Transvaginal ultrasound guided trigone and bladder injection: A cadaveric feasibility study for a novel route of intradetrusor chemodenervation

Purpose: OnabotulinumtoxinA (BTX) detrusor chemodenervation is an efficacious third-line treatment for overactive bladder. Despite high clinical efficacy rates for BTX injection, many patients refuse initial or repeat treatment due to the invasiveness of the cystoscopic route of delivery. We assess the feasibility of injecting the trigone and posterior bladder wall via a transvaginal route under ultrasound guidance using a human cadaveric model. Materials and Methods: Eight de-identified anonymous fresh female deceased donor cadaver pelvises were placed in supine split leg position. A transvaginal ultrasound probe guided injections of India ink into the trigone in 3 sites and the posterior wall in 2 sites. Full thickness bladder biopsies were then obtained and histologic analysis was performed to confirm presence of India ink in the detrusor layer. Results: The mean time from day of death was 11.0 days (range, 4.0-23.0 days). Three to five bladder biopsies were obtained per cadaver, for a total of 34 specimens (20 trigone, 14 posterior wall). Histologic analysis revealed presence of India ink within the detrusor layer in 8/8 (100.0%) of cadavers. The surgeon's perception of appropriate targeting under ultrasound guidance was confirmed in 8/8 cadavers (100.0%) involving the bladder trigone, and 7/8 (87.5%) involving the posterior wall. Of injections that were believed to have appropriately targeted the detrusor layer, 22/34 specimens (64.7%) demonstrated the presence of India ink under histologic analysis. Conclusions: Intradetrusor injection of the bladder trigone and posterior wall under transvaginal ultrasound guidance is feasible and has acceptable accuracy.