Sperm retrieval refers to procedures to obtain viable sperm from the male reproductive tract. The collected sperm are used for in-vitro fertilization (IVF) usually in combination with intracytoplasmic sperm injection (ICSI).

Sperm retrieval procedures are reserved for men with severe male factor infertility including no sperm in their ejaculate (azoospermia) or sperm that are not motile or are dead (necrospermia).

MESA stands for microsurgical epididymal sperm aspiration. MESA is one of the advances in fertility medicine of sperm retrieval in those men with an obstruction in the male reproductive tract. MESA retrieves sperm from the epididymis. The epididymis is the complex of tubules above the testicle where the sperm are stored is isolated through a small incision in the scrotal skin. One of the very small tubules of the epididymis that contain the sperm is opened and the fluid is collected and examined for the presence and quality of sperm. The sperm is collected and taken to the IVF lab for processing, use and freezing for IVF/ICSI.

MESA sperm retrieval gives recovery of the best quality and highest quantity of sperm compared with the other sperm retrieval techniques. MESA is also the safest procedure with the least complications. Most patients recover from MESA within 1 day and can return to work and daily activities.

MESA is usually available only at centers specializing in the treatment of infertility because of the need for specialized equipment and personnel, an operating suite and a trained infertility surgeon. MESA is more cost effective than other sperm retrieval techniques because it is usually a one-time expense whereas the other sperm retrieval techniques may need to be repeated multiple times.

Compare for example, PESA, which is percutaneous epididymal sperm aspiration. PESA is less expensive than MESA. While PESA is appealing, very few sperm are actually collected for use and rarely are enough sperm obtained for freezing. Frequently a second different type of procedure had to be performed to save the IVF cycle because PESA failed to yield usable sperm. PESA is a blind procedure in that the surgeon can not see where he is placing the needle in the epididymis. It may strike a blood vessel causing bleeding and result in a blood collection called a hematoma. PESA is rarely recommended because of poorer results and possible higher rate of complications.