P-403 Oocyte usage and disposition outcomes following oocyte cryopreservation
Authors: Johnston M , Fuscaldo G , Hunt S , Sutton L , Mills C , Rombauts L 
Published: June 2023

Abstract

Study question
What is the fate of cryopreserved oocytes?

Summary answer
Very few people return to use their cryopreserved oocytes in assisted reproduction and while some surplus oocytes are donated for reproduction, the majority are discarded.

What is known already
The number of oocyte cryopreservation cycles performed around the world dramatically outpaces the number of people who return to use their oocytes in assisted reproduction. This imbalance is leading to the rapid accumulation of oocytes in cryostorage. Previous studies have reported that many people intend to donate their surplus cryopreserved oocytes, and some commentators suggest that this may help relieve donor shortages. However, there have been no reports to date about what actually happens to surplus oocytes following oocyte cryopreservation.

Study design, size, duration
A retrospective cohort study was performed, analysing the outcomes for cryopreserved oocytes from 2012 - 2022.

Participants/materials, setting, methods
Data were collected from seven IVF clinics, located in Victoria, Australia. De-identified data were aggregated on the outcomes following oocyte cryopreservation, including duration of cryostorage, assisted reproduction involving thawed oocytes, and disposition outcomes of surplus oocytes.

Main results and the role of chance
Across the study period, the number of patients with oocytes in storage grew rapidly from 144 in 2012 to 2015 in 2022. Regarding the current status of oocytes in storage, in 2022, 73% of patients had had their oocytes in storage for &lt;5 years; 25% for 5 - 10 years, and 2% for ≥10 years. The majority of oocyte thaw cycles (600/645) involved oocytes frozen for &lt;5 years; of which 47% were frozen for &lt;6 months. Overall, the live birth rate from the total number of oocyte thaw cycles initiated was 12% (78/645), however, this varied depending on the reason oocytes were frozen. In comparison to the number of patients still with oocytes in storage, very few patients relinquished surplus oocytes across the study period (2015 vs 151, respectively). Of the 128 patients whose surplus oocytes were discarded, 32% had had their oocytes stored for &lt;5 years; 32% for 5-10 years, and 36% for &gt;10 years. Among patients who elected to donate their surplus oocytes (n = 23), all but four patients made this decision having had their oocytes in storage for &lt;5 years. Although a legal option in Australia, no oocytes were donated to research over the period analysed.

Limitations, reasons for caution
Data were collected from one fertility group based in one state of Australia, thus it may not be representative of wider trends seen across other clinics or states/territories. Further, specific state laws govern the management, storage, and use of surplus oocytes, which may influence the reported disposition outcomes.

Wider implications of the findings
Our findings suggest that cryopreserved oocytes are rarely used or donated, rather they are left in storage, often for long durations. To relieve some of the pressure this may create on cryostorage facilities, more attention is needed to better understand the experience of oocyte disposition and the barriers to donation.

Trial registration number
not applicable