Endometrial Receptivity Analysis (ERA)

The ERA Endometrial Receptivity Analysis is a state-of-the-art diagnostic method that has been developed and patented in 2009 by IGENOMIX after over 10 years of research. This technique helps evaluate the woman’s endometrial receptivity from a molecular perspective.


ERA indicates the window of implantation (WOI), increasing your chances of successful embryo transfer.

An endometrium is receptive when it is ready for the embryo implantation. This occurs around days 19-21 in each menstrual cycle of a fertile woman.. This period of receptivity is what we call the window of implantation.


The lack of synchronisation between the embryo ready to be implanted and endometrial receptivity is one of the causes of recurring implantation failure. This is why it is imperative to assess the endometrium in order to determine the optimal day for embryo transfer. The ERA test requires an endometrial biopsy that should be carried out on day LH+7 (natural cycle) or day P+5 (HRT cycle). This biopsy is quickly and easily taken by a gynaecologist in their consultation room. After being sent away, the sequencing expression of 236 genes involved in the endometrial receptivity is analysed. An in-house designed computational predictor analyses the data obtained, classifying the endometrium as Receptive or Non-Receptive.


The ERA Endometrial Receptivity Analysis is a personalized genetic test to diagnose the state of endometrial receptivity in the window of implantation.


This molecular diagnostic tool is used to analyze the expression levels of 236 genes linked to the status of endometrial receptivity, using RNA sequencing taken from the endometrial tissue. Following the analysis, a specific computational predictor classifies the samples according to their expression profile as Receptive or Non-Receptive.

What is the Endometrial Receptivity Analysis used for?

The ERA Endometrial receptivity analysis is used to assess endometrial status and to determine whether or not the patient’s endometrium had a receptive gene profile at the time of biopsy.


The analysis reveals the personalised window of implantation of each woman. This data will enable a personalised embryo transfer (pET), synchronising endometrial receptivity with a blastocyst prepared for implantation.


The results from the analysis will determine if the woman was receptive or not at the time of sampling. If she is receptive, this implies that her window of implantation falls on the day of the cycle during which the biopsy was performed and the embryo could therefore be transferred to the uterus during this period.


A non-receptive status may imply a displaced window of implantation. The procedure will be performed once again according to the computational predictor, which will provide an estimate of the woman’s personalised window of implantation. This will facilitate the successful implantation of the embryo in a subsequent cycle with what is known as personalised Embryo Transfer (pET).

Who is the ERA Endometrial Receptivity Analysis for?

ERA helps reveal the patient’s personalized window of implantation before starting assisted reproduction treatment


This test has been performed on patients who have had recurring implantation failure with embryos of good morphological quality. This test is recommended for patients with seemingly normal uterus and normal endometrial thickness (≥6 mm), in which no problems are detected.


The ERA test can also be performed in patients with an atrophic endometrium, whose thickness never reaches 6 mm consistently. However, if a patient with normal endometrial thickness presents a punctual cycle with growth below 6mm we recommend canceling the cycle and starting a new one.


A displaced window of implantation is detected in approximately 25% of these patients. This analysis helps determine the personalised window of implantation, enabling personalized embryo transfer (pET) to be performed on the basis of these results.

What are the advantages of the ERA Endometrial Receptivity Analysis?

As an endometrial receptivity diagnostic method, the ERA determines the personalized window of implantation of each patient before she begins an assisted reproductive treatment.


The ERA test has proven highly sensitive and accurate in detecting gene expression profiles associated with receptivity.


Other endometrial status dating methods are based on histological criteria. However, these methods show a high degree of subjectivity and do not differentiate between slight yet significant molecular changes in the acquisition of the receptive phenotype.

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