The Impact of Biopsy on Human Embryo Developmental Potential during Preimplantation Genetic Diagnosis

Abstract

Preimplantation Genetic Diagnosis and Screening (PGD/PGS) for monogenic diseases and/or numerical/structural chromosomal abnormalities is a tool for embryo testing aimed at identifying nonaffected and/or euploid embryos in a cohort produced during an IVF cycle. A critical aspect of this technology is the potential detrimental effect that the biopsy itself can have upon the embryo. Different embryo biopsy strategies have been proposed. Cleavage stage blastomere biopsy still represents the most commonly used method in Europe nowadays, although this approach has been shown to have a negative impact on embryo viability and implantation potential. Polar body biopsy has been proposed as an alternative to embryo biopsy especially for aneuploidy testing. However, to date no sufficiently powered study has clarified the impact of this procedure on embryo reproductive competence. Blastocyst stage biopsy represents nowadays the safest approach not to impact embryo implantation potential. For this reason, as well as for the evidences of a higher consistency of the molecular analysis when performed on trophectoderm cells, blastocyst biopsy implementation is gradually increasing worldwide. The aim of this review is to present the evidences published to date on the impact of the biopsy at different stages of preimplantation development upon human embryos reproductive potential.

Blastomere biopsy for PGD delays embryo compaction and blastulation: a time-lapse microscopic analysis

“…It may demonstrate the embryos' difficulty to overcome the interference of a blastomere biopsy. An interesting explanation may be that embryos at this stage of preimplantation development are relatively fragile since embryonic genome activation and cell differentiation processes have not yet occurred [8]. Thus, downstream developmental processes can be irreparably compromised by removing a cell from the embryo.…”

“…It was recently suggested that a trophectoderm biopsy from a day 5 blastocyst has a less harmful effect on further embryonic development compared to blastomere biopsy of day 3 cleavage-stage embryos [3,8,11,44,45]. Scott et al identified blastocyst-stage biopsy as a procedure that does not affect embryo viability and implantation potential as opposed to blastomere biopsy [4].…”

“…In addition, the fact that frozen embryo transfers are performed in the absence of ovarian stimulation (lowering the risk for ovarian hyperstimulation syndrome and multiple pregnancies) has led to a shift from day 3 cleavagestage biopsies to day 5 blastocyst biopsies. Nevertheless, cleavage-stage biopsy is still the most commonly used strategy for PGD, at least in Europe, possibly under the perception that it is less operator dependent and more reproducible [8,9].…”

“…2009 and 2010, while TE biopsy accounted for less than 1 % [6]. The same data referring to years 2012-2013 revealed a shift toward trophectoderm biopsies for PGD as cleavagestage biopsies decreased to approximately 75 % of all embryo biopsy cycles [reviewed by [8]]. Despite the notable shift, according to the latest ESHRE PGD Consortium data collection XIII published on 2015, cleavage-stage biopsy is currently still the preferential stage/method for biopsy [9].…”

“…Polar body biopsy has been proposed as an alternative to embryo biopsy, especially for aneuploidy testing. However, no sufficiently powered study has thus far clarified the impact of this procedure on embryo reproductive competence, and it is not a common practice (approximately 2 % of embryo biopsies) [8].…”