Chromosomally normal twin pregnancy following transfer of euploid and chaotic embryos, including those with trisomy 21

OBJECTIVE: We report a case of a chromosomally normal twin pregnancy following the transfer of one euploid female embryo and one chaotic male embryo with six aneuploidies, including trisomy 21, identified through preimplantation genetic testing for aneuploidy (PGT-A). CASE REPORT: A 35-year-old woman with unexplained recurrent implantation failure underwent IVF with PGT-A. Of three biopsied embryos, two were euploid female embryo, and one was chaotic male embryo with six aneuploid chromosomes. Following an unsuccessful single euploid frozen embryo transfer (FET), the couple opted for a double embryo transfer, including the chaotic embryo. We recommended a single euploid FET and advised against transferring the chaotic embryo without a re-biopsy. However, the couple declined a re-biopsy, fearing embryo damage. Despite thorough genetic counseling on risks like Down syndrome and twin pregnancy, they insisted on proceeding. To manage adenomyosis, a single-dose depot GnRH agonist was administered to achieve pituitary downregulation. An artificial cycle FET was initiated one month later. A dichorionic diamniotic twin pregnancy was confirmed by ultrasonography at 5, 7, 9, and 12 weeks of gestation, with chorionic villous sampling showing discordant fetal karyotypes (46,XY and 46,XX). At 35 weeks and 4 days, the patient delivered healthy twins (male: 3020 g, female: 2470 g), and umbilical cord blood analysis confirmed normal 46,XY and 46,XX karyotypes. CONCLUSION: This case highlights the potential viability of some chaotic embryos and emphasizes the need for further research to guide clinical decisions on their transfer.