Timeline graphic that outlines the process of the endometrial receptivity assay ERA.

Should you consider the ERA test prior to your embryo transfer?

The egg retrieval is done, the embryos have been created and are frozen.  A patient may now ask, “Should we postpone an embryo transfer to do an ERA?”  To best answer that question one must understand the processes related to this test and weigh the benefits. 

The Endometrial Receptivity Assay (ERA) test involves three weeks of estrogen and progesterone medications followed by an office sampling of the uterine lining tissue during a procedure known as an endometrial biopsy.  The tissue obtained is sent for specialized testing to identify an optimal number of days of progesterone treatment prior to a frozen embryo transfer.  The ERA is often not covered by insurance, the biopsy is uncomfortable, and results take several weeks to return.   Reassuringly, according to Riestenberg and colleagues in Fertility and Sterility, for the first embryo transfer, most patients can omit the ERA; particularly, those with three or more PGT-A euploid embryos available. For most individuals, the typical timing of an embryo transfer will suffice. However, for patients with multiple failed embryo transfers or for those patients with very few embryos available, there may be benefit to considering the ERA.

Mira Aubuchon, MD