Hypothesis / aims of study
There is no guideline or consensus concerning pregnancy and delivery after mid-urethral sling (MUS) operation even though this operation is performed also to women at fertile age. Important clinical questions are whether future pregnancy carries a risk for stress urinary incontinence (SUI) relapse or sling exposure problems during pregnancy and how to choose the mode of delivery.
We assessed as the primary outcome the effect of pregnancy after MUS on risk for new SUI re-procedure, and as secondary outcomes, risk for an incontinence-related re-visit and MUS-related complications during post-operative pregnancy and postpartum.
Study design, materials and methods
We conducted a retrospective case-control study that included retropubic and trans-obturator MUS operations in Finland in 1996-2016: 97 cases with a subsequent pregnancy and 340 controls without subsequent pregnancies matched by age, operation type and year. We followed them up until 31 December 2017 and the mean follow-up time was 10.4 years (IQR 7.1-13.8). Data were collected from national health care registers.
The main outcome was new SUI procedures. Secondary outcomes were re-visits for SUI or mixed urinary incontinence after the index operation and complications during pregnancies and post-partum after MUS operation. We were able to identify the time-points of SUI re-procedures and re-visits, and the deliveries. For the case women, we included re-procedures and re-visits if they occurred after the delivery subsequent to the index operation.
Results
The number of re-procedures for SUI did not differ significantly between the case and control groups (3.1% and 5.1%, respectively; OR 0.6, 95% CI 0.2-2.1). Additionally, three cases (3.1%) had a SUI re-procedure before the delivery subsequent to the index MUS operation, but the difference in re-procedure rate remained insignificant even when these re-procedures were included (OR 1.1, 95% CI 0.6-1.8). Of the three cases who had a SUI re-procedure, two delivered vaginally and one had an elective caesarian section after MUS.
There was significantly fewer re-visits for SUI and MUI in the case group (16%) than in the control group (26%; OR 0.5, 95% CI 0.3-1.0, p=0.04). This difference did not remain significant when re-visits between the index operation and the subsequent delivery were included in the case group (OR 1.1, 95% CI 0.6-1.8, p=0.8).
Of the 97 first deliveries after the MUS operation, 56 (57.7%) were vaginal deliveries, 25 (25.8%) were elective caesarian sections and 16 (16.5%) were urgent or emergency caesarian sections. The number of elective and all caesarean section was significantly higher after the MUS operation compared with the last delivery before the MUS operation (p<0.001).
During the pregnancy and postpartum after MUS, 18 cases (18.6%) had a visit for urinary tract infection, urinary incontinence, or pelvic or perineal or lower abdominal pain. There were no visits for urinary retention or other lower urinary tract symptoms.
Interpretation of results
We did not find pregnancy and delivery as a risk factor for a SUI re-procedure or an incontinence related re-visit. It seemed that previous MUS operation did not increase the rate of MUS related complications during pregnancy, delivery and post-partum. Therefore, the results show no reason to regard future pregnancy plans as a contraindication for MUS operation.
Previous MUS operation was likely sometimes viewed as an indication for caesarean section as 42% of the case women delivered with caesarean section after the index MUS operation even though 82% of case women with earlier deliveries had no previous caesarean sections.