Technical aspects of botulinum toxin type A injection in the bladder to treat urinary incontinence: reviewing the procedure

AIMS: Standardise the injection technique with botulinum toxin type A (BoNT A) in the bladder of patients with overactive bladder (OAB) [idiopathic overactive bladder (iOAB) or neurogenic overactive bladder (nOAB) with urinary incontinence], using a literature review and a survey of an International expert panel. METHODS: PubMed literature searches of BoNT A in adults with iOAB/nOAB together with a survey of 13 experts from 10 countries. RESULTS: Data from 21 articles and completed questionnaires were collated. The procedure can be carried out in an out-/inpatient setting. Dose used in clinical studies vs. clinical practice was 300 and 200 U for nOAB and 200 and 100 U for iOAB. Recent studies have also demonstrated that there are no clinically relevant benefits between 100 and 150 U in iOAB or between 300 and 200 U in nOAB, though adverse effects are increased with higher doses. Usually, 30 sites for nOAB (range: 6.7-10 U/ml) and 20-30 sites for iOAB (range: 5-10 U/ml) are injected in clinical studies vs. 20-30 sites of 1 ml/injection for 200 U in nOAB and 10-20 sites of 0.5-1 ml/injection for 100 U in iOAB in clinical practice. BoNT A is usually injected directly into the detrusor, sparing the trigone. Flexible or rigid cystoscopes are used. The needle should be typically 22-27 gauge and 4 mm in length and should have a stopper to avoid any leakage or perforation of the bladder wall while ensuring a targeted injection. CONCLUSION: Based on the literature and survey analysis, recommendations are proposed for the standardisation of the injection procedure.