Impact of intrinsic sphincter deficiency on mid-urethral sling outcomes

Our primary objective was to study outcomes of patients with intrinsic sphincter deficiency (ISD) following mid-urethral slings (MUS) at 1-year. Our secondary objective was to delineate factors affecting success in these patients.

Six hundred eighty-eight patients who had MUS between January 2004 and April 2017 were reviewed retrospectively; 48 women were preoperatively diagnosed with ISD. All completed urodynamic studies and validated quality-of-life (QOL) questionnaires at baseline and 1 year. Primary outcomes were objective and subjective cure of stress incontinence, defined as no involuntary urine leakage during filling cystometry and 1-h pad test < 2 g and negative response to Urogenital Distress Inventory-6 Question 3. Ultrasound was performed to determine tape position, urethral mobility and kinking at 1 year.

Women with ISD had significantly lower objective and subjective cure rates of 52.1% and 47.9%, respectively, compared to an overall of 88.2% and 85.9%. QOL scores significantly improved in those with successful surgeries. The sling type did not make a difference. Multivariate logistic regression identified reduced urethral mobility [OR 2.11 (1.24-3.75)], lower maximum urethral closure pressure (MUCP) [OR 1.61 (1.05-3.41)] and tape position [OR 3.12 (1.41-8.71)] to be associated with higher odds of failed slings for women with ISD.

Although there are good overall success in women undergoing MUS, those with ISD have significantly lower cure rates at 1 year. Factors related to failure include reduced urethral mobility, low MUCP and relative tape position further away from the bladder neck. Optimal management of patients with ISD and reduced urethral mobility remains challenging.