Repeated failure of pregnancy? Know all about the ERA test

Multiple failure of pregnancy can be mentally and physically exhausting. Endometrial Receptivity Array (ERA) is an advanced test that assists in determining the best time for embryo transfer and achieving high pregnancy rates. The ERA test is an innovative approach to addressing implantation issues.

Even with healthy embryos and a normal uterine cavity, many couples attempting to conceive using Assisted Reproductive Technology such as IVF fail the embryo implantation process. This occurs due to underlying endometrial health problems (the inner lining of the uterus) or the uterus’s inability to retain a healthy embryo. While undergoing IVF treatment, those couples that are unable to conceive even after 3 cycles of failed embryo transfers with good-quality embryos are said to be suffering from recurrent implantation failure.

The ERA test determines how receptive your endometrium is, by assessing its readiness for implantation at the genetic level.

Significance of ERA Test

Until recently, experts believed that embryo quality was the sole determinant of a successful IVF cycle. However, recent research has discovered that while the quality of the embryos is important, the uterus’ receptivity also plays a significant role in determining the fate of the IVF cycle. Science and medicine now allow us to determine the receptivity of a woman’s uterus in relation to the embryo. The ERA test not only measures uterine receptivity but also assists in determining the exact time for embryo transfer called, the “window of receptivity”.

The ERA test is unique as it examines endometrial receptivity as a byproduct of endometrial lining gene expression at specific times during a woman’s ovulation cycle. It tracks 238 different genes and determines an implantation window that is unique to each patient. In detecting gene expression profiles associated with receptivity, ERA has highlighted high sensitivity and specificity. Therefore, this test provides significant advantages because it reduces the number of IVF cycles a couple must go through to achieve a successful pregnancy, along with lowering miscarriage risk.

What is the window of receptivity?

The window of receptivity is the period of time when your uterus is ready to receive an embryo at the adequate stage of development for implantation and, thus, pregnancy.

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The endometrium, the lining inside the uterus, plays a significant role in the uterus. In addition to a certain thickness, the endometrium must express the correct genes that signal to a potential embryo that it is ready for implantation, a process largely influenced by the hormone progesterone.

The embryo, on the other hand, must be mature enough to successfully implant (it must have reached the blastocyst stage, which is day 5 or 6 of growth).
Furthermore, the embryo must be chromosomally right in order to implant and result in a continuing pregnancy (abnormal embryos will usually fail to implant or result in a miscarriage).

If both the embryo and the uterus are ready at the same time, implantation and pregnancy can occur. However, if the window is missed and the embryo is not at the correct developmental stage by the time it reaches the uterus, it lacks the correct number of chromosomes, or the endometrium is not expressing the correct genes, implantation and pregnancy will not occur.

This ‘window of receptivity’ exists in both natural and IVF conception.

How is the ERA test performed?

A biopsy of the uterine inner lining (endometrium) is taken and sent for analysis. Typically, the biopsy is performed at the same time that doctors would transfer an embryo into a patient’s uterus.

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The ‘prep’ cycle involves similar steps as a ‘real’ transfer cycle, including ingesting oral and self-injected medications to stimulate your uterine lining. Transvaginal ultrasounds and bloodwork visits are advised during this prep cycle to monitor response to the medications. The doctor performs the biopsy at the end of the prep cycle. The biopsy involves injecting a flexible plastic tube into the woman’s uterus (using a vaginal speculum) and moving it back and forth to collect tissue from the uterine lining.

This procedure doesn’t require anesthesia as it is not painful, but it may induce some discomfort that can be relieved with simple analgesics.

A normal ERA report is termed receptive endometrium, suggesting other possible causes for IVF failures.

Also read: Multiple pregnancies: Complications that may occur when you give birth to twins or triplets

An abnormal ERA report represents either pre-receptive or post-receptive endometrium. Patients whose reports are abnormal indicate that their endometrium is not ready to receive and implant embryos and undertake conventional progesterone therapy as their next steps.

Earlier, doctors were compelled to repeat IVF cycles indefinitely until pregnancy was achieved. ERA, now, offers the opportunity for timely implantation. This improves the success rates of pregnancies and minimizes the time required to achieve it.