Endometrial Receptivity Analysis (ERA)

* Endometrial receptivity is the state at which the endometrium is ready for embryo implantation to take place. This occurs around days 19-21 in each menstrual cycle of a fertile woman. Until now, the only study done on the endometrium was an ultrasound scan, and there was no analysis method available to help doctors in their clinical practice.

* The ERA test (Endometrial Receptivity Analysis) leads to the evaluation, at the molecular level, of the endometrial factor. This molecular tool allows us to diagnose whether the endometrium is receptive or not by analyzing the expression of a group of genes (238 genes) related to endometrial receptivity.

What is ERA for?

* The analysis reveals the timing of the implantation window and leads to a personalized embryo transfer (pET) timing based on the individual results obtained.

* A non-receptive result could imply a displaced window of implantation. Therefore, a second biopsy would be needed to validate this displacement. For that, a specific day for the second biopsy will be suggested according to the first result obtained. This will allow the implantation in a subsequent cycle with a personalized embryo transfer.

Which is the strategy to follow according to the ERA result obtained?

An endometrial biopsy is taken in an HRT cycle or in a natural cycle to perform the ERA test.

Result:‘Receptive’ If the patient has frozen eggs or embryos, or has fresh OvoDon eggs or embryos, these can be transferred within the same type of cycle (HRT or natural) in which a receptive result has been obtained. If a blastocyst is going to be transferred, it would be performed in a subsequent cycle in the same day in which the biopsy was performed, but if a day-3 embryo is going to be transferred, then it should be done two days earlier than the day of the biopsy.

If the patient does NOT have frozen eggs or embryos and wants to use their own eggs, a cycle of ovarian stimulation for egg or embryo cryopreservation will be performed. Embryo transfer will be performed in a subsequent cycle of the same type (HRT or natural) in which a receptive ERA test result was obtained.

Result: ‘Non receptive’ (with a recommendation of a new window of implantation) If the result of the first ERA test is non-receptive and the expression profile analysis suggests that the window of implantation may be displaced, it is necessary to validate this displacement with a second ERA test. This second analysis will identify the day when the endometrium shows a receptive status, and therefore the thawing of eggs or embryos and their transfer must be scheduled to coincide with the day for which the receptive result has been obtained.

Result: ‘Non receptive’ (without a recommendation for a new implantation window) If the result of the first ERA test is non-receptive and the expression profile analysis does not suggest a displaced window of implantation, unfortunately we are unable to offer a therapeutic solution. This happens in less of 1% of patients.