive supine empty stress test (P < 0.000). The supine empty stress test had a sensitivity of 79% and a specificity of 62.5% for the detection of a low leak point pressure. The negative predictive value was high at 90%. For the age group 50 years and younger the negative predictive value was 95%. However, there was no significant relationship between a positive supine empty stress test and a low maximal urethral closure pressure. We conclude that the supine empty stress test is a useful screening test for a low leak point pressure but not a low urethral closure pressure. Its high negative predictive value is useful in excluding the presence of a low leak point pressure and may help the clinician to determine which patients with genuine stress incontinence need further assessment of the dynamic function of the urethral sphincter.