Blastocyst conversion rate and ploidy in patients with structural rearrangements

Area of Science:

• Reproductive Medicine and Genetics
• Assisted Reproductive Technologies (ART)
• Embryology and Preimplantation Genetic Testing

Background:

• Preimplantation genetic testing (PGT) encompasses various techniques, including PGT for aneuploidy (PGT-A), PGT for monogenic disorders (PGT-M), and PGT for structural rearrangements (PGT-SR).
• Understanding the comparative efficiency and outcomes of different PGT methods is crucial for optimizing IVF treatment protocols.
• Previous studies have suggested potential differences in blastocyst development and embryo utilization among PGT subtypes.

Purpose of the Study:

• To compare blastocyst conversion rates and the availability of usable blastocysts between IVF cycles undergoing PGT-SR versus PGT-A (with or without PGT-M).
• To evaluate secondary outcomes, specifically pregnancy rates, implantation rates, and miscarriage rates across different PGT groups.
• To test the hypothesis that PGT-SR cycles result in poorer blastocyst development and fewer usable embryos compared to PGT-A cycles.

Main Methods:

• A retrospective cohort study was conducted, analyzing IVF cycles initiated between January 1, 2012, and March 30, 2020.
• Cycles included in the study involved intent for PGT-A, PGT-A with PGT-M, or PGT-SR, all utilizing trophectoderm biopsy on days 5 or 6 of development.
• Statistical adjustments were made for patient age, total mature oocytes, BMI, and intracytoplasmic sperm injection (ICSI) to account for confounding factors.

Main Results:

• A total of 902 cycles were analyzed: 607 PGT-A, 216 PGT-A&M, and 79 PGT-SR.
• Blastocyst conversion rates did not significantly differ between PGT-A (59.4%), PGT-A&M (69.7%), and PGT-SR (63.2%) groups after adjusted analysis.
• The proportion of usable blastocysts was significantly lower in PGT-SR (24.4%) and PGT-A&M (31.5%) groups compared to the PGT-A group (35.1%). Implantation, pregnancy, and miscarriage rates were equivalent across all groups.

Conclusions:

• Patients undergoing PGT-SR demonstrate comparable blastocyst development rates to those undergoing PGT-A.
• However, PGT-SR cycles yield a significantly lower number of usable blastocysts available for embryo transfer.
• Despite the reduced number of usable embryos, pregnancy outcomes are equivalent among PGT groups when a viable embryo is transferred, suggesting PGT-SR is effective when suitable embryos are available.