Does sperm origin-Ejaculated or testicular-Affect embryo morphokinetic parameters?

Abstract

Background: It is unclear whether sperm origin, either ejaculated or testicular, in couples diagnosed with male factor infertility, affects the timing of the embryo's developmental events evaluated by time-lapse monitoring and implantation rates.

Objective: To examine the effect of sperm origin on embryo morphokinetics in couples diagnosed with male factor infertility.

Materials and methods: This study included a retrospective analysis of morphokinetic parameters performed by time-lapse monitoring between 2013 and 2017. The developmental processes and morphokinetic parameters of 419 embryos obtained from couples with male factor infertility attributed to oligo-astheno-teratozoospermia, 158 embryos derived from surgically extracted testicular spermatozoa from couples diagnosed with non-obstructive azoospermia, and 190 embryos from couples with normal ejaculated spermatozoa and female mechanical factor-related infertility, were evaluated. A comparison of morphokinetic parameters, implantation, and clinical pregnancy rates was performed between the groups with additional analysis in accordance with implantation status.

Results: Embryos from the normal ejaculated spermatozoa and oligo-astheno-teratozoospermia patients reached the later morphokinetic milestones-synchronous division (S3) and time to morula (tM)-faster than embryos obtained from testicular spermatozoa. Implantation rate was similar in the normal ejaculated spermatozoa and oligo-astheno-teratozoospermia groups (41.9% vs. 45.8%, NS), with higher implantation rate in the oligo-astheno-teratozoospermia group compared to the testicular spermatozoa group (45.8% vs. 33.6%, p = 0.02). Comparison of Known Implantation Data (KID) positive (KIDp) and KID negative (KIDn) embryos in each group revealed more rapid development in KIDp embryos in the normal ejaculated spermatozoa and the oligo-astheno-teratozoospermia groups, while in the testicular spermatozoa group implanted embryos reached the late morphokinetic milestones (time to 8 cell stage-t8, ECC3, S3, and tM) significantly faster than embryos that failed to implant. In a multivariate logistic regression analysis of the male factor infertility population, (oligo-astheno-teratospermia) (OR = 2.54, p = 0.003) and t8 (OR = 0.95, p = 0.027) were predictive of successful implantation. Male factor infertility embryos that reached the t8 milestone within 48-56 h had favorable implantation rates (p < 0.001).

Discussion: The study results may highlight another pathophysiology by means of which sperm origin affects embryo developmental kinetics. Selecting embryos demonstrating a faster developmental rate at t8 and specifically the 48- to 56 h interval following time of pronuclei fading (tPNf) may improve implantation rates in cases of male factor infertility.

Conclusion: This study showed that ejaculated spermatozoa is associated with faster late cell divisions, more rapid compaction, and higher implantation rates compared to testicular spermatozoa. Additionally, t8 is an important predictor for implantation in the male factor infertility population.

Keywords: azoospermia; male factor infertility; morphokinetics; oligo-astheno-teratozoospermia; time-lapse monitoring.