Assessment of the functional role of accessory pudendal arteries in erection by transrectal color Doppler ultrasound

Purpose: Anatomical studies have demonstrated accessory pudendal arteries originating from supralevator vessels in about two-thirds of men. Injury to accessory pudendal arteries derived from inferior vesical and obturator arteries has been reported to be responsible for vasculogenic impotence after nerve sparing radical prostatectomy. We performed transrectal and perineal color Doppler ultrasound in patients before radical pelvic surgery to identify accessory pudendal arteries and assess their functional role during erection. Materials and Methods: A total of 12 patients with a mean age of 60 years were examined before radical prostatectomy (10) or cystoprostatectomy (2). Transrectal and perineal color Doppler flow imaging and spectral waveform analysis were performed. Peak systolic velocity, end diastolic velocity, resistive index and arterial diameter were measured before and during pharmacologically induced erection. Transrectal color Doppler ultrasound data were compared with intraoperative findings. Results: Transrectal color Doppler ultrasound visualized accessory pudendal arteries derived from supralevator arteries in 9, and prostatic and seminal vesicle arteries in all patients. Perineal color Doppler ultrasound visualized internal pudendal arteries in all patients. After intracavernosal injection of papaverine accessory and internal pudendal arteries displayed similar significant hemodynamic changes. Diameter as well as peak systolic and end diastolic velocities increased, and resistive index decreased. Prostatic and seminal vesicle arteries showed no significant change. Presence and location of accessory pudendal arteries demonstrated by transrectal color Doppler ultrasound were confirmed by intraoperative findings. Conclusions: During pharmacologically induced erection hemodynamic changes in accessory and internal pudendal arteries are similar to those described in cavernous arteries, thus demonstrating the functional role of accessory pudendal arteries in penile erection. Color Doppler ultrasound appears to be reliable to examine internal and accessory pudendal arteries based on morphological and functional criteria.