Revisiting Elective Single Embryo Transfer (eSET)

The transfer of a solitary embryo gains more support in North America. The idea is not new and was the focus of early IVF. Most often it has been applied to those patients with medical contraindications for multiple pregnancies. Ten years later, eSET (elective single embryo transfer) gains validity as a practice modicum in assisted reproductice technologies although it is steeped with controversy and emotion. It was intended to be a reasonable answer to high proportion of multiple pregnancies – embraced by some and antagonized by others.

The steadily increasing incidence of multiple gestation has called us to develop strategies for controlling the rate of higher order multiple gestation. In part what drives the pendulum swing toward eSET is a significant improvements in the technology afforded (IVF stimulation protocols, competent and competitive laboratories).

Continued increases in live birth rates from eSET occur when the ideal candidates and their embryos for eSET are identified. Prognostic criteria to determine these patients have been developed and now the data is collected and honed. Selection criteria is most often based upon female (preferably under 36 years), number of quality embryos available for transfer, treatment history and ability for laboratory effectively to maintain extended embryo culture. In addition, subsequent effective cryopreservation-techniques afforded quality blastocysts to be utilized in the future.

From scientific studies performed both here and abroad, two of the strongest associations between eSET and live birth rate are the woman’s age and the quality of the advancing embryos. Of course, these data should not be surprising. They serve as a guide for fine-tuning how aggressive one should be with the number of embryos for transfer. Interestingly, the cause of the infertility may not be of issue. The only caveat is significant uterine factor.

Again, this finding is not surprising. The analogy is to the growth of a flower. Both the seed and the soil must be prime for cultivation just as the embryo and endometrium must be synchronized. This information calls us as physicians to optimize each couple’s fertility potential, and to afford a diagnosis when possible. Careful examination and priming of the uterus is coupled to attentive cultivation of the embryo. The goal is to enrich the world, one baby at a time.

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