Idiopathic overactive bladder (iOAB) is a debilitating condition. The negative impact on quality of life and the economic related burden to the patient and the health care system associated with OAB is well known.  Intravesical OnabotulinumtoxinA (BTN/A) injections are a well-used treatment modality for management of overactive detrusor refractory to medical management, with well documented efficacy and safety profiles. 
In a large and comprehensive regional health service in the Southwest Region of Victoria Australia, the majority of cases undergo an intraoperative method for iOAB of intravesical BTN/A which is, 100units of BTN/A diluted in 20ml injected in 20 aliquots, sparing the trigone. This, in the majority, is done with a rigid or flexible cystoscope and under general anaesthetic. 
There is currently no best practice guideline for the technique of this procedure. The trigone has been historically excluded from the injection paradigm given the risk of vesicoureteric reflux (VUR).  
A systematic scoping review was conducted to review what evidence is available on BTN/A for iOAB regarding inclusion of the trigone and reducing the number of injection sites whilst maintaining the efficacy and safety profile of the procedure. This study aims to provide a basis for further research into improving the intraoperative methods of intravesical BTN/A for patients with iOAB.

A systematic scoping review methodology was employed to assess the literature available to potentially  improve this technique. There is evolving literature that inclusion of the trigone may have a similar adverse effect profile and increase the efficacy of the procedure, and that similar results can be obtained by decreasing the number of injection sites while maintaining the efficacy. A systematic scoping review was completed using the PRISMA-SCr checklist. A systematic search was conducted in November of 2021. The search systematic scoping strategy was conducted to investigate idiopathic overactive bladder, botox and number of injections sites and inclusion of the trigone. The search strategy was conducted with the assistance of a specialist research librarian and consulted upon with the supervising urologist. A combination of MeSH and natural language terms. The terms “botulinum toxin” “bladder” “intravesical” “overactive” “incontinence”, “injection” “trigone” and “idiopathic” were utilised and adapted to each database. The search strategy was run on Medline, PubMed, Embase, Cocrahne trials and Google Scholar. Two investigators independently reviewed the titles and abstracts and then full text articles. One investigator conducted data analysis.

Fifteen articles were included and were published between 2005 and 2021. From seven countries; Taiwan, United Kingdom, United States, South Korea, Spain, China and Canada. There were three systematic review articles, all of these focused on inclusion or exclusion of the trigone . A further five prospective randomised controlled trials investigated the inclusion or exclusion of the trigone. Three prospective studies explored the number of injection sites. A further three studies looked at the inclusion of the trigone and the number of injections and included a retrospective chart review, a prospective pilot study and evidence from a not-yet-published randomised control trial.

There was no evidence of VUR in any of the results. All but one study reported similar if not improved efficacy and safety profiles of trigone inclusion injections. Reducing the number of injection sites had similar efficacy profiles to higher numbers of intravesical injections.

Further high quality randomised control trials of trigone inclusion and reduction of injection sites are required. It is hoped that these changes to the intraoperative methods of the procedure could see increased accessibility to BTN/A for iOAB patients  in the Australian landscape.

Continence 7S1 (2023) 100957
DOI: 10.1016/j.cont.2023.100957