Should Maximum Urethral Closure Pressure Be Measured on Prolapse Reduction?

Maximum urethral closure pressure (MUCP) is a measure of urethral quality and is associated with urodynamic stress incontinence (USI). A confounder of this relationship is pelvic organ prolapse (POP). We investigated the effect of prolapse reduction on MUCP and its association with USI.

We carried out an observational study using data sets of 1992 women seen at a tertiary urogynaecological centre in 2017-2024. All had undergone a questionnaire, POPQ examination and translabial ultrasound. MUCP was obtained after bladder emptying, at rest and during POP reduction. USI was rated mild, moderate, marked or severe. Associations between MUCP/MUCP on prolapse reduction and USI were tested using nominal regression. Nagelkerke R² were used to compare association strength.

Of 1992 women seen for urodynamic testing, 1737 had MUCP obtained at rest and POP reduction. Most complained of stress urinary incontinence (72.8%), and 7% reported splinting to void. On clinical examination, 82.8% had significant prolapse. USI was diagnosed in 61.9%, detrusor overactivity in 22.6% and voiding dysfunction in 31.9%. Mean MUCP was 39.1 cm H₂O at rest (standard deviation [SD] 18.2) and 33.9 (SD 17.6) on prolapse reduction (p < 0.001). This reduction was greater in women reporting splinting (p = 0.004) and weakly associated with Ba (p < 0.001), C (p < 0.001 and Bp (p = 0.02). MUCP at rest and MUCP on prolapse reduction were significant predictors of USI and USI grading (all p < 0.001). MUCP on prolapse reduction was not markedly superior to MUCP at rest in the association with USI grading (Nagelkerke R² = 0.14 and 0.13 respectively).

Symptoms of splinting and objective prolapse on POPQ predict a lower MUCP on prolapse reduction. However, as the latter does not significantly increase predictive value, prolapse reduction is probably unnecessary in clinical practice.