Sperm retrieval techniques.

Since the advent of intracytoplasmic sperm injection in 1992, sperm retrieval procedures have been routinely employed to treat male infertility owing to azoospermia. With obstructive azoospermia, sperm is potentially harvestable from the vas deferens, epididymis, and testicle using percutaneous and open sperm retrieval procedures that are relatively straightforward and reliable. In nonobstructive azoospermia, sperm is generally found only in the testicles and can often be difficult to retrieve. Several approaches aimed at maximizing sperm yield in this condition have been developed, but only 50% of men with nonobstructive azoospermia will have clinically usable sperm. Multibiopsy testicular sperm extraction (TESE), microdissection TESE, and fine-needle-aspiration map-guided TESE are three common methods currently employed to locate and retrieve sperm in these difficult cases. Other factors that influence the use of surgically retrieved sperm for assisted reproduction include differences in sperm DNA integrity, the expertise of the surgeon and the andrology laboratory, and the described differences in the viability of sperm from different anatomical sources after freezing and thawing.