Bladder Botox Injection

Intravesical injection of onabotulinumtoxinA (Botox) into the detrusor is a treatment for overactive bladder / urge urinary incontinence and neurogenic detrusor overactivity refractory to behavioural therapy and medications. It is delivered cystoscopically as an office or operating-room procedure. The OAB algorithm and drug therapy are covered in the Functional Urology topic; this page is the procedural reference.

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Indications and Mechanism

• A third-line option for refractory OAB (after conservative measures and antimuscarinic/β3 medications fail), for idiopathic or neurogenic detrusor overactivity and urge incontinence.
• Mechanism — it blocks presynaptic release of acetylcholine from the nerve terminal, producing a flaccid paralysis of the detrusor; bladder afferent (sensory) pathways are also thought to be involved.
• Counsel that the effect is temporary, needing reinjection every 6–9 months, and that catheterisation (intermittent or indwelling) may be needed — reassure that this is transient.

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Contraindications

Active urinary tract infection (do not inject — confirm a clean urinalysis/culture first), urinary retention, inability or unwillingness to catheterise, and hypersensitivity. Avoid aminoglycosides around the time of treatment (they potentiate the neuromuscular block).

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Dose and Preparation

• Dose — 100 U for idiopathic OAB and 200 U for neurogenic detrusor overactivity; reconstitute per the manufacturer and dilute to 0.5–1 U/mL.
• Screen for infection — obtain a urinalysis and culture beforehand; do not proceed with a UTI present.
• Anaesthesia (ambulatory) — instil a dilute intravesical anaesthetic (2% lidocaine in 30–60 mL saline, dwell 20–30 minutes) plus intraurethral lidocaine jelly; alternatively perform under general anaesthesia for selected patients.

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Injection Technique

1. Position and scope — lithotomy for women (rigid cystoscope) or supine for men (flexible cystoscope); prep as for office cystoscopy.
2. Needle — injection needle tips range 4–8 mm; a 4-mm tip is preferred to minimise extravesical injection of toxin.
3. Template — most use a trigone-sparing pattern because of the theoretical risk of vesicoureteral reflux with a transtrigonal technique (a risk not borne out in studies; trigone injection may even improve symptom control, but the evidence is conflicting).
4. Inject — for idiopathic OAB, 20 sites of 0.5 U/mL with 1 mL per site (total 100 U); for neurogenic detrusor overactivity, 200 U at 1 U/mL across 20–30 sites.
   • Work in a bottom-up sequence to preserve visualisation as injection sites bleed, raising a bleb at each detrusor site.

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Postprocedure

• Observe for 30 minutes to confirm the patient can void or catheterise, that hematuria is not severe, and that blood pressure is stable.
• Counsel that benefit may take ≥ 2 weeks to appear (a clinical effect can be seen as early as 48–72 hours).
• Follow up in clinic at 4–6 weeks to check bladder emptying and the response to therapy.

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Complications

• Elevated post-void residual / retention — temporary catheterisation is needed in 6–18% of idiopathic and up to 39% of neurogenic patients (the topic cites ~5–6% with frank retention requiring CIC in idiopathic OAB); it is transient.
• Other — UTI and hematuria; reaffirm that aminoglycosides are avoided around treatment.