To investigate the efficacy and safety of modified botulinum toxin type A (BoNT-A) injections (with additional periurethral injection [PUI] of BoNT-A) for the treatment of interstitial cystitis/bladder pain syndrome (IC/BPS).

This single-center, retrospective cohort study included 52 adult female patients with IC/BPS, with 24 patients receiving conventional BoNT-A injections and 28 receiving modified BoNT-A injections. The primary outcome measure was patient-reported global response assessment. Secondary outcomes included daytime frequency, nocturia, number of urinary urgency episodes in the voiding diary, pain visual analog score, O′Leary–Sant interstitial cystitis symptom index and interstitial cystitis problem index, pelvic pain and urgency/frequency scores, risk factors for recurrence, and postoperative recurrence-free time.

The median duration of follow-up was 16.0 months (interquartile range 11.75-21 months). Patients who underwent modified BoNT-A injections showed significant improvement in postoperative global response assessment, symptom questionnaires, and pain assessment compared with those who underwent conventional surgery. A statistically significant difference was observed between the 2 groups in terms of recurrence-free time (12.5 vs 18.0 months, P = .02). Subgroup analysis suggested that additional PUI of BoNT-A was more effective in patients with combined severe periurethral pain. No serious complications occurred in both groups, and all minor postoperative complications were temporary.

Modified BoNT-A injection is an effective treatment for IC/BPS that significantly reduces pain and improves voiding symptoms. It is particularly effective in patients with combined periurethral pain. In such patients, PUI of BoNT-A should be added to the routine intravesical injection of BoNT-A.