What proportion of embryos should be considered for transfer following a mosaic diagnosis? A study of 115 clinics from a central diagnostic laboratory

Purpose The aim of this study is to identify what proportion of mosaic embryo diagnoses should be considered for transfer, and thereby assess the impact on patient cases. Methods We categorised mosaic embryos into 3 groups; high, medium and low priority for transfer based on the percentage of biopsy sample being aneuploid and the chromosomes involved.The categories were applied to those patients that had no euploid embryo diagnoses but 1 or more mosaic embryos identified as mosaic available after PGT-A. Results In total, 6614 PGT-A cases from 115 clinics and a single diagnostic laboratory were reviewed. Further, 1384 [20.9%] cases only had aneuploid embryos, 4538 [68.6%] cases had one or more euploid embryos and 692 [10.5%] cases had no euploid and one or more mosaic embryo.The mosaic embryos in the no euploid, one or more mosaic group, when reviewed using priorities, resulted in: 111 [1.7%] of cases having at least one high priority mosaic available. 184 [2.8%] of cases having no high priority but at least one medium priority mosaic available. 397 [6.0%] of cases only having low priority mosaic embryos available. Conclusion Based on this data, embryos identified as mosaic will only be considered for transfer in the first instance for around 4.5% (when taking high and medium priority and excluding low priority cases) of all PGT-A cases.

Automated summary

The purpose of this study is to determine the proportion of mosaic embryos that can be considered for transfer and evaluate their impact on patient cases. Mosaic embryos were categorized into high, medium, and low priority groups based on the percentage of aneuploidy in the biopsy sample and the chromosomes involved. The results showed that only around 4.5% of all PGT-A cases would consider mosaic embryos for transfer, when considering high and medium priority and excluding low priority cases.