Re-Biopsied PGS Embryos Yield Actionable Results.
Presenter: Dana Neitzel
OBJECTIVE: To determine the likelihood of obtaining preimplantation genetic screening (PGS) results from trophectoderm re-biopsies. view more
OBJECTIVE: To determine the likelihood of obtaining preimplantation genetic screening (PGS) results from trophectoderm re-biopsies.
DESIGN: Failure to obtain an actionable result (no-result) is one limitation of PGS and appears to be independent of the stage of embryo development or testing platform used. Some failures may be attributed to the number of cells tubed, embryo quality, and even biopsy and/or tubing technique. Other causes may be degradation post-biopsy, storage and shipping, or technical amplification failure. Even under optimal conditions, embryo biopsies with no interpretable result continue to represent a challenge in a minority of cases. An alternative to discarding or blindly transferring no-result PGS embryos is to re-biopsy for repeat analysis. There is a common misconception that most no-result biopsies occur on poor quality embryos that are unlikely to be suitable for transfer and unlikely to yield a result on re-biopsy. Here we report our experience with PGS re-biopsies yielding actionable results.
MATERIALS AND METHODS: 206 trophectoderm biopsies from previous no-result embryos from 39 IVF centers were submitted for re-analysis. Samples were analyzed using a targeted next-generation sequencing-based assay validated for whole chromosome and segmental (>10MB) aneuploidy detection. Variables such as biopsy technician, biopsy stage, and percent aneuploidy were analyzed.
RESULTS: Results were obtained in >97% of all re-biopsies (200 of 206). There was no significant difference in the ability to obtain results when broken down by biopsy day. Results were obtained in 96.9% of day 5 re-biopsies (156 of 161), 97.7% of day 6 re-biopsies (42 of 43), and 100% of day 7 re-biopsies (2 of 2).
Consistent with published euploidy rates in PGS, 55% (110) of re-biopsies with results were euploid. Euploid rates ranged from 45% in day 6 embryos to 57% in day 5 embryos and 100% in the two day 7 re-biopsied embryos. Of the 90 aneuploidies, excluding sex chromosome abnormalities, 7 were potentially compatible with life (3 T21, 2 T18, 2 T13).
Over half the time the same embryologist performed both the initial biopsy and re-biopsy (118 of 196; 60.2%), although often this information was not provided.
CONCLUSIONS: An inherent limitation of all PGS technologies is no-result embryos. In these situations, patients must decide to blindly transfer, discard, or to re-biopsy. While it is acknowledged that re-biopsy creates additional work and expense for the clinic, and may extend the time to transfer thus complicating the patient’s decision, greater than 97% of re-biopsies yielded actionable results. The effort may be worth the benefit of identifying a euploid embryo to transfer thereby decreasing the chance of miscarriage or delivering a child with a chromosome disorder. Given that >50% of re-biopsied no-result embryos are euploid, it is important that no-result embryos be identified as such, rather than be resulted as abnormal, to avoid discarding embryos that can lead to healthy babies.