Mid-urethral sling surgery is a commonly performed for stress urinary incontinence (SUI) or stress-predominant mixed urinary incontinence (MUI). However, there is a subset of patients with overactive bladder (OAB) symptoms who undergo MUS surgery without strong clinical indications. Furthermore, we observed that following sling removal for complications including pain, bladder outlet obstruction, erosion and exposure, overactive bladder and specifically, urge incontinence was one of the most debilitating symptoms which was also relatively treatment refractory.  This study aims to compare the urinary incontinence outcomes after mesh removal surgery between patients with OAB symptoms compared with those with SUI/MUI.

A retrospective/prospective database of mesh complications from Aotearoa New Zealand from 2012 to present was utilised. A combination of radiological, urodynamic, operative procedures and complications were assessed. Pre-operative clinical letters were used to establish the study groups. Patient reported outcome measures (PROMS) were collected post-operatively, and statistical analysis was undertaken with Stata.

From 400 database patients, 291 patients had undergone mesh removal surgery for mesh sling complications, with 216 responding with post-operative PROMS. 
Of 291 patients who underwent mesh removal surgery, 32 had OAB symptoms prior to the sling, while 184 had SUI/MUI. Clinical symptoms and urodynamic findings were different between the two groups. Patients with OAB had more severe urinary incontinence post-operatively compared to the SUI/MUI group despite similar rates of bladder outlet obstruction (p = 0.031). Rates of intervention for incontinence was higher in the OAB group, but mitigate the severity of the urinary incontinence.

Our study reports on a cohort of patients who have overactive bladder symptoms with no SUI/clinically insignificant SUI treated with mid-urethral sling surgery (with subsequent mesh complication).  We have encountered this in clinical practice but have not seen this reflected in peer-reviewed literature.  
From our data, it seems that where slings are placed an OAB, which is outside accepted indications, and result in a mesh complication, there are poorer continence outcomes in the medium term.  This appears to create a very difficult clinical entity where removal of a possibly obstructing/tight sling (29-37%) does not appear to have similar benefits to the SUI/ MUI indication group.  
Furthermore, surgical treatment for the “original” problem of OAB after mesh removal, does not appear to significantly mitigate urinary incontinence severity.   Severe and very severe incontinence was high in both groups, but significantly higher in the OAB group at 66% compared to 40% in the SUI group. 
This underscores the importance of adequate clinical assessment and subsequent patient selection for this surgery. High-quality education around urinary incontinence is crucial to prevent adverse outcomes.

Our study highlights the need for accurate and appropriate assessment and identification of clinical indications before performing MUS surgery. Patients with OAB who undergo MUS surgery without strong indication may experience worse outcomes of urinary incontinence. This highlights the importance of accurate clinical assessment and patient selection.

Continence 12S (2024) 101560
DOI: 10.1016/j.cont.2024.101560