TESE or testicular sperm extraction is a surgical biopsy of the testis whereas TESA or testicular sperm aspiration is performed by inserting a needle in the testis and aspirating fluid and tissue with negative pressure. The aspirated tissue is then processed in the embryology laboratory and the sperm cells extracted are used for ICSI.

Testicular sperm extraction is indicated for patients in whom there is a blockage in the epididymis very near the testis (either from prior surgery, infection or from birth), or a blockage within the ducts of the testes (efferent ductules).

It is also used for men with extremely poor sperm production, in which so few sperm are produced that they cannot reach the ejaculate.