Planned oocyte cryopreservation: the state of the ART.

The objective of this review is to provide an update on planned oocyte cryopreservation. This fertility preservation method increases reproductive autonomy by allowing women to postpone childbearing whilst maintaining the option of having a biological child. Oocyte cryopreservation is no longer considered experimental, and its use has increased dramatically in recent years as more women delay childbearing for personal, professional and financial reasons. Despite increased usage, most patients who have undergone oocyte cryopreservation have not yet warmed their oocytes. Most women who cryopreserve oocytes wait years to use them, and many never use them. Studies have demonstrated that oocyte cryopreservation results in live birth rates comparable with IVF treatment using fresh oocytes, and does not pose additional safety risks to offspring. Based on current evidence, cryopreserving ≥20 mature oocytes at <38 years of age provides a 70% chance of one live birth. However, larger studies from a variety of geographic locations and centre types are needed to confirm these findings. Additional research is also needed to determine the recommended age for oocyte cryopreservation, recommended number of oocytes to cryopreserve, return and discard/non-use rates, cost-effectiveness, and how best to distribute accurate and up-to-date information to potential patients.

Blinded rebiopsy and analysis of noneuploid embryos with 2 distinct preimplantation genetic testing platforms for aneuploidy.

OBJECTIVE: To determine how often a noneuploid result from a single trophectoderm (TE) biopsy tested with the next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) is concordant with rebiopsies tested with a single-nucleotide polymorphism (SNP) array-based PGT-A platform. DESIGN: Blinded prospective cohort study. SETTING: University-affiliated fertility center. PATIENT(S): One hundred blastocysts were chosen from donated samples; on TE biopsy with NGS-based PGT-A, 40 had at least one whole chromosome full copy number aneuploidy alone, 20 had a single whole chromosome intermediate copy number ("whole chromosome mosaic"), 20 had a single full segmental aneuploidy (segA), and 20 had a single segmental intermediate copy number ("segmental mosaic"). INTERVENTIONS: Four rebiopsies were collected from each embryo: 3 TE biopsies and the remaining embryo. Each rebiopsy was randomized, blinded, and assessed with an SNP array-based PGT-A platform that combines copy number and allele ratio analyses, without mosaicism reporting. MAIN OUTCOME MEASURE(S): Concordance between the NGS result and rebiopsy results and within each embryo's blinded rebiopsy results. RESULT(S): Next-generation sequencing-diagnosed whole chromosome aneuploidy (WCA) was reconfirmed in 95% (95% confidence interval [CI], 83%-99%) of embryos; 2 embryos with NGS-diagnosed WCA were called euploid on all conclusive rebiopsies. Among embryos with NGS-diagnosed whole chromosome mosaicism, 35% (95% CI, 15%-59%) were called euploid and 15% (95% CI, 3%-38%) were called whole chromosome aneuploid on all conclusive rebiopsies. A total of 30% (95% CI, 12%-54%) of embryos with NGS-diagnosed segA and 65% (95% CI, 41%-85%) of embryos with NGS-diagnosed segmental mosaicism were called euploid on all conclusive rebiopsies. In total, 13% (95% CI, 6%-25%) of embryos with NGS-diagnosed full copy number aneuploidy and 50% (95% CI, 34%-66%) of embryos with NGS-diagnosed mosaicism had uniformly euploid SNP results. Conversely, all embryos with at least one noneuploid SNP result (n = 72) either had SNP-diagnosed aneuploidy on another rebiopsy from the same embryo or NGS-diagnosed aneuploidy/mosaicism involving the same chromosome. CONCLUSION(S): Next-generation sequencing-diagnosed WCA is highly concordant with rebiopsies tested with an SNP array-based PGT-A; however, whole chromosome mosaicism, segA, and segmental mosaicism are less concordant, reinforcing that embryos with these results may have reproductive potential and be suitable for transfer.

Fifteen years of autologous oocyte thaw outcomes from a large university-based fertility center.

OBJECTIVE: To review the outcomes of patients who underwent autologous oocyte thaw after planned oocyte cryopreservation. DESIGN: Retrospective cohort study. SETTING: Large urban university-affiliated fertility center. PATIENT(S): All patients who underwent ≥1 autologous oocyte thaw before December 31, 2020. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The primary outcome was the final live birth rate (FLBR) per patient, and only patients who had a live birth (LB) or consumed all remaining inventory (cryopreserved oocytes and resultant euploid/untested/no result embryos) were included. The secondary outcomes were laboratory outcomes and LB rates per transfer. RESULT(S): A total of 543 patients underwent 800 oocyte cryopreservations, 605 thaws, and 436 transfers. The median age at the first cryopreservation was 38.3 years. The median time between the first cryopreservation and thaw was 4.2 years. The median numbers of oocytes and metaphase II oocytes (M2s) thawed per patient were 14 and 12, respectively. Overall survival of all thawed oocytes was 79%. Of all patients, 61% underwent ≥1 transfer. Among euploid (n = 262) and nonbiopsied (n = 158) transfers, the LB rates per transfer were 55% and 31%, respectively. The FLBR per patient was 39%. Age at cryopreservation and the number of M2s thawed were predictive of LB; the FLBR per patient was >50% for patients aged <38 years at cryopreservation or who thawed ≥20 M2s. A total of 173 patients (32%) have remaining inventory. CONCLUSION(S): Autologous oocyte thaw resulted in a 39% FLBR per patient, which is comparable with age-matched in vitro fertilization outcomes. Studies with larger cohorts are necessary.