Previously aneuploidy embryo transfer was one of the leading causes of IVF cycle failure due to unsuccessful implantation. Raising of maternal age has a direct link with the increasing rate of embryonic aneuploidy. But IVF technology advancement is continuous which introduces different advanced expertise like extended embryo culture, vitrification and trophectoderm biopsy. Moreover, IVF collaborates with advanced, noble technology in pre-implantation genetic screening and next-generation sequencing. This collaboration of technologies improves the selective transfer of euploid blastocysts and related pregnancy rates by reducing the rate of error and implantation.
Strategies of euploid embryo transfer in IVF
Currently, two euploid embryos transfer strategies are followed in clinical practice, which includes freeze-all (vitrified) or fresh embryos for the first embryos transfer. But there is a confusion among clinicians which method (frozen or fresh) is best for embryo transfer strategy.
In the freeze-all strategy, cryopreserve all embryos after the conduction of biopsy and post genetic screening results. On the fifth or sixth day, frozen embryo transfer is conducted. Whereas in case of fresh embryo transfer, post genetic screening result is obtained through biopsy of expanded blastocysts. On the sixth day, a fresh embryo transfer of euploid embryos is conducted. However, slow-growing embryos in case of fresh transfer may freeze after the conduction of biopsy for future use.
Comparison between freeze and fresh euploid transfer strategy
The freeze and fresh euploid have their specific advantages and challenges. Evidential support reported that the pregnancy rate is higher in the case of a non-stimulated cycle conducted for vitrified/warmed embryo transfer compared with the stimulated cycle of fresh transfer. Preterm delivery and low birth weight incidence rate are higher in case of fresh transfer than frozen transfer. But the requirement of high survival rates in embryo vitrification methods is one of the challenges of frozen embryo transfer. Even though the application of the latest medical advancement, the risk of embryo damage is 3% in the application of vitrification or the warming process.
The advantages of fresh transfer include more affordable than frozen embryo transfer. The fresh transfer requires the neglected amount of additional medicine and allows the immediate transfer. Day 6 fresh embryo transfer approach requires expanded blastocysts along with at least one of these embryos should be euploid, This reduces the success rate of embryo transfer outcome.
Clinical research based evidential support
A randomized clinical trial conducted to compare the fresh vs vitrified euploid embryo transfer in IVF conducted through pre-implantation genetic screening. This research was conducted in 2017 in a private assisted reproductive center. In this research study, 179 patients had participated, who undergone IVF treatment using preimplantation genetic screening. The patients had divided into two groups at the time of hCG administration. Patients were either a freeze-all cycle or a fresh day 6 embryo transfer during the stimulated cycle. The research findings were evaluated through implantation rates, ongoing pregnancy rates, and live birth rate per embryo transfer in the primary transfer cycle. The obtained result showed that the implantation rate is higher in the frozen group (75%) than the fresh group (67%). But the difference was not very significant. But pregnancy and live birth rates are significantly higher in the frozen group compared with the fresh group. The pregnancy rate of frozen group vs fresh group was 80% vs 61%, whereas live birth rates are 77% vs 59%. From this study result, the investigators of this research had concluded that the freeze-all option is preferable in case of euploid embryos transfer.