Preimplantation Genetic Testing for Chromosomal Structural Rearrangements - What Should We Expect?
Abstract
Introduction: Patients with a known chromosomal structural rearrangement, can utilize preimplantation genetic testing for aneuploidy (PGT-A) and structural rearrangements (PGT-SR) to transfer a chromosomally balanced embryo to mitigate infertility, miscarriage, and recurrent pregnancy loss due to chromosomal imbalances. This study aimed to determine the time and number of oocyte retrievals needed to achieve a live birth for patients undergoing combined PGT-A/PGT-SR.
Methods: We performed an IRB approved retrospective data query of a large, national private practice for patients utilizing PGT-A/PGT-SR from 2013 to 2022. The primary outcomes were number of oocyte retrievals to live birth and time (months) from ovarian stimulation start to frozen embryo transfer (FET), clinical pregnancy (CP), and live birth (LB) following a euploid, chromosomally balanced FET. Secondary outcomes included the number of FET cycles to LB and proportion of patients that did not achieve FET, CP, or LB. Kaplan-Meier curves were used to calculate median time to FET, CP, and LB.
Results: There were 68 patients who underwent combined PGT-A/PGT-SR with a mean age of 33.8 and AMH of 2.7 (1.5, 4). For all included cycles, the median number of embryos biopsied was 5. Of these, 1 was both euploid and structurally balanced. In order to achieve a LB, the median number of oocyte retrievals was 2 (2,3) and transfers was 1 (1,2). For patients who underwent oocyte retrieval, 23.8% did not have a transfer within 1 year and 7.4% (5 of 68) ultimately did not have an unaffected, euploid embryo to transfer. At two years, the live birth rate was 65.4% (50.3, 75.9). Overall, the miscarriage rate after a euploid, structurally balanced transfer was 11.5%. The median times to FET, CP, and LB were 3.1, 7.0, and 15.9 months, respectively.
Conclusion: In a group of patients with normal ovarian reserve pursuing combined PGT-A and PGT-SR, there was a median requirement of 2 oocyte retrievals and 1 transfer of an unaffected, euploid embryo to achieve LB. The median time to LB was 15.9 months with the caveat that 34.6% of patients had not achieved a LB within 2 years of cycle start. Despite excellent ovarian reserve, the timeline to achieve a LB may extend over years. This study characterizes the treatment history for patients utilizing PGT-SR and will contribute to improved patient counseling and managing expectations prior to undergoing treatment.