Morphokinetic embryo division timings and top-quality cleavage and blastocyst rates are unaffected by sperm quality

Abstract Study question Does testicular extracted sperm affect embryo morphokinetics and the rate of top-quality cleavage and blastocyst embryos. Summary answer Sperm origin, whether ejaculated normal sperm or testicular extracted sperm, was not found to affect embryo morphokinetic timings or top-quality embryo rates. What is known already Time-lapse monitoring (TLM) allows for continuous observation of the developing embryo detecting continuous embryo morphologic and kinetic changes from the zygote to the blastocyst stage. It eliminates potential unnecessary environmental fluctuations and diminishes inter/intra-observer variability compared to the traditional static morphologic evaluation of embryos requiring removal of the embryos from the incubator. Previous studies found sperm origin to affect embryo morphokinetics with some showing slower developmental rates with partially slower morphokinetic milestones with testicular sperm than embryos from ejaculated sperm. Study design, size, duration This retrospective monocentric study evaluated embryos derived from patients using ejaculated normal sperm compared to testicular extracted sperm. Embryo division timings and morphokinetic top-quality embryo rates were defined according to an in-house model for embryo selection based on known implantation data (KID) embryos. Top-quality embryos with the highest chance to implant were defined: tPNf <24.08, t2<26.6, S2<0.9, t8<56 hours post insemination (hPi) for cleavage embryos and t2<26.6, S2<0.9, t8<56 and tSB<96.6 hPi for blastocysts. Participants/materials, setting, methods All patients underwent a GnRH-antagonist ICSI ovarian stimulation protocol between July 2013 - December 2020. Normal sperm parameters were defined according to WHO criteria. Optimal time durations: time to polar body extrusion (tPB2), time to pronucleus fading (tPNf), cleavage timings (t2-t8), synchrony of the second and third cycles (S2 and S3), duration of the second cycle (CC2) time to start blastulation (tSB) were set based on an in-house model including embryos with known implantation data. Main results and the role of chance 1,260 embryos deriving from 450 couples using fresh or frozen ejaculated normal sperm were compared with 556 embryos deriving from 201 cycles of couples with surgically retrieved testicular sperm all undergoing GnRH-antagonist ICSI ovarian stimulation protocol. As for demographic parameters: maternal age and BMI were similar between the groups, yet gravidity was higher in the normal sperm group. The groups differed in certain treatment parameters including a lower gonadotrophin dose, a higher number of oocytes aspirated and a lower fertilization rate in the testicular sperm group. In all time durations evaluated, testicular sperm derived embryos showed comparable morphokinetic milestones to embryos derived from ejaculated normal sperm. Furthermore, there was no difference in the rate of cleavage or blastocyst morphokinetic top-quality embryos between the groups and pregnancy rates were similar. Limitations, reasons for caution To date this is the largest study evaluating the morphokinetic parameters of embryo derived from surgically removed testicular sperm. Furthermore, only GnRH antagonist ICSI cycles were included to standardize the protocol and control for fertilization time. The retrospective nature of the study is a limitation. Wider implications of the findings We did not find the origin and quality of sperm to influence the ability of the derived embryos to reach their morphokinetic milestones on time. Finding patient and treatment characteristics that may influence morphokinetic embryo quality may be of importance in further improving IVF success rates. Trial registration number None