Endometrial Receptivity Array

Implantation failure is one of the final frontiers in IVF treatment and research, and is estimated to account for around 2/3rd of cycle failures.

Recent theories in the field of reproductive medicine are moving away from citing the embryo as the sole determinant of an in vitro fertilization (IVF) cycle’s success. While it is true that embryo quality is the strongest predictor of implantation, current research shows that uterine receptivity may also play a fairly significant role in the success of a cycle. In fact, some of the latest reproductive findings encourage patients to freeze their embryos and transfer them in a later cycle once the uterine lining has recovered from the effects of harsh fertility drugs.

A new test, the Endometrial Receptivity Array (ERA), operates on a similar premise and provides insight into how receptive a woman’s uterus will be at a particular stage in her menstrual cycle. Essentially, this helps fertility doctors determine the best time to transfer an embryo in hopes that it will implant.

The quality of embryos is the best predictor of success, but for couples who do not conceive despite multiple transfers of embryos using genetic testing like preimplantation genetic diagnosis (PGD) or preimplantation genetic screening (PGS) or egg donation, there could be endometrial factors involved, even when the lining of the uterus appears to be normal and prepared by ultrasound parameters. The ERA test is the first of its kind to examine endometrial receptivity as a product of gene expression of the endometrial lining at specific times during a woman’s cycle. The test looks at the cyclical pattern of 238 different genes. These genes are implicated in the formation of a normal endometrium which is adequately prepared to support implantation of a blastocyst. We now know that certain genes are ‘switched on’ when the endometrium is receptive, and can pinpoint these genes and check whether they are switched on or not. This gives a good idea of whether the endometrium is ‘pre-receptive’, ‘receptive’ or ‘post-receptive’. The test is carried out in the month prior to the treatment cycle, and the results will determine the exact timing of the embryo transfer in the month of treatment. There are many scientific research papers to support the investigation of these factors. The results of the testing not only tell us that the lining isn’t good enough, but tells the physician how to fix it; we either add or subtract days of progesterone support, to make the lining properly prepared.

Recent data is extremely encouraging-demonstrating a vast improvement in pregnancy rates in those patients who then adjusted their medication as indicated by the assay. This test is relatively easy; an endometrial biopsy can be performed in just a few minutes in your doctor’s office. The adjustment in protocol changes only the number of days of progesterone support before transfer; no additional medication is needed. This risk-free test and adjustment in stimulation protocol seems to be extremely effective in improving ongoing clinical pregnancy rates in many women who have suffered from repeated failures with high-quality embryos.

What is now concluded is that some of the patients with “Implantation failure” should not be categorized as having a pathological condition or disease but as patients in whom embryo transfer timing should be personalized because their endometrial timing is different.

In other words; the concept of “Implantation failure” is revisited as “timing failure to implant”, in an otherwise normal endometrium.

Personalized Embryo transfer guided by endometrial receptivity array is able to obtain successful results in women who have faced repeated implantation failure despite good embryo quality.

When and how will the ERA be carried out?

It will be carried out in a cycle prior to your treatment cycle. You will be put on hormonal replacement (Estrogen Tablets) to prepare your endometrium and progesterone will be added approximately 14 days later when your treating doctor is satisfied with how your endometrium looks. This is exactly what will be done in your treatment cycle as well. A small biopsy will be taken from your endometrium on the 6th day of starting progesterone.

This procedure will be carried out in your doctor’s office and does not require anaesthesia.

The sample will be sent to the lab and you will be advised when to stop your medications following which you will get your periods.

Once the results of your tests are in you will receive a call from your doctor/clinic to discuss the further course of action.

How will the results of ERA be interpreted?

Either of the following results will be obtained from the laboratory:

  • RECEPTIVE: that means that the embryo transfer should be exactly on the day the biopsy was taken and the cycle should be mimicked in the treatment cycle.

  • The lab may advise the doctor to do a transfer one day prior or one day later depending on where they think the endometrium was in the cycle when the biopsy was taken.

  • The result may come as inconclusive and your doctor may need to take another biopsy.