The ERA Test in IVF programs – how, when and why?

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Endometrial Receptivity Analysis. When is it appropriate? Why is it used and is it helpful?

Watch 3on1 #IVFANSWERS to get THREE answers from three great experts to ONE question which this time is: The ERA Test in IVF programs – how, when and why? From our experts, you will know how the procedure is done. When it should be used and who can be advised to use it. And if it really works.

  • Dr Oksana Babula – Reproductologist Clinic EGV
  • Dr Juan José Sánchez Rosas – Gynaecologist specialising in Reproductive Medicine URE Gutenberg Centre Reproduction Unit
  • Dr Alexandra Izquierdov- Medical Director at ProcreaTec

Dr Oksana Babula, Clinic EGV, Latvia

Answer from Dr Babula

The ERA (Endometrial Receptivity Array) is a very simple test. It’s normally performed on women who had multiple unsuccessful embryo transfers. The goal of the test is to figure out the perfect moment for the implantation to take place. It’s mostly performed during stimulated cycles – on a certain day of progesterone treatment, we do an endometrial biopsy. The sample we acquire is then sent off for genetic testing. The results of this test tell us the perfect window of implantation. This timing window applies to all types of embryo transfer, however, the test is most commonly performed during donor egg or donor embryo treatments.

Current research based on the results of ERA tests state that around 25% of all donor egg or donor embryo patients have problems with implantation. The reasons for that can be numerous – from embryo quality to immunological causes. However, if the embryo is of good quality and the transfer does not result in a pregnancy, it’s worth considering an ERA test.


Dr Alexandra Izquierdo, ProcreaTec, Spain

Answer from Dr Izquierdo

Successful embryo implantation depends on two main factors: embryo viability and a proper endometrial environment. The short period of time in which the uterus is receptive to embryos is called the window of implantation. It is determined by the balance between two hormones – oestrogen and progesterone. For most women, this period of receptivity occurs around six days after ovulation and lasts for four days afterwards. However, for some patients, this implantation window can be somehow displaced – as in, take place a little bit earlier or later.
When treating infertile women, timing is key. If the embryo is implanted outside of this window of implantation, it could find itself in an environment not ready for it – whether it’s pre-receptive or post-receptive, transferring embryos at the wrong time can result in implantation failure.
The endometrial receptivity test (ERA) allows us to accurately determine the implantation window of each patient. It’s a genetic test that evaluates several specific genes in endometrial tissue using RNA sequencing. In order to perform the test, an endometrial biopsy must be performed on a specific day of the luteal phase.
The analysis classifies the endometrium as receptive or non-receptive. Thanks to the information provided by the test, we can personalize the transfer time for each patient.
Obviously, the technique seems like a sure-fire way to improve implantation chances; current research, however, doesn’t support its widespread use, as it doesn’t help every patient equally. Currently, we consider it to be most useful for patients experiencing recurrent implantation failure when using high-quality embryos. Within these specific circumstances, the risk of having a displaced implantation window is significantly increased (up to 25% according to current data).
Moreover, new genetic tests for the endometrium are becoming available, which offer additional information about the uterine environment – such as microbiological conditions or immunological status. These tests may soon enter widespread use for other patients as well.


Dr Juan José Sánchez Rosas , URE Gutenberg Centre Reproduction UnitSpain

Answer from Dr Sánchez Rosas

Embryo implantation is a very complex process that takes place at a very specific moment in the endometrial cycle. Not every woman has the same receptivity window, which is an important factor for the success of IVF programs. When we experience IVF failures, we have to know what the possible cause was. While the embryo is usually the main cause of failure, as its quality determines the chances of pregnancy, we can’t forget that the endometrium is a very important part of the cycle. We have to know that it’s ready at a very specific moment. If we encounter an IVF failure despite using high quality embryos, or if we experience miscarriages or biochemical pregnancies, we need to investigate further.
The endometrial receptivity test tells us whether there’s a problem with the endometrial receptivity window, which would mean the transfer needs to be performed at a slightly different time. Some patients are receptive slightly earlier or later than we initially think they are; once we determine that’s the case, we adapt our protocols.
In order to perform an endometrial receptivity cycle we prepare a normal cycle; instead of transferring the embryo, however, we perform an endometrial biopsy at the moment we would normally perform the transfer. Through genetic analysis of the sample lets us determine the exact time we need to perform the transfer at.

You may also be interested in reading: Will the baby look like me? Donor egg IVF concerns.


3on1 IVFanswers - three answers to one question

Three IVF experts answering the same question.

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