I have been a big proponent of single-embryo transfer for many years. Despite this, less than 10% of patients at InVia Fertility Specialists will choose to have an elective single-embryo transfer (eSET)! When questioned about his, a lot of my patients state that they would prefer to have twins even when they have been explained the potential risks of a twin pregnancy and costs of raising twins.
Recently the Practice Committee of the Society for Assisted Reproductive Technology and Practice Committee of the American Society for Reproductive Medicine published an its opinion regarding the elective transfer of a single embryo (eSET) during in vitro fertilization (IVF).
eSET after IVF has been advocated as the only effective means to avoid multiple pregnancy in IVF cycles. This applies to patients who have more than one “top” quality embryo available for transfer but choose to transfer only one embryo. Historically, to compensate for low rates of implantation for individual embryos and achieve “acceptable” pregnancy rates, multiple embryos have been transferred to the majority of IVF patients. Consequently, IVF carries a high risk of multiple pregnancy and its associated adverse effects on mothers and children, as detailed in a previous blog. However, as implantation rates (IRs) have improved, the practice of transfering multiple embryos is being reassessed.
Utilization of eSET has increased over the past decade. Use of eSET in the United States has lagged behind that of many other countries. In the United States during this time, the use of double embryo transfer (DET) has increased and twin pregnancy rates have remained essentially unchanged.
Elective Single Embryo Transfer vs. Double Embryo Transfer
There have been several randomized controlled trials (RCT) comparing cleavage-stage eSET and subsequent cryo-preserved embryo transfers with DET and have demonstrated similar pregnancy rates and live birth rates PRs with a substantial reduction in multiple gestations.
An RCT comparing eSET and DET of blastocyst-stage embryos demonstrated no statistical difference in pregnancy rates and a reduction in multiple gestation rate from 47% to 0%.
There is evidence from well controlled nonrandomized trials and clinical reports that if the contribution of cryopreserved embryo transfers is included, cumulative success rates per retrieval are similar for eSET and DET.
Published studies of the cost-effectiveness of eSET versus DET have included only costs to achieve a pregnancy or through 4–6 weeks postpartum.
Who Is a Good Candidate for Elective Single Embryo Transfer?
eSET is most appropriate for those with a good prognosis:
age <35 years,
more than one top-quality embryo available for transfer,
first or second treatment cycle,
previous successful IVF, and
recipients of embryos from donated eggs.
Women aged 35–40 years may be considered for eSET if they have top-quality blastocyst-stage embryos available for transfer.
Decisions regarding eSET of cryopreserved embryos should take into consideration prognosis, embryo quality, and success rates of the individual cryopreservation program.
Challenges to Increased Use of Elective Single Embryo Transfer
One particular difficulty in promoting fresh eSET with FET one at a time in subsequent cycles is the way that IVF clinic data are reported in the United States. Pregnancy rates are reported per cycle initiated or per transfer and do not capture cumulative success rates of subsequent transfer of frozen embryos derived from the same cycle. Therefore, clinics promoting eSET may be at a disadvantage because they appear to have lower “success” rates than those utilizing DET, even though the total “success” rates are similar. Physicians and patients will require additional education to understand that the data now reported do not necessarily accurately reflect the likelihood of pregnancy. Changes in methods of IVF clinic data reporting may clarify this.
Other challenges include:
provider and patient education, this includes the use of pamphlets, DVD’s and other material explaining the risks of multiple births.
financial considerations, it is well-established that in states with no insurance coverage for IVF, there is a tendency to transfer more embryos. As more states have laws that mandate infertility treatment coverage the incidence of eSET may increase.
embryo selection, this may include the use of pre-implantation genetic screening to select the “normal” embryos, which have a higher chance of implantation and
successful cryopreservation. It is imperative to have an optimal cryo-preservation program for eSET to work.
Selection and successful cryopreservation of the embryos with the highest IR will facilitate wider use of eSET.
Elective SET should be offered to patients with a good prognosis and to recipients of embryos from donated eggs.
IVF centers should promote eSET when appropriate through provider and patient education.
Improvements in embryo selection should further increase the application of eSET.
Dr. Karande is Board Certified in the specialty of Obstetrics and Gynecology as well as the subspecialty of Reproductive Endocrinology and Infertility. He is a Fellow of the American College of Obstetricians and Gynecologists and Member of the American Society for Reproductive Medicine.