Impact of spermatozoa cryopreservation upon clinical outcomes of intracytoplasmic sperm injection in patients with azoospermia: a retrospective cross-sectional study

Background: This study was carried out to evaluate the effect of cryopreservation on the clinical outcomes of intracytoplasmic sperm injection (ICSI) cycles using sperm retrieved from testicular sperm extraction (TESE) in patients with azoospermia. Methods: An retrospective analysis was made to the clinical data of 56 pairs of fresh and frozen sperm injection cycles from 56 couples after TESE from January 2019 to December 2021 at the Reproductive Medicine Center of the First Affiliated Hospital of Sun Yat-sen University, of which 42 pairs were ICSI cycles using fresh and frozen sperm from the same TESE procedure. All clinical information is retrieved from our reproductive center's own non-public database. We compared the embryological and laboratory characteristics, and pregnancy outcomes of the subsequent first embryo transfer (ET) cycles between the fresh and frozen groups. Results: There were no significant differences in the fertilization, cleavage, good-quality day 3 embryo, blastocyst formation, and good-quality blastocyst rates between the groups. However, when only paired ICSI cycles of fresh and frozen sperm from the same TESE procedure were analyzed, we observed that the good-quality day 3 embryo rate (44.8% vs. 33.2%, P=0.029) and blastocyst formation rate (57.5% vs. 41.3%, P=0.028) in the fresh group were significantly higher than those in the frozen group. Implantation, clinical pregnancy, early miscarriage, and live birth rates of the first ET cycle were not significantly different in either group. Conclusions: ICSI using fresh testicular sperm after TESE in patients with azoospermia appears to yield better embryological and laboratory outcomes than ICSI using cryopreserved testicular sperm, but the success rate of the subsequent first ET cycles does not seem to be affected.