Evaluating single injection of OnabotulinumtoxinA into the bladder trigone for the treatment of overactive bladder

This study compared the safety and durability of one injection of OnabotulinumtoxinA (Botox; OBT-A) in the bladder trigone vs 20 injections avoiding this region for the treatment of overactive bladder (OAB). Researchers suggested that one OBT-A trigone injection is a safe and durable treatment option for these patients.

OAB causes a frequent urge to urinate that is difficult to control. It may also include urinary incontinence (leakage of urine). This condition is present in up to a quarter of the US population and significantly affects the quality of life of patients. The first-line treatments are behavioral and pelvic muscle training and medication (which is also second-line treatment). However, 65 to 86% of patients stop treatment within one year due to low response and/or side effects to medical treatments.

The most common third-line treatment is OBT-A injections into the bladder. This treatment helps to reduce the uncontrolled contraction of the bladder muscle that causes urinary urgency. Prior studies showed the effectiveness and safety of this therapy in the treatment of urinary symptoms. However, within 6 months of injections, about a third of patients have side effects such as painful urination. 

The trigone is an internal smooth region of the bladder that increases in size when the bladder is full. Injections in this area are associated with fewer urinary retention cases. Normally, OBT-A injections avoid this area of the bladder. It is not known if delivering the OBT-A injection directly into the trigone would improve OAB symptoms in patients with unresponsive OAB.

This study included information about 45 women with unresponsive OAB. All patients underwent OBT-A treatment. 19 patients received one trigone injection (group 1) and 26 received 20 non-trigone injections (group 2). The main outcomes were injection interval, procedure time, residual urine, urinary infections, and retention.

No difference in injection intervals or urinary infections were observed between both groups. Group 1 had lower residual urine after void (113 ml) when compared to group 2 (160 ml). A lower number of patients (23%) with residual urine after a void of more than 150 ml was observed in group 1 when compared to group 2 (39%). Group 1 also had a lower rate of urinary retention (5.3%) than group 2 (17.4%), and a shorter procedure time (4.3 minutes) than group 2 (5.7 minutes).

The procedure time was lower in group 1 (4.3 minutes) than in group 2 (5.7 minutes). 

This study concluded that one trigone injection is a safe and durable treatment for patients with overactive bladder.

This study was done in only one medical center. The number of participants and follow-up time were small. Further studies with a bigger population are necessary.