The ERA (or endometrial receptivity array) is a genetic test that diagnoses the state of endometrial receptivity in the window of implantation in women. This molecular diagnostic tool is used to analyse the expression levels of 238 genes related to the status of endometrial receptivity.
Probes for these 238 genes are hybridized with RNA obtained from an endometrial tissue sample in a custom microarray. After hybridization the signal intensities are read by a computerized predictor and the sample is classified as „Receptive” or „Non-Receptive” according to its specific expression profiles.
ERA tests reveal the timing of the implantation window and permits personalised embryo transfer (pET) timing based on the individual results obtained.
Why choose the ERA Test?
The ERA test is recommended for younger women with at least 3 failed embryo transfers or for patients 37 years or more with 2 failed embryo transfers.
The ERA test has shown high sensitivity and specificity in detecting gene expression profiles associated with receptivity. Endometrial stage dating has been classically determined based on histological criteria. However, this method has shown not to discriminate between fertile and infertile patients and involves a high degree of subjectivity, meaning these results cannot be applied in the clinic. The ERA test overcomes these problems.
How are samples taken?
To perform this analysis it is necessary to take an endometrial biopsy from women in their natural cycle or hormone replacement therapy cycles, at a time corresponding to the phase of endometrial receptivity. That is, in the natural cycle at day 21, seven (7) days after the LH (luteinizing hormone) surge (LH+7, or 6 days after the follicle rupture, when this is monitored by ultrasound) or after five (5) full days of progesterone impregnation in Hormone replacement therapy (HRT) cycles.
After the biopsy is taken it is immediately introduced into an "ERA cryotube" which contains a fluid that facilitates the preservation of the tissue.