A critical appraisal of the methods of measuring leak-point pressures in women with stress incontinence.

OBJECTIVE: To determine whether leak-point pressures can be measured using an intravaginal catheter, and to assess whether leak-point pressures are affected by the provocation method, bladder volume, and the presence of a transurethral-intravesicle catheter.
METHODS: Thirty women with genuine stress incontinence had leak-point pressure studies performed, using both cough and Valsalva maneuvers at specific bladder volumes. Intravaginal pressure measurements were compared with intravesicle pressure measurements. The effect of an 8-Fr transurethral-intravesicle catheter on leak-point pressures was also assessed.
RESULTS: Leak-point pressures were demonstrated in all 30 patients by cough and/or Valsalva maneuver. There was no significant difference between intravesicle and intravaginal pressure measurements. Subjects who demonstrated leak-point pressures by both cough and Valsalva maneuver had significantly higher cough leak-point pressures at all bladder capacities. Seventeen women with measurable Valsalva leak-point pressures at 150 mL bladder capacity had significantly lower pressures at 300 mL, and 15 women had significantly lower leak-point pressures at 400 mL or more. Valsalva maneuver and cough leak-point pressures decreased significantly when the 8-Fr transurethral-intravesicle catheter was removed and the pressures were measured using only an intravaginal catheter.
CONCLUSION: Bladder volume, provocation method, and the presence of a transurethral-intravesicle catheter affect leak-point pressure measurements. Further standardization of leak-point pressure measurement technique is necessary before determining the clinical applicability of these tests.