Predictors of 2‐Week Post‐Void Residual After Intradetrusor OnabotulinumtoxinA Injection for Overactive Bladder: A Sex‐ and Neurogenic Status‐Stratified Analysis

ABSTRACT Objective Urinary retention rates after intradetrusor onabotulinumtoxinA (BTX‐A) peak at 2 weeks, yet risk stratification by sex and neurogenic status remains limited. We evaluated predictors of 2‐week post‐void residual (PVR) and differences by sex and neurogenic bladder status using the largest retrospective cohort to date. Methods We reviewed all BTX‐A procedures at a single academic institution from January 2020 to June 2025. Patients younger than 18 years, those with mean preprocedural PVR ≥ 150 mL, prior pelvic radiation, or preprocedural catheterization requirements were excluded. Two‐week PVR was analyzed using multivariable regression of demographics and urodynamic parameters, adjusting for total injections per patient, with subgroup analyses by sex‐assigned‐at‐birth and neurogenic status. Results A total of 824 patients underwent 2282 BTX‐A injections. The cohort was predominantly female (95.9%) and non‐neurogenic (93.7%), with mean preprocedural PVR of 24 mL, mean BTX‐A dose of 120.8 units, and mean 2‐week PVR of 66.7 mL. Higher preprocedural PVR was associated with higher 2‐week PVR among female patients (β = 0.593 mL, 95% CI [0.303, 0.883]) and non‐neurogenic patients (β = 0.555, 95% CI [0.284, 0.825]), but not among male or neurogenic patients. Higher BTX‐A dose was similarly associated with higher 2‐week PVR among female patients (β = 25.7 mL per 100 U, 95% CI [6.16, 45.2]) and non‐neurogenic patients (β = 28.1 mL per 100U, 95% CI [10.5, 45.6]). Lower maximum flow rate (Qmax) was associated with higher 2‐week PVR among female patients (β = −1.25 mL per mL/sec, 95% CI [−1.94, −0.56]), neurogenic patients (β = −17.4, 95% CI [−31.5, −3.26]), and non‐neurogenic patients (β = −1.08, 95% CI [−1.74, −0.418]). Higher detrusor pressure at maximum flow (pDet@Qmax) was associated with higher 2‐week PVR among female (β = 0.557 mL/cmH 2 O, 95% CI 0.136, 0.979]) and neurogenic patients (β = 2.68 mL/cmH 2 O, 95% CI 0.126, 5.23]), whereas lower pDet@Qmax was associated with higher PVR among male patients (β = −8.34 mL/cmH 2 O, 95% CI −12.9, −3.76]). Conclusions Pre‐procedural PVR and BTX‐A dose were consistent predictors of elevated 2‐week PVR in females and non‐neurogenic patients. These findings support sex‐ and neurogenic‐specific risk stratification and dose considerations prior to BTX‐A injection.