Number of embryos biopsied as a predictive indicator for the outcome of preimplantation genetic diagnosis by fluorescence in situ hybridisation in translocation cases

Abstract

This study aimed to investigate the optimum number of embryos to be biopsied in order to increase the likelihood of obtaining a balanced/normal embryo following preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridisation (FISH) for translocation carriers. Patients with low number of fertilised oocytes (≤5) or low number of embryos available for PGD (<7) underwent multiple hormonal stimulation cycles and their embryos from each cycle were vitrified and accumulated to obtain at least three embryos for PGD. Fifty-seven PGD cycles were performed for translocation carriers by FISH on day 3 of embryo development. PGD and pregnancy outcomes were examined according to the number of embryos biopsied. The cancellation rates of embryo transfer for the reciprocal translocation carriers were 40% when more than eight embryos were biopsied and it was as high as 78% when low number of embryos (less than nine) were biopsied. For Robertsonian translocation carriers, when more than eight embryos were biopsied, there were no embryo transfer cancellations. This study showed that when there are more than nine embryos biopsied for PGD, the likelihood of obtaining a balanced embryo and positive pregnancy outcome is significantly higher (P < 0.05) in such the overall pregnancy rate was 63% for reciprocal and 86% for Robertsonian carriers. This was reduced to only 7% for reciprocal and 14% for Robertsonian translocation carriers when less than nine embryos were biopsied. One of the limitations of this study was that the analysis was performed by FISH and more studies should investigate the outcomes of embryo accumulation following comprehensive chromosome analysis.

No Additional Benefit of Eliminating Transfer Cancellations Using Cleavage-stage Transfers for Patients With Few Zygotes: A Retrospective Cohort Study

“…Recent studies support this conclusion, as clinical pregnancy and live birth rates have been shown to increase according to the number of eggs retrieved [20] and oocytes fertilized [21]. Consequently, the probability of nding at least one euploid embryo increases with the number of oocytes retrieved [22] and embryos biopsied [23]. The blastocyst cohort size is also associated with at least one euploid embryo being found [24].…”

Chromosomal Abnormalities in Preimplantation Embryos and Detection Strategies in PGD and PGS

“…In the past, one of the main problems of performing blastocyst biopsy was the limited time allowed for the diagnosis since the embryonic cells are either biopsied on day 5 or on day 6 for the slow developing embryos. With the use of vitrification, high embryo survival rates were reported [77][78][79][80], and many centers have opted performing PGS at blastocyst stage [81]. Furthermore, vitrifying embryos provide chance of an embryo transfer during an unstimulated cycle that was shown to result in high pregnancy rates [82][83][84].…”