Dados do Trabalho

Title

Successful Pregnancy Achievement after Transfer of Euploid Embryo Originating from Oocyte Fertilized with 3 Pronuclei (3PN)

Objective

In this case report, the successful pregnancy was accomplished following the transfer of a chromosomally normal embryo resulting from fertilization of an oocyte with three pronuclei (3PN), which underwent comprehensive ploidy analysis prior to implantation.

Methods

In this study, a 40-year-old patient underwent in vitro fertilization (IVF) using donated oocytes and donor sperm, and 12 mature oocytes were allocated for the treatment. Fertilization assessment occurred 19 hours after intracytoplasmic sperm injection (ICSI), and subsequent embryo development was individually monitored in continuous culture medium. Assessments were conducted on day 3, with assisted hatching, and on days 5, 6, and 7 at the blastocyst stage. Blastocysts that reached the expanded blastocyst stage underwent biopsy followed by freezing, and the biopsied cells were sent to the genetics laboratory for pre-implantation genetic testing for aneuploidies (PGT-A) and ploidy analysis for the potential transfer, thereby augmenting the likelihood of a successful pregnancy outcome.

Results

Among the 12 injected oocytes, all showed signs of fertilization, with 8 of them having 2 pronuclei, 1 with 1 pronucleus, 1 with 3 pronuclei, and 2 with 2 polar bodies. On the third development day, the 3PN-derived embryo displayed 14 cells with <10% fragmentation. On the fifth day of development, four embryos reached blastocyst level for biopsy, including one originating from a 3PN fertilized oocyte. This embryo received a 5AB grading according to Gardner's criteria, indicating the best morphological classification compared to other blastocysts. Genetic analysis was performed on samples from two blastocysts, confirming their euploid status. Notably, one of the euploid embryos was derived from a 3PN oocyte, and genetic analysis revealed it to be a diploid embryo with a mitoscore of 19.01 The decision to transfer this specific euploid embryo was based on its superior quality compared to the others. Subsequently, the 3PN-derived euploid embryo underwent freezing and was transferred to a surrogate uterus in the following month. The following month, the embryo was thawed and transferred to a surrogate uterus, given the patient's history of pregnancies with early growth restriction, leading to fetal demise due to uterine conditions. Two hours before the transfer, the embryo was thawed and was fully expanded at the time of transfer. Monitoring the patient's hormone levels through beta-HCG measurements revealed a consistent increase, with 349.65 mIU/mL at nine days post-transfer, 916.70 mIU/mL on day 11, and 2,237.06 mIU/mL on day 14. Ultrasound examinations confirmed the pregnancy at 6 weeks and 12 weeks, showing a healthy, viable fetus with normal development. At 12 weeks, the patient underwent a morphological ultrasound, revealing a single, viable fetus with a crown-rump length of 5.4 cm, a nuchal translucency of 1mm, and a visible nasal bone. Currently, at 15 weeks of gestation, the patient is undergoing uncomplicated prenatal follow-up.

Conclusion

Further research and larger studies are warranted to validate the findings of this case report and to elucidate the potential implications of 3PN-derived euploid embryos on overall IVF success rates and reproductive outcomes.

Keywords

Euploid embryo, 3 Pronuclei (3PN), Genetic analysis