Azoospermia is defined as the complete absence of sperm in the ejaculate after analysis of two ejaculated specimens. Up to 15% of infertile men are azoospermic, and the etiology can be either obstructive azoospermia (OA) or nonobstructive azoospermia (NOA). OA is estimated to be responsible for 40% of cases of azoospermia and can result from such varied causes as congenital absence of the vas deferens or ejaculatory duct obstruction and iatrogenic etiologies such as vasectomy, injury to the vasa during inguinal surgery, or injury to the epididymis from scrotal surgeries such as hydrocelectomy. NOA comprises the remaining cases and results from failure of the testis to produce sperm. It is imperative that the clinician determine through careful history and exam if the cause is lack of sperm production or obstruction because this will dictate the optimal approach for sperm retrieval. For NOA, only the testis can be targeted for retrieval purposes; however, with OA, the vas deferens, epididymis, and/or testis can likely be used.

OA can be suspected based on history (prior vasectomy or bilateral inguinal surgeries), physical exam (normal testicular volume [>20 mL], absent vasa, or congested epididymides), and laboratory values (normal follicle-stimulating hormone [FSH] [<8 mIU/mL], positive serum antisperm antibody assay, or decreased ejaculate volume [<1.5 mL]) (1). NOA can similarly be suspected based on history (known hypogonadism), physical exam (atrophic testis), and laboratory values (FSH elevated 2 to 3 times upper limit of normal, negative antisperm antibody assay, karyotype anomalies, or Y chromosome microdeletions). In addition, men with ejaculatory dysfunction such as anejaculation or retrograde ejaculation are also candidates for epididymal sperm retrieval, although some of these men may also use less invasive sperm retrieval techniques such as penile vibratory stimulation, electroejaculation, or postejaculatory urine sperm retrieval depending on the etiology of their aspermia. Furthermore, men with obstruction may benefit from reconstruction, particularly if more than one biologic child is desired, because primary reconstruction is more cost-effective than sperm retrieval and repeated in vitro fertilization (IVF) cycles. If the female partner, however, has fertility issues that necessitate IVF and intracytoplasmic sperm injection (ICSI), surgical sperm retrieval may be more appropriate than reconstruction.

There are expected differences in the quality and quantity of spermatozoa retrieved based on the etiology of azoospermia, method of recovery, and tissue of origin. Epididymal sperm is often more mature and motile, whereas testicular sperm is usually immotile except in the case of obstruction. Notably, the virtually limitless supply that is recovered with microsurgical epididymal sperm aspiration (MESA) allows multiple samples that can be frozen for future IVF cycles and has a distinct advantage over the more limited numbers harvested from testicular tissue. The sperm retrieval can be done any time prior to the IVF cycle with multiple vials cryopreserved. Percutaneous epididymal sperm aspiration (PESA) generally has a relatively low yield of sperm, most of which are severely damaged with low motility. Percutaneously retrieved sperm with very poor motility may reduce IVF success rates, and low sperm motility may adversely affect the ability to freeze sperm for future use. Patients should be counseled accordingly regarding this possibility.

Sperm retrieval from men with impaired sperm production (NOA) for use with assisted reproductive technology (ART) is preferentially performed the day before oocyte retrieval, although it can be performed the same day if necessary. Timing is important because all methods of sperm retrieval commit the female partner to ART, and the female can be spared an unnecessary procedure if no sperm are found and the couple defers the use of donor sperm. It is recommended that surplus sperm be frozen for potential use in the future so as to spare the male partner additional procedures. Although it is understood that there is an expected loss of up to half of the frozen spermatozoa during the freeze-thaw process, there is no data to suggest that the sperm which survive the freeze-thaw process are inferior to fresh sperm. In fact, there seems to be no difference in either the fertilization or pregnancy rate from fresh or frozenthawed sperm when men have normal sperm production and are obstructed (2). For men with normal production and obstruction, elective sperm retrieval for freezing prior to the IVF/ICSI cycle may be preferred. For men with NOA, best results are obtained fresh sperm.

Contraindications to sperm retrieval efforts include anyone who cannot undergo scrotal surgery such as men with active groin or urinary infections or men who are not physically able to withstand the stress of surgery. Retrieval is not recommended for men with complete deletions of the AZFa or AZFb regions of the Y chromosome because no patients have had sperm found with these conditions. Relative contraindications include men who have already undergone a failed, thorough bilateral microscopic-assisted testicular sperm extraction (microTESE) by a trained microsurgeon because the chance of successful sperm retrieval in these men is virtually zero.