Microepididymal Sperm Aspiration (MESA) is a procedure performed for men who have vasal or epididymal obstruction, a form of obstructive azoospermia caused by vasectomy or a congenital bilateral absence of the vas deferens. MESA allows for an extensive collection of mature sperm for IVF cycles as compared to aspiration techniques, and it is the preferred method of retrieval for men with congenital bilateral absence of the vas deferens as it does not impact steroid production of the testis. MESA is performed in the operating room with general anesthesia utilizing the operating microscope.