"Survival rates after vitrification of oocytes obtained after luteal phase vs follicular phase ovarian stimulation"

Abstract Study question Do the oocytes retrieved after luteal phase ovarian stimulation (OS) have the same survival rate as those retrieved after follicular phase (OS)? Summary answer Oocyte survival rate after vitrification is similar in oocytes retrieved in a follicular phase OS compared to those in luteal phase. What is known already Oocytes retrieved in luteal phase have recently captured scientific interest as dual stimulation is gaining popularity. Oocytes obtained in luteal phase OS added to those obtained in follicular phase shorten time to pregnancy per intention to treat in poor responders. Embryos obtained with these oocytes show similar ploidy rates, as well as clinical outcomes. Study design, size, duration We analyzed data from a randomized, non-inferiority Duo Stim Preimplantation Genetic Testing for aneuploidies (PGT-A) trial performed from 2017 to 2021 in women >38 years old. Only cycles with at least one oocyte retrieved in both follicular and luteal were included. We compared survival rates from oocytes obtained in after follicular phase OS (n = 154 oocytes) versus luteal phase OS (n = 201 oocytes) within the same patient. Participants/materials, setting, methods A subtotal of 38 patients were included who underwent 2, 3, or 4 OS cycles to accumulate oocytes for subsequent ICSI with PGT-A. After retrieval and decumulation, oocyte vitrification was performed with Kitazato vitrification protocol (Kitazato, Japan) and Cryotop device, same as subsequent thawing. Main results and the role of chance Mean of age in the selected patients was 39,7 years. In total, 195 cumulus-oocyte complexes were retrieved after follicular phase OS vs 245 in luteal phase. From this group of oocytes, 145/195 were mature (78.97%) vs 201/245 (82.04%), respectively. No statistically significant differences were observed in survival rate whether oocytes came from a follicular phase OS 81.16 % (125/154) versus luteal phase 87.06% (175/201) (p = 0.3312). Our results confirm that survival rate of oocyte obtained in a luteal phase OS is comparable to conventional follicular phase OS, validating oocyte accumulation strategy in a Duo Stim protocol. Limitations, reasons for caution The limited sample size was due to the nature of the randomized, controlled trial. Our results need to be replicated in larger series for validation. Wider implications of the findings Luteal phase OS oocytes showed similar survival rates after thawing than conventional OS cycles, opening a new venue for oocyte vitrification in oncological patients or poor responders accumulating oocytes. This approach might be of interest as well in patients or countries where ethical/legal limitations may limit embryo accumulation. Trial registration number not applicable