Number of embryos to be biopsied is a strong predictive indicator for a successful preimplantation genetic diagnosis outcome in translocation cases

Abstract

The objective of this study was to analyse if the pregnancy rate and cycle outcome of translocation carriers affected by the number of embryos biopsied for preimplantation genetic diagnosis (PGD)? Transfer and pregnancy rates of patients undergoing PGD for both Robertsonian and reciprocal translocations were retrospectively analysed from August 2010 to December 2012 in Bahceci Assisted Reproductive Technology Centres. Fifty cycles of PGD was performed for 45 couples carrying Robertsonian and reciprocal translocations by multicolour fluorescent in situ hybridisation (FISH) on day 3 post fertilisation. The genetic as well as cycle outcomes of PGD cases were examined and the successful pregnancies were followed up. The chance of finding a balanced embryo is considerably higher when nine or more embryos (group 1, 408 embryos) were biopsied and analysed in PGD cycles. When eight or less biopsied embryos were analysed (group 2, 123 embryos), the chance of finding a transferable embryo after PGD was 32% compared to77% in group 1. Therefore, the cancellation rate in group 2 is significantly higher than group 1. Furthermore, once a suitable embryo is found, the pregnancy rates were slightly higher in group 1 (38%) compared to the group 2 (33%) per embryo transfer. This study shows that the number of embryos analysed for translocations in PGD plays an important role in finding a balanced embryo and successful cycle outcome. If there are less than nine embryos biopsied for PGD, the likelihood of finding a balanced embryo is considerably reduced and the cycle cancellation risk is high. In these patients, performing multiple cycles of in vitro fertilisation and pooling the embryos by current cryopreservation techniques before PGD analysis can be advised.