BERKELEY, CA (UroToday.com) - Overactive bladder syndrome is a disease with serious physical, emotional, and economic consequences. Despite extensive research, the majority of cases remain idiopathic in nature. Involuntary contractions of the detrusor muscle during filling, often without a known cause, occur in most cases, but OAB can also be caused by other forms of urethrovesical dysfunction. In one study, urethral instability was demonstrated in 42% of patients with OAB. In males, benign prostatic hyperplasia is associated with OAB. It is hypothesized that changes to the female urethra may occur over time, such as from repeated bladder infections or trauma during childbirth that may predispose women to the symptoms of OAB.
Urethral dilation has been shown to improve dysfunctional voiding although is has not been widely used in the past for the treatment of OAB. It has been speculated that dilation may theoretically cause bladder outlet obstruction through fibrosis and scarring of the urethral wall. In previous reports, patients were most often dilated up to 30-40 French. Although there is some disagreement over the “normal” caliber of the female urethra, it is generally accepted that an average size urethra is between 22–29 French. In our study we chose to use dilators only up to a size 26-28 French, thus our selection of the term “calibration” rather than dilation as we are returning the urethra to its normal diameter rather than dilating it beyond its normal diameter.
To control for treatment bias, the control group underwent urethral instrumentation with McCrea Infant Sounds. In this way, the groups were blinded to their treatment assignments, but no dilation could have occurred in the control group. As a follow up to the original 8-week study, at the end of 8 weeks, the study participants were unblinded and those in the control group were offered the option of having the treatment done. Thirty-eight of the original 45 participants in the control group accepted. The 83 total participants who had urethral calibration done were followed for an additional 12 months. At 12 months, half of participants still met criteria for the Responsive category and 20% still showed a Partial response. This study is limited by its small sample size, but our long-term results are encouraging. This study also disproves one common concern among some practitioners – that the procedure itself is harmful. No participants over the course of the study developed any strictures or fibrosis. Further studies would be beneficial.
Chao H. Chen, MD;1 Renee Sato, MD;1 Grace Matsuura, MPH;2 and David Wei, MD1 as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
1The Queens Medical Center, Honolulu, HI USA
2John A. Burns School of Medicine, University of Hawai‘i, Honolulu, HI USA