Leak-point pressure: clinical application of values at two different volumes.

A prospective analysis of 306 consecutive patients with genuine stress incontinence was performed to evaluate the clinical usefulness of additional leak-point pressure (LPP) determination at 200 ml. LPP values at both volumes were compared to maximal urethral closure pressure (MUCP) in an attempt to determine a critical cut-off value for the detection of a low MUCP (< or =20 cmH2O). A positive LPP at 150 ml was found in 157 patients. The mean LPP for patients with a low MUCP was 58.5 cmH2O compared to 71.6 for those with a normal MUCP, which was statistically significant (p = 0.01). The correlation coefficient between LPP and MUCP was 0.317. A negative LPP was found in 30% (24/79) of the total having a low MUCP. The addition of values for LPP at 200 ml resulted in an increase in the number who leaked to 191, a 50% increase in the detection rate of low MUCP and a statistically significant relationship between LPP < or =60 cmH2O and low MUCP. Various critical cut-off values for LPP demonstrated good specificity but poor sensitivity for the detection of a low MUCP. It was concluded that there was a statistically significant relationship between LPP and MUCP. Performing LPP at 200 ml provides additional clinically useful diagnostic information.