The First Injection: Rates of Urinary Retention in Women With Urgency Incontinence Treated With Intravesical OnabotulinumtoxinA Injection.

Objective: The aim of the study was to describe the rate of symptomatic and asymptomatic urinary retention and catheterization in women undergoing initial intravesical onabotulinumtoxinA (BnTA) injection for urgency urinary incontinence (UUI).

Methods: This retrospective chart review included women receiving initial 100 U of BnTA injection for UUI for 5 years. Straight-catheterized postvoid residuals (PVRs) were performed 2 weeks after the injection. Women without the sensation of incomplete bladder emptying, worsened urgency, inability to void, or suprapubic pain but with PVR of greater than 300 mL were characterized as having asymptomatic retention, whereas women with a PVR of greater than 150 and any of these symptoms were diagnosed with symptomatic retention.

Results: One hundred eighty-seven 187 patients received initial BnTA injection. The majority were postmenopausal (89%) and white (82%) with a mean age of 65 years and body mass index of 30 kg/m2. One-third of the cohort underwent baseline urodynamic studies. At 2 weeks after injection, 163 patients (87%) followed up, and 17 (10%) had either asymptomatic or symptomatic retention (2% and 8%, respectively). There were no differences in demographic or pretreatment urodynamic parameters in women with and without retention except that women who had previous anti-stress urinary incontinence procedures were more likely to experience retention (53% vs 18%, P = 0.002) despite similar baseline PVRs.

Conclusion: We demonstrated that the rate of retention requiring catheterization after 100 U BnTA may be as high as 10% although only 5% develop PVRs for 300 mL and only 2% have asymptomatic retention for 300 mL.