High-frequency ultrasound imaging of noninvasive laser coagulation of the canine vas deferens

Background and Objectives A noninvasive approach to vasectomy may eliminate male fear of complications related to surgery (e.g., hematoma, infection, acute and chronic pain, sterilization failure) and increase its acceptance. Noninvasive laser thermal occlusion of the canine vas deferens has recently been reported. In this study, high-frequency ultrasound is used to confirm successful laser thermal coagulation and scarring of the vas in a short-term canine model. Materials and Methods Bilateral noninvasive laser coagulation of the vas was performed in a total of nine dogs using a laser wavelength of 1,075nm, incident power of 9.0W, pulse duration of 500milliseconds, pulse rate of 0.5Hz, and 3-mm-diameter spot. Cryogen spray was used to cool the scrotal skin surface and prevent burns during the procedure. A clinical ultrasound system with a 13.2-MHz high-frequency transducer was used to image the vas before and after the procedure. Burst pressure measurements were performed on excised vas to confirm thermal occlusion. Results Day 0 and 28 burst pressures averaged 291±31mmHg and 297±26mmHg, respectively, significantly greater than ejaculation pressures of 136±29mmHg. Ultrasound showed a hyperechoic vas segment after thermal coagulation (Day 0) and scarring (Day 28). Doppler ultrasound showed normal blood flow through the testicular artery, indicating no collateral thermal damage to proximal structures. Conclusions High-frequency ultrasound may be used as a noninvasive diagnostic tool to assist in determining successful short-term laser thermal coagulation and scarring of the vas.