Previous obstetrical history does not impact short-term mid-urethral sling outcomes

Pregnancy and delivery are known risk factors for stress and mixed urinary incontinence. The most common surgical treatment is mid-urethral sling (MUS) surgery. This study evaluated the potential impact of the obstetrical history on the short-term subjective and objective failure rates after MUS surgery.

A registry-based surgical cohort study using data from the Medical Birth Registry of Norway (MBRN) and the national Norwegian Female Incontinence Registry (NFIR). Data from 14,787 women that underwent MUS surgery from 1998 to 2016 with complete registrations in the MBRN were included. Outcomes were 6-12-month postoperative subjective and objective failure rates. The potential impact of obstetrical and constitutional factors on both outcomes was tested in a multivariate logistic regression model.

Several obstetrical variables seemed to impact both outcomes in the univariate analyses. However, in the multivariate analyses, none of the obstetrical variables significantly impacted subjective failure, and only being nulliparous before MUS surgery remained a risk factor for objective failure [aOR 1.60, (95% CI 1.07-2.40), p = 0.022]. High body mass index at time of surgery, non-retropubic slings, high preoperative urgency symptom load, and surgical complications were all strong risk factors for poor outcomes in the multivariate analyses.

Although childbirth is considered a risk factor for developing stress urinary incontinence, childbirth does not appear to affect the result of MUS in parous women. Our results suggest that nulliparous women with SUI may have a different pathophysiology than SUI after childbirth.