P-525 PGT-A with embryo pooling: does it result in a higher yield of euploid embryos and better clinical pregnancy outcomes?

Abstract Study question Does PGT-A with embryo pooling result in a higher yield of euploid embryos and better clinical pregnancy outcomes compared to PGT-A done after one cycle? Summary answer There is no evidence to support that embryo pooling for PGT-A purposes is favorable in preference to PGT-A after one cycle. What is known already PGT-A has been the method of choice that is thought to optimize embryo selection and enhance clinical outcomes. However, the number of embryos available for biopsy can be a source of limitation, as the yield of euploid embryos suitable for transfer can be affected when lower number of embryos are available for screening. A protocol that is suggested to overcome this limitation is to undergo multiple IVF/ICSI cycles with blastocyst biopsy and embryo pooling, then proceed with PGT-A screening once a sufficient number of biopsied embryos is attained. Study design, size, duration This is a retrospective study that included ICSI cycles from June 2019 to December 2021, involving 157 patients (average maternal age 36.4) that underwent PGT-A after one ICSI cycle (group A), and 79 patients (average maternal age 35.6 ) that underwent PGT-A after embryo pooling from more than one ICSI cycle (Group B). Patients in group B underwent pooling due to cost implications on the number of embryos to screen. Participants/materials, setting, methods A total of 843 embryos were biopsied and screened for group A, and 536 were biopsied and screened for group B. Following PGT-A screening, a number of frozen embryo transfers (FET) were conducted (120, 67 respectively). Investigations included: number of embryos available for biopsy, number of euploid embryos and clinical pregnancy outcomes after FET. Statistical analysis was calculated (P < 0.05). Main results and the role of chance Patients in group A proceeded with PGT-A after only one ICSI cycle, while in group B patients underwent 2.3 cycles on average. The average number of embryos suitable for biopsy was 5.4, and 6.9 per patient respectively. The rate of euploid embryos was 42.1% and 43.8%, and the average number of euploid embryos per patient was 5.4 and 6.5 respectively. A total of 144 embryos were transferred in group A with an average of 1.2 embryos per patient. Clinical pregnancy rate (CPR) was 60%, implantation rate was 54.9% and live birth rate (LBR) was 35.8%. In Group B a total of 67 embryos were transferred with an average of 1.1 embryos per patient. Clinical pregnancy rate (CPR) was 67.7%, implantation rate was 68.7% and live birth rate (LBR) was 40%. No significant difference was observed between both groups for clinical outcomes (P > 0.05). Limitations, reasons for caution This study is retrospective and small in size. Data on live birth rate requires further follow up as a number of patients are still in ongoing pregnancies. A larger data set study is needed to support conclusion. Wider implications of the findings Results from this study does not support the adoption of a pooling strategy for patients undergoing PGT-A. Although the number of embryos available for biopsy may increase slightly, the yield of euploid embryos is not significantly increased and the clinical pregnancy rate is not enhanced. Trial registration number not applicable