P-285 Analysis, including morphokinetic data, of IVF/ICSI cycles with oocytes containing aggregates of smooth endoplasmic reticulum (SER)
Authors: Elebert R , Glover L , Bravo Martin R , O'Riordan S , Wingfield M 
Published: June 2023

Study question

Is there a difference in ART outcomes and morphokinetic parameters for SER+ and SER- cycles and oocytes?

Summary answer

Fertilisation and blastulation rates are lower in the SER+ group but no difference was seen in pregnancy or live birth rates.

What is known already

The SER is an organelle found in eukaryotic cells, including oocytes. SERs synthesize lipids and steroids, and store and metabolise calcium ions, needed for fertilization and early embryonic development. SERs can aggregate in the oocyte, forming an intracytoplasmic dimorphism, thought to interfere with reproductive outcomes. It is suggested that SER aggregates in an oocyte may negatively effect embryo development and implantation. Oocytes without SERs, but which arise from the same oocyte cohort as SER+ oocytes may also affect outcomes. Evidence around the safety and use of these SER+ and SER- oocytes is conflicting, with widespread variations in clinical practice.

Study design, size, duration

A retrospective review was conducted of all IVF/ICSI[MW1] cycles between January 2019 and December 2020 at Merrion Fertility Clinic, Dublin. Cycles containing SER+ oocytes were identified, and their outcomes were compared with those of a matched control group of SER- cycles. Within the SER+ group, results were compared for SER+ and SER- oocytes within the same cohort.

Participants/materials, setting, methods

Once participants had been identified, a chart review was undertaken noting demographics, IVF protocol used, duration of stimulation, ART and neonatal outcomes and morphokinetic parameters in the embryoscope. Statistical analysis was performed using PRISM.

Main results and the role of chance

There were 77 SER+ cycles with a total of 135 SER+ oocytes and 645 SER- oocytes, accounting for 8% of total cycles for the study period. These were matched to 64 control cycles with 528 SER- oocytes. 12 embryo transfers occured using blastocysts derived from SER+ oocytes. SER+ cycles had a higher mean oocyte number than controls (9.3 vs 7.3) and 92% of oocytes were mature compared to 88% of the control group. Fertilisation rates were significantly lower in the study group (60% SER+cycle; 68% in SER-cycle), related to the SER+ oocytes in that cohort. Good/top quality blastocyst rates differed (SER+ cycle 28%, SER- cycle 36%) but pregnancy(SER+ cycle 53%, SER- cycle 51%) and livebirth (SER+31%, SER- 32% ) rates were similar, even when blastocysts derived from SER+ oocytes were transferred.

5 morphokinetic variables were studied – time to 2-cell (t2), 3 cell (t3) 4 cell (t4), 5 cell (t5) and time to blastulation (tB). T5 appears to be shorter in embryos derived from SER+ oocytes than in controls, with the other parameters being comparable. In terms of neonatal outcomes there were no congenital malformations reported in the SER+ groups and one case of upper limb amelia in the control group.

Limitations, reasons for caution

This study is limited by its retrospective nature. We only have embryoscope data on 46 out of 77 patients with SERs, limiting numbers. Embryos transferred which derived from SER+ve oocytes were limited by the clinic policy to only transfer these embryos if no other embryos available. PGT was not performed.

Wider implications of the findings

This preliminary study shows that, while SER+ cycles have lower fertilisation rates than SER- cycles, pregnancy rates and live birth rates are comparable. Neonatal outcomes are reassuring. Initial analysis of morphokinetic data shows little effect. Larger numbers and further analysis are needed to fully understand the importance of these aggregates.

Trial registration number

n/a