What maximal urethral closure pressure threshold predicts failure of mid-urethral sling surgery?

Low Maximal Urethral Closure Pressure (MUCP) is linked to unfavourable outcome of anti-incontinence surgery, however the cut-off value varied within studies. This study aimed to predict the cut-off value of MUCP that contributes to poor outcome of Mid-Urethral Sling (MUS) surgery in Urinary Stress Incontinence (USI) patients.

Records of 729 women underwent MUS procedure from January 2004 to April 2017 reviewed. Patients were divided into four MUCP groups, which were <20 cmH2O (≥20 and < 40) cmH2O (≥40 and ≤ 60) cmH2O and >60 cmH2O. Objective evaluation comprising 72-h voiding diary, multichannel urodynamic study (UDS) and post-operative bladder neck angle measurement. Subjective evaluation through validated urinary symptoms questionnaires. Primary outcome was objective cure rate of negative urine leak on provocative filling cystometry and 1-h pad test weight <2 g, and subjective cure rate was negative response to question 3 of UDI-6. Secondary outcome was identifying risk factors of cure failure for MUS in low MUCP groups. To identify the risk factors of cure failure, MUCP groups were narrowed down into <40 cmH2O or ≥40 cmH2O.

Total of 688 women evaluated. Overall objective cure rate was 88.2% with subjective cure rate of 85.9%. Objective and subjective cure rates were lower in groups with low MUCP <40 cmH2O. Failure of MUS correlate significantly in patients with low MUCP <40 cmH20, bladder neck angle <30° and Functional urethral length (FUL) < 2 cm.

Women with MUCP <40cmH2O, bladder neck angle <30° and FUL < 2 cm are more likely to have unfavorable outcome following MUS surgery. We proposed the cut-off low MUCP <40cmH2O as predictor for fail MUS surgery in SUI patients.