Background Transfer of embryos at the blastocyst stage is one of the best approaches for achieving a higher success rate in In vitro fertilization (IVF) treatment as it demonstrates an improved uterine and embryonic synchrony at implantation. Despite novel biochemical and genetic markers proposed for the prediction of embryo viability in recent years, the conventional morphological grading of blastocysts remains the classical way of selection in routine practice. This study aims to investigate the association between the morphological features of blastocysts and pregnancy outcomes. Methods This prospective study included women undergoing single or double frozen blastocyst transfers following their autologous cycles in a period between October 2020 and September 2021. The morphological grades (A—good, B—average, and C—poor) of inner cell mass (ICM) and trophectoderm (TE) of blastocysts with known implantation were compared to assess their predictive potential of pregnancy outcome. It was further explored by measuring the relationship between the two variables using logistic regression and receiver operating characteristic (ROC) analysis. Results A total of 1,972 women underwent frozen embryo transfer (FET) cycles with a total of 3,786 blastocysts. Known implantation data (KID) from 2,060 blastocysts of 1,153 patients were subjected to statistical analysis, the rest were excluded. Implantation rates (IR) from transfer of ICM/TE grades AA, AB, BA, BB were observed as 48.5%, 39.4%, 23.4% and 25% respectively. There was a significantly higher IR observed in blastocysts with ICM grade A (p < 0.001) than those with B irrespective of their TE scores. The analysis of the interaction between the two characteristics confirmed the superiority of ICM over TE as a predictor of the outcome. The rank biserial correlation value for ICM was also greater compared to that of TE (0.11 vs 0.05). Conclusion This study confirms that the morphology of ICM of the blastocyst is a stronger predictor of implantation and clinical pregnancy than that of TE and can be utilized as a biomarker of viability.

Study question Will subendometrial injection of autologous platelet rich plasma (PRP) enhance the implantation by improving endometrial thickness (ET) and vascularity in frozen embryo transfers (FET)? Summary answer In this study it was observed that subendometrial injection of autologous PRP enhances implantation by improving ET and vascularity. What is known already Reports on evaluating effectiveness of injecting PRP hysteroscopically at the endomyometrial junction are limited. PRP has more effect on angiogenic growth cells as it contains high concentrations of vascular endothelial growth factor, epidermal growth factor, platelet derived growth factor, leukemia inhibiting factor, beta 3 integrin, transforming growth factor and cytokines which are essential for the endometrial proliferation. Previous reports suggest that these factors are inadequately expressed in a deficient endometrium and they are enhanced after PRP. Study design, size, duration From December 2019 to December 2021, 172 women with ET less than or equal to 7mm were included in the study and underwent PRP instillation. Patients with Asherman’s syndrome were excluded from the study. The endometrial vascularity zone as per Applebaum criteria was noted. Informed written consent obtained from all participants.The comparison of ET and vascularity before and after PRP was carried out by paired t test. This study was approved by Institutional ethical committee. Participants/materials, setting, methods 8 ml of autologous PRP was instilled at the junctional zone hysteroscopically from day 6-10 of menstrual cycle. After allowing 8 weeks for the endometrium to regenerate, ET and vascularity were measured and prepared for FET. The statistical significance was tested by comparing ET and vascularity before and after PRP using Paired T-test at 5% level of significance. FET was done for 109 women and the outcome was analysed. Main results and the role of chance Based on paired ‘t’test, it is concluded that there is statistically significant effective difference on ET after PRP at 0.05 significance level and vascularity following PRP at CI (-0.663± 0.11). T statistic = 1.653813 p value = 0.000282 and CI (-0.33±0.092),T statistic=1.653813, p value= 0.000254 respectively. Out of 172 women, ET increased in 130, decreased in 22 and remained the same in 20. Mean ET before and after PRP were 5.9mm and 6.6mm respectively which showed significant difference. Endometrial vascularity improved for 56 women decreased for 9 remained the same for 107. Of 172 women, 109 had underwent FET 44 showed positive BHCG value (40.3%) and 38 showed a clinical pregnancy rate (CPR) corresponding to 34.8%. Two others are awaited for the first scan Other two had blighted ovum, missed abortion respectively. CPR was observed to be 34.09% in the group with increased and 33.3% in the group with decreased and 44.4% in the group with no change in ET. Similarly the CPR was 30% in women with increased and 50% in those with decreased and 36% in the group with no change in vascularity. Limitations, reasons for caution The embryo quality and synchrony could have an effect on the pregnancy rate. It involves invasive procedure at a higher cost. It can cause infections and anaesthesia related complications. Wider implications of the findings we can assume that subendometrial injection of PRP is effective in improving the ET and vascularity and there by improve the pregnancy outcome. More studies are needed to confirm the effect of PRP in improving the endometrial thickness and vascularity and thereby implantation. Trial registration number N/A