Repeating the PGS biopsy allows to recover euploid embryos and thus increase the pregnancy rate per cycle
Trophectoderm biopsy allows to test a larger number of embryo cells and to obtain a more reliable genetic diagnosis than with blastomere (embryo) biopsy at D + 3. Occasionally, Preimplantation Genetic Screening (PGS) may not yield conclusive results in some of the embryos tested. This particularly affects patients who have few embryos.
Dr. Monica Parriego of the Reproductive Medicine Service of the Department of Obstetrics, Gynaecology and Reproductive Medicine of Dexeus University Hospital thus conducted a study to determine whether thawing embryos with no PGS results for the purpose of a second biopsy+screening test is a safe and useful process that allows a conclusive diagnosis and to identify embryos that are free from genetic defects and suitable for transfer.
To this end, patients with embryos for which PGS failed to yield conclusive results were selected and given the option of having these embryos thawed in order to undergo a new biopsy to verify their viability. A total of 29 women agreed to participate in the study.
The survival rate of the thawed embryos was 86.2% (25/29). 72.4% (21/29) developed properly and successfully underwent a new biopsy. Blastocyst biopsy was performed using laser technology, and genetic analysis using aCGH.
After the second biopsy, 95.2% (20/21) of the blastocysts were successfully diagnosed and 65% (13/20) were euploid. To date, six re-biopsied blastocysts have been transferred to six patients, resulting in four pregnancies.
According to the authors, the study shows that blastocysts which do not yield conclusive results after the first test can be thawed and re-biopsied with a high success rate, allowing a definitive diagnosis. Rebiopsied embryos characterised as euploid retain a high potential for implantation, so that all patients with one or more embryos for which no conclusive diagnosis was obtained should be offered this option.
Communication : Inconclusive PGS results: go for a second biopsy!
Parriego M1, Coll L1, Boada M1, Vidal F2, Mateo S1, Coroleu B1, Veiga A1
1 Département d'obstétrique, de gynécologie et de médecine de la reproduction, hôpital universitaire Dexeus, Barcelone, Espagne
2 Département de biologie cellulaire, de physiologie et d'immunologie, UAB (Université autonome de Barcelone), Bellaterra, Espagne