Microdissection testicular sperm extraction (micro-TESE) in men with infertility due to nonobstructive azoospermia: summary of current literature

Purpose Nonobstructive azoospermia (NOA) is associated with intrinsic testicular defects that severely impair sperm production. Although NOA invariably leads to infertility, focal sperm production may exist in the testicles of affected patients, which can be retrieved and used for intracytoplasmic sperm injection (ICSI) to generate healthy offspring. However, geographic locations of testicular sperm producing-areas are uncertain, making microsurgical-guided sperm retrieval (microdissection testicular sperm extraction; micro-TESE) an attractive method to identify and retrieve sperm in patients with NOA due to spermatogenic failure. Given the widespread use of micro-TESE, its effectiveness in harvesting sperm and related potential complications need to be clarified. Methods We queried PubMed/MEDLINE for studies published in English, from inception to May 2021, concerning the effect of micro-TESE on sperm retrieval rate (SRR), complication rate and ICSI pregnancy rate-using retrieved testicular sperm in subfertile couples where the male had NOA. Results We found 116 articles, including 70 original papers, 32 review articles, and 14 systematic reviews. The evidence accounted for 4895 patients. Micro-TESE retrieved sperm in 46.6% of men with NOA, but SRRs varied considerably (18.4-70.8%) and were mainly related to the treated population characteristics. Concerning the general population of NOA patients who have not undergone previous sperm retrieval (naive population), the SRR by micro-TESE was 46.8% (1833 of 3914 patients; range 20-70.8%; 28 studies). In studies reporting SR by micro-TESE for men who had failed percutaneous testicular sperm aspiration or non-microsurgical testicular sperm extraction, the SRR was 39.1% (127 of 325 patients; range 18.4-57.1%; 4 studies). Data on adverse events indicated that micro-TESE was associated with low (similar to 3%) short-term postoperative complication rates. The fertilizing ability of testicular sperm retrieved by micro-TESE and used for ICSI was adequate (similar to 57%), whereas clinical pregnancy and live birth were obtained in 39% and 24% of couples who had an embryo transfer, respectively. The health of the resulting children seems reassuring, but the evidence is limited. The procedure increases sperm retrieval success compared to non-microsurgical retrieval methods, particularly in men with Sertoli cellonly testicular histopathology. Conclusion We concluded that micro-TESE is an effective and safe method to retrieve sperm from men with NOA-related infertility, with potential advantages over non-microsurgical methods. Nevertheless, high-quality, head-to-head comparative randomized controlled trials by sperm retrieval method, focusing on SRR, live birth rate and assessing long-term adverse events and health of children conceived using testicular sperm from NOA patients are lacking. Therefore, further research is required to determine the full clinical implications of micro-TESE in male infertility treatment.