Fertility Genetics acknowledged for review of new mosaic embryo transfer guidelines

Good practice recommendations were formulated that can be used by ART/PGT centres as a basis for their own policy with regards to the management of ‘mosaic’ embryos.The use of comprehensive chromosome screening technologies has provided a variety of data on the incidence of chromosomal mosaicism at the preimplantation stage of development and evidence is accumulating that clarifies the clinical outcomes after transfer of embryos with putative mosaic results, with regards to implantation, miscarriage and live birth rates, and neonatal outcomes. 

 

Recommendations are supported by data from the literature, a large survey evaluating current practice ( 239 centres) and published guidance documents.  

Eighty percent of centres that biopsy three or more cells report mosaicism, even though only 66.9% of all centres have validated their technology and only 61.8% of these have validated specifically for the calling of chro- mosomal mosaicism. The criteria for designating mosaicism, reporting and transfer policies vary significantly across the centres which emphasise the importance of genetic counselling before PGT-A and to understand mosaic results.