How many couples decide to transfer a mosaic embryo?
The existence of mosaic embryos has been known for decades. However, only recently new technologies made it possible to detect this trait through the Preimplantation Genetic Diagnosis for cycles with risk of aneuploidies (PGD-A). It is known that this type of embryo can lead to the birth of healthy babies, but the potential risk of affectations cannot be ruled out.
Most of the studies conducted on this topic have focused on the clinical results after the transfer of mosaic embryos, but very few have analysed the decision of the parents and / or future parents about this situation in cases in which transferring a mosaic embryo is their only option. The embryologist Dr Monica Parriego, head of the Laboratory of Preimplantation Genetic Diagnosis of the Dexeus Mujer, has carried out a retrospective study on a total of 383 PGD-A cycles, carried out between October 2017 and December 2018. 24% of the total of the cycles (95/383) presented at least one embryo diagnosed as a mosaic, and in 4.4% (17/383) the only possibility of transfer was an embryo that presented this trait. Of the cycles that in principle had euploid embryos, 2.1% (6/288) failed and had to face the decision to transfer a mosaic embryo. In the end, there were 23 patients who faced this decision. The majority (91.3%) accepted genetic counselling. Only 2 rejected the option from the beginning and opted for a new cycle. Of the rest, 26.1% (6/23) agreed to carry out the transfer, 39.1% (9/23) chose to keep them cryogenized and try a new cycle, and 34.8% (8/23) decided to discard the mosaic embryos.
M. Parriego, L. Coll, G. Palacios, M. Boada, B. Coroleu, A. Veiga.
Dexeus University Hospital, Department of Gynaecology- Obstetrics and Reproduction, Barcelona, Spain.