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Objective: To determine whether endometrial thickening is an important factor for pregnancy outcomes in platelet-rich plasma (PRP) treatment for patients with thin endometrium. Methods: Data from the registry database of the Japan Gynecologic PRP Study Group from April 2019 to October 2021 were analyzed retrospectively. A total of 208 patients who underwent single blastocyst transfer (SBT) after PRP due to thin endometrium (¡8 mm) in their previous cycle were included in the study. Their pregnancy outcomes were compared with their own historical data before PRP infusion. The same patient group was then divided into 136 patients whose endometrium thickened after PRP and 72 patients whose endometrium did not, and the pregnancy outcomes of the two groups were compared. Furthermore, to eliminate embryonic confounding, 28 patients who had single euploid blastocyst transfer (SEBT) with preimplantation genetic testing for aneuploidy (PGT-A) were selected from the same patient group and divided into two groups of 22 patients whose endometrium thickened and 6 patients whose endometrium did not, and the pregnancy outcomes were compared in the same method. Results: After PRP administration, the clinical pregnancy rate, live birth rate, and miscarriage rate were all significantly improved compared with the historical controls (34.1 vs 20.0, [Formula: see text]; 22.6 vs 3.9, [Formula: see text]; 33.8 vs 73.4, [Formula: see text]). There were no statistically significant differences in the respective rates between the “thickened endometrium” group and the “unthickened endometrium” group in SBT group (36.0 vs [Formula: see text], [Formula: see text]; 25.7 vs [Formula: see text], [Formula: see text]; 28.5 vs [Formula: see text], [Formula: see text], respectively). Likewise, in the SEBT with PGT-A group, there were no statistically significant differences in results between the two groups (36.4 vs [Formula: see text], [Formula: see text]; 36.4 vs [Formula: see text], [Formula: see text]; 0 vs [Formula: see text], respectively). Conclusions: PRP administration to patients with thin endometrium improves pregnancy outcomes even when endometrial thickening is not achieved.

Background and Aims: Little information is available for investigating the effect of the direction of sperm injected into the cytoplasm on clinical results for human oocytes following intracytoplasmic sperm injection (ICSI). This study aimed to examine the impact of the direction of sperm (head-first or tail-first) injected into the cytoplasm on fertilization and embryo development for high-elasticity or low-elasticity human oocytes following the Piezo-ICSI. Methods: We retrospectively investigated 2717 high-elasticity oocytes and 907 low-elasticity oocytes between May 2016 and December 2022. Of 2717 high-elasticity oocytes, 1148 were injected sperm head-first, and 1569 were injected sperm tail-first into the cytoplasm by Piezo-ICSI. Of 907 low-elasticity oocytes, 480 were injected head-first, and 427 were injected sperm tail-first into the cytoplasm. The membrane of high-elasticity oocytes was robust and was ruptured artificially by the piezo-pulse. The membrane of low-elasticity oocytes was weak and spontaneously ruptured without the piezo-pulse. The rates of degeneration, fertilization (2PN), 0PN, 1PN, [Formula: see text]3PN, abnormal cleavage, and good-quality day-3 embryos were evaluated in both groups. Results: Table 1 shows the effect of sperm direction on fertilization and embryo development for high-elasticity oocytes. The fertilization rate of tail-first group was significantly higher than the head-first group. The 0PN rate of tail-first group was significantly lower than the head-first group. The good quality Day-3 embryo rate of tail-first group was significantly higher than the head-first group. Table 2 shows the effect of sperm direction on fertilization and embryo development for low-elasticity oocytes. The fertilization rate of the tail-first group was significantly higher than the head-first group. However, no significant difference was observed in other comparable items. Conclusions: Tail-first sperm injection significantly improved the fertilization rates more than the head-first sperm injection regardless of the elasticity of the oocyte membrane following Piezo-ICSI.

Background: The objective of this study was to investigate accurately the effect of the meiotic spindle imaging of human oocytes on their fertilization and embryo development by using the Piezo-ICSI. Methods: We retrospectively assessed 529 oocytes with the first polar body retrieved from 124 infertile couples (147 cycles) who attended our clinic between May 2016 and December 2018. Of these, 489 oocytes (92.4%) with visible meiotic spindle comprised the Spindle (+) group and 40 oocytes (7.6%) not observed meiotic spindle comprised the Spindle (−) group. The meiotic spindle was imaged using polarized light microscopy. The rates of fertilization, high-quality day-3 embryo, day-5 blastocyst, and high-quality day-5 blastocyst were evaluated in both groups. Results: The fertilization rates of Spindle (+) and Spindle (−) were 92.0% (450/489) and 70.0% (28/40), respectively; high-quality day-3 embryo rates were 62.9% (283/450) and 35.7% (10/28); day-5 blastocyst rates were 53.7% (205/382) and 32.1% (9/28); high-quality day-5 blastocyst rates were 29.8% (114/382) and 3.6% (1/28). Fertilization, high-quality day-3 embryo, day-5 blastocyst, and high-quality day-5 blastocyst rates were significantly higher in the Spindle (+) group than in the Spindle (−) group. Conclusion: Spindle imaging (i.e., oocytes with a visible meiotic spindle or with not observed meiotic spindle) influences the outcome of Piezo-ICSI in human oocytes, including fertilization and embryo development. To our knowledge, this study is the first to evaluate the effect of meiotic spindle imaging on fertilization or embryo development among oocytes after Piezo-ICSI. The meiotic spindle imaging could be the indicator for the quality management of medical doctors and embryologists.