(Poster 108) Urinary Retention After Intradetrusor Botox Injection for Overactive Bladder

Objectives: To determine risk factors for development of urinary retention following intradetrusor onabotulinum toxin A (Botox) injection for treatment of overactive bladder (OAB).

Methods: We performed a multi-site retrospective cohort analysis of adult female patients who underwent intradetrusor Botox injection(s) for OAB (CPT 52287) in the office and/or operating room between January 2013 and January 2024. The primary outcome measure was postoperative urinary retention, defined as postvoid residual volume (PVR) >150cc at follow-up visit. Secondary outcomes included urinary tract infection (UTI) at 1 and 3 months postoperatively. Patient demographic information, comorbidities, concurrent OAB treatment, indication for intradetrusor Botox (urinary urge incontinence, neurogenic OAB, dry OAB), urodynamic (UDS) parameters, and Botox dose were recorded and compared between cohorts who did and did not develop urinary retention. Multivariable logistic regression was performed to explore patient factors associated with urinary retention.

Results: Of 602 patients who met inclusion for the study, 48 patients (8.1%) developed post-Botox urinary retention. The majority (76.7%) of patients with retention were managed with timed voids followed by clean intermittent catheterization (16.3%) and indwelling foley catheter (7.0%). Patients who developed urinary retention received a median of 100 Botox units (IQR 100-100) and had a median PVR of 252mL (IQR 200-325) at time of diagnosis. Nearly half of these patients (48.8%) went on to receive subsequent intradetrusor Botox injections. Rates of mixed urinary incontinence (48.9% vs.52.2%, p=0.782), neurogenic OAB (22.2% vs 27.1%, p=0.476), diabetes (27.3% vs. 18.8%, p=0.265), and average pre-operative PVR (40.2mL vs. 41.0mL, p=0.928) did not differ significantly between patients who did and did not develop urinary retention. UDS parameters including maximum flow rate, average flow rate, bladder capacity, compliance, and detrusor leak point pressure were also similar between cohorts (p >0.05). Patients who developed urinary retention had lower rates of obesity (35.4% vs. 57.2%, p=0.006) than patients without retention. On multivariable logistic regression controlling for age and indication for Botox (UUI, OAB without UUI and neurogenic bladder), only obesity (aOR 0.43, 95% CI 0.23 – 0.79) was associated with urinary retention after the first Botox injection. More specifically obesity was associated with a 57% lower likelihood of developing urinary retention following the first Botox procedure compared to patients who were normal or overweight.

Conclusions: While preoperative UDS parameters and indication for intradetrusor Botox were not associated with developing urinary retention in this large multi-site cohort analysis, obesity was associated with reduced odds of developing urinary retention.

Table 1 legend: Values in mean ± SD or n(%); BMI (body mass index), SD (standard deviation), DO (detrusor overactivity), UDS (urodynamics), PFPT (pelvic floor physical therapy), BF (biofeedback), PTNS (percutaneous tibial nerve stimulation), SNM (sacral neuromodulation). *Post-Botox retention data was incomplete for 12 subjects.

Table 2 legend: OR (odds ratio), CI (confidence interval)