Aims of Study:
To determine the most reliable method of demonstrating and quantifying stress urinary incontinence (SUI) by prospectively studying variations in abdominal leak point pressure (ALPP) and the objective demonstration of SUI as determined by cough or Valsalva manoeuvre.

Methods:
34 female and 16 male patients, mean age 55y., with urinary incontinence (16 SUI, 30 mixed/urge incontinence and 4 neuropathic bladders) underwent multichannel videourodynamic study (Urovision Janus; LifeTech Inc.). At 250 cc. fill volume, each patient generated 3 consecutive coughs (C) and Valsalva manoeuvres (V) at maximum effort. Abdominal pressure and ALPP were compared with regard to pressure generated, induction of urinary leak and pressure variation. Statistical analysis was by paired Student's t-test and analysis of variance.

Results:
Of 314 provocative manoeuvres, 92(29%) produced leak in 21(42%) patients. Pressures were significantly higher with C in 41(82%) patients and 270(86%) manoeuvres. Leak was demonstrated in 21 of 26(81%) patients complaining of SUI; 19(90%) by C, 14(67%) by V and 11(52%) by both. Failure to perform both manoeuvres or to repeat manoeuvres would have missed SUI in 8(38%) and 3(14%) patients respectively. In 16 patients with type 3 SUI, C underestimated the severity of outlet incompetence in 13(81%). In 5 patients with type 2 SUI, V failed to produce leak in 4(80%). Pressure variation was similar for both manoeuvres, although V pressure had a greater tendency to decline with repetition (21% vs 7%; p = 0.02).

Conclusions:
For objectively demonstrating SUI, C is superior to V. V underdiagnoses type 2 SUI and C underdiagnoses type 3. The results support the use of both manoeuvres to quantify ALPP and the use of repetitive manoeuvres further enhances diagnosis.