Microsurgical Epididymal Sperm Aspiration (MESA) this procedure is done on male patients that have no sperm in their semen due to a blockage or absence of the vas deferens (the tube that connects the testis and the penis for passage of sperm). The MESA procedure is done under general or local anesthetic with IV sedation and is outpatient, so you can go home the same day. A small incision is made in the scrotum exposing the epididymis (an area on top of the testis where the sperm matures) so that the sperm can be extracted directly from the epididymis. These sperm cells can then be used in ICSI to fertilize the egg.