Abstract
BackgroundWith improvements in in vitro culture techniques there has been a steady shift in practice to transfer embryos at the blastocyst stage (post fertilization day (p.f.d.) 5–7), when embryos reach the endometrial cavity during natural conception. For patients with > 5 zygotes on day 1 of embryo development, fresh blastocyst embryo transfer (ET) increases live birth rates when compared to cleavage stage (p.f.d. 3) transfer. In poorer prognosis patients (≤ 5 zygotes) cleavage stage ET is commonly performed to reduce the risk of cycle cancellation if no embryo survives to the blastocyst stage. However, there is a dearth of randomized controlled trial (RCT) data demonstrating improved live birth rates per cycle for cleavage vs blastocyst stage ET in this subgroup of patients. The hypothesis of the PRECiSE (PooR Embryo Yield Cleavage Stage Versus blaStocyst Embryo Transfer) trial is that blastocyst ET is not inferior to cleavage stage ET with regard to live birth rates per retrieval in poorer prognosis patients. The adoption of routine blastocyst culture for all patients would result in higher rates of single embryo transfers (SET), reduced incidence of multiple pregnancies and simplified laboratory protocols, thereby reducing costs.Methods/designMulticenter, non-inferiority randomized controlled trial (RCT) comparing blastocyst to cleavage stage embryo transfer in poorer prognosis patients with ≤5 zygotes on day 1 after fertilization. The primary outcome is live birth per retrieval. Secondary outcomes include: time to pregnancy, clinical pregnancy, ongoing pregnancy, miscarriage and multiple pregnancy rate (per retrieval). This trial will enroll 658 women with ≤5 zygotes on day 1 at 6 IVF centers over the course of 22 months.DiscussionIf the hypothesis is proven true, the data from this trial may facilitate the adoption of uniform blastocyst culture in all IVF patients.Trial registrationClinicalTrials.gov Identifier: NCT03764865. Registered 5 December 2019, Protocol issue date: 4 December 2018, Original.
Highlights
With improvements in in vitro culture techniques there has been a steady shift in practice to transfer embryos at the blastocyst stage (post fertilization day (p.f.d.) 5–7), when embryos reach the endometrial cavity during natural conception
The PRECiSE trial aims to determine whether transfer of cleavage stage embryos in patients with ≤5 available embryos results in similar pregnancy outcomes compared to the culture of all embryos to p.f.d. 5 in vitro followed by blastocyst transfer
We will evaluate potential negative consequences of cleavage stage embryo transfer and blastocyst transfer. The need for this randomized controlled trial (RCT) is clear, because previous trials have not assessed pregnancy outcomes in poorer prognosis patients and cleavage stage embryo transfer is routinely performed in this subgroup at many in vitro fertilization (IVF) centers
Summary
With improvements in in vitro culture techniques there has been a steady shift in practice to transfer embryos at the blastocyst stage (post fertilization day (p.f.d.) 5–7), when embryos reach the endometrial cavity during natural conception. A recent Cochrane meta-analysis of 27 randomized controlled trials (RCTs) by Glujovsky et al found a higher live birth rate, per transfer, in the fresh blastocyst transfer group compared to cleavage-stage transfer (odds ratio (OR) 1.48, 95% confidence interval (CI) 1.20 to 1.82) and no evidence for a difference in the rates of miscarriage, multiple pregnancies, and high-order multiples [1]. This analysis only included 539 patients and was not powered to identify subgroups of patients who may benefit from a cleavage-stage transfer. This approach is offered to patients with ≤5 zygotes on day 1 after fertilization and as a result 35% of all patients receive a p.f.d 3 embryo transfer, which is consistent with national trends
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