290 : Does Extending the Time Interval Between hCG Trigger and Oocyte Retrieval from 36 to 37 Hours Affect the Rate of Euploid Blastocysts?

Background and Aims: Data are lacking regarding the optimal time interval between human chorionic gonadotropin (hCG) administration and ovum pick-up (hCG-OPU interval), and its impact on blastocyst euploidy. Our aim was to compare the blastocyst euploidy rate between IVF cycles with hCG-OPU interval of 36 and 37 h. Method: In this historic cohort study, we reviewed all hCG-triggered, PGT-A, IVF cycles performed in a single clinic, between 2018 and 2022. Commencing in September 2021, clinicians gradually changed the hCG-OPU interval from 37 to 36 h. We compared the outcomes of cycles with hCG-OPU interval of 36 h (35.5-36.5) to 37 h (36.6-37.5). The primary outcome was the number of euploid embryos. Cycles with oocyte donation, and cycles utilized GnRH-agonist triggers or dual-triggers were excluded. Results: The euploidy rates were similar between the 36-h group (n=2,584) and 37 h group (n=5,575; 39.7% vs. 38.8%, respectively, p=0.42). Compared to the 36-h group, patients in the 37-h group were characterized by higher numbers of total oocytes collected (15.9±8.9 vs. 17.3±9.8, respectively, p