This retrospective cohort study aims to evaluate the outcomes of individuals undergoing two or more anti-stress urinary incontinence procedures, specifically assessing urinary retention rates, voiding difficulties, and new-onset urge incontinence in patients who receive a mid-urethral sling after Bulkamid injections or Bulkamid injections after a mid-urethral sling.

The study was approved by the institutional review board with no ethical concerns. This retrospective cohort study assessed urinary symptoms outcomes in patients undergoing both Bulkamid injections and mid-urethral sling placement for stress urinary incontinence. A matched control cohort was created based on age and BMI, with a 1:8 ratio for the sling-first group and 1:4 for the Bulkamid-first group. Data were extracted from the electronic medical record, with manual chart review of all patients to confirm eligibility and define outcomes. Urinary retention, voiding difficulties and new onset/worsening overactive bladder were assessed based on postoperative follow-up. Statistical analysis included descriptive statistics, chi-square tests, and logistic regression models to evaluate factors influencing urinary outcomes.

Nineteen patients underwent mid-urethral sling placement preceded by Bulkamid injections (bulkamid-first), compared to 160 patients who received a sling alone. The bulkamid-first group had a higher prevalence of preexisting OAB (47.4% vs. 9.4%, p<0.001). Urinary retention occurred in 21.1% of bulkamid-first patients versus 2.5% in the sling-only group (p=0.005, OR=7.16, 95% CI: 1.18-40.33). No significant differences were observed in voiding difficulties or worsening OAB symptoms between the two groups. Age, BMI, and Bulkamid volume were not associated with urinary retention, while preexisting OAB significantly increased the risk of voiding difficulties (p=0.016, OR=5.42, CI: 1.34–21.68). A separate comparison was performed between 205 patients who underwent Bulkamid injections alone and 45 patients who received Bulkamid injections after sling placement (sling-first). Urinary retention rates in the sling-first group were similar to those in the Bulkamid-only group (8.9% vs. 11.7%, p=0.79), with no significant differences in voiding difficulties or worsening OAB symptoms.

Urinary retention was significantly more common in patients receiving a sling after Bulkamid injections compared to those who had a sling alone, while preexisting OAB was a key predictor of voiding difficulties. None of the patients with retention required long-term (>7 days) indwelling catheterization, self-catheterization, or experienced persistent voiding difficulties. Retention rates did not differ between patients receiving Bulkamid after a sling and those undergoing Bulkamid alone.

Patients undergoing a mid-urethral sling after a prior Bulkamid procedure are at increased risk of short-term urinary retention. No difference in retention rate was noted in patients undergoing Bulkamid after a prior mid-urethral sling.