Many studies looking at adverse outcomes for females post intravesical OnabotulinumtoxinA report on populations who do not represent a typical cohort entering into a urologists rooms. This study's purpose is to review the rates of urinary retention requiring intermittent catheterization (IC) post intravesical OnabotulinumtoxinA (BTN/A) injection for idiopathic overactive bladder (iOAB), with inclusion of patients with mixed symptoms who had previously undergone pelvic or other bladder surgery.

Study methodology utilised a retrospective review of a single Australian urologist. The two primary outcomes were post-void residual (PVR) post 100units of intravesical OnabotulinumtoxinA and the other was identifying rate of intermittent catheterization within this cohort. Electronic medical records were collected for all female patients who underwent intravesical OnabotulinumtoxinA for management of idiopathic detrusor overactivity. Patient data was retrospectively collected from February 2016 to March 2021. Neurogenic OAB patients were excluded. Further exclusion for patients if they did not have a complete preoperative urodynamic assessment available for analysis, previous history of IC, prior retention or if lost to follow upLogistical regression was employed to establish statistical significance.

94 patients were included after inclusion and exclusion criteria were applied and the average age was 69.7 years (SD 17.2) and all participants were female. 36% (n=34) of patients required IC. Of patients requiring IC, 32% had a prior sling, 35% had prior vaginal prolapse surgery, and 29% had a preoperative UTI. There is strong evidence of an association between prior sling and IC (OR 6.69, 95%CI 1.57-30.91, p-value 0.011), and mild evidence of association between preoperative urinary tract infection (UTI) and IC (OR 3.97, 95%CI 0.93-16.94, p-value 0.062).

The risk of requiring IC was 7 times larger for patients with prior mid urethral sling surgeries and 4 times larger for patients found to have a positive preoperative UTI despite appropriate antimicrobial therapy, a common management challenge for the urological surgeon. Perhaps the asymptomatic bacteriuria may be indicative of mild voiding dysfunction.

Despite being limited by retrospective methodology, these results are in line with internationally recognized studies with similar rates of intermittent catheterization post 100units OnabotulinumtoxinA, which are up to six times those reported from Chappel et al.

Prior urethral sling surgery, prior vaginal prolapse surgery and positive preoperative UTI, despite treatment, were found to be associated with a higher rate of initiation of intermittent catheterization. The rate of IC initiation of 36% was higher than reported in prior clinical trials. 
No conflicts of interest to declare

Chapple C, Scott, Sievert KD FAU - MacDiarmid, MacDiarmid S FAU - Khullar, Vik, et al. OnabotulinumtoxinA 100 U significantly improves all idiopathic overactive bladder symptoms and quality of life in patients with overactive bladder and urinary incontinence: a randomised, double-blind, placebo-controlled trial. European urology JID - 7512719.