(076) An MRI-Based, Anatomic Description of the Distance from the Urethral Meatus to the Anal Verge in Cis and Transgender Women: A Cause for Higher UTI Rates in Transgender Women?

Introduction Patients undergoing vaginoplasty for gender-affirmation require reconstruction of their anatomy. One key anatomic structure is the urethra position. It is known that transgender women (TW) are more likely to develop urinary tract infections as compared to cisgender women (CW) (12% vs. 29%). Several considerations of an elevated risk could be related to the anatomic differences between a natal vulva and reconstructed vulva, the differences in commensal bacteria present in the vaginal canal and the need for repetitive dilation and douching for transgender women. No published reports have evaluated the anatomic difference between CW vulvar anatomy as compared to transgender women’s vulvar anatomy (extrapolated from natal male anatomy), Objective Evaluate specifically the distance between the urethral meatus and anal verge in cis gender and transgender patients. Methods We reviewed MRI scans of individuals with natal male and female anatomy to determine the distance of the native urethra (in CW) and neourethral meatus (in TW, extrapolated from natal male anatomy). The distance was calculated as a direct line between these two structures. Statistical analysis using an unpaired T-Test was used. Results MRIs of 25 CW with normal genital anatomy and 28 individuals with natal male anatomy (surrogate for TW) were reviewed. Mean distance from the urethral meatus to the anal verge was found to be 42.6±6.4mm (range: 32.5–55.9mm) in cisgender female anatomy and mean distance from the neourethral meatus position for TW to the anal verge based on natal male anatomy was 33.5±6.1mm (range: 24.6–52.9mm) (p<0.0001). Conclusions We note a difference in the distance of the neourethral meatus to the anal verge in transgender women as compared to cisgender women. This anatomic difference can be potential cause for increased UTI rates in addition to other factors. This shows the importance of reducing bacterial burden by voiding regularly throughout the day, and also after dilation, douching and vaginal intercourse, and finally the importance of wiping away from the urethra to prevent bacterial colonization. Disclosure No