Understanding ERA Endometrial Biopsy

Physicians use ultrasound technology to examine the thickness and pattern of the endometrial lining in preparation for embryo implantation during an IVF cycle. Although ultrasound is an established entity, there is a subset of patients who have an appropriate endometrial lining and transfer of morphologically high-quality embryos, who fail to successfully conceive and have a live birth following an IVF cycle.

It is thought that some patients may have alterations of their “window of implantation” that may decrease their implantation rate and pregnancy success using traditional ultrasound and hormone assessment. The endometrial receptivity assay (ERA) attempts to analyze the endometrial lining at the molecular level, and elicits further information about this window of implantation by evaluating 248 genes.

How can an ERA biopsy help with embryo implantation?

In order to understand ERA testing, it can be helpful to review how the female reproductive system works. Conception is a complex biological process with a significant number of variables.

First, the woman’s ovaries need to release an egg. This process is known as ovulation. Once released the egg is only viable for 12-24 hours. The egg must be fertilized by the man’s sperm that travels to the fallopian tubes where it meets the egg for fertilization.

Second, the resulting embryo, which will be in the blastocyst stage of development, implants into the uterine lining, where it will then develop. In order for implantation to occur, the uterine lining must be capable of receiving and nurturing an embryo. During each monthly cycle, a woman’s uterine lining is most receptive for a period of 4-5 days known as the “window of implantation.”

ERA biopsies can be used to identify when a woman’s uterine lining is in that window of implantation. ERA is also a diagnostic tool used to determine if a woman’s uterine lining is a contributing factor in recurrent IVF implantation failure and recurrent pregnancy loss.

Who should consider an ERA biopsy?

ERA biopsy may be an option for women already undergoing infertility treatment and is typically recommended for women who have had previous IVF cycle failures or have experienced miscarriage or recurrent pregnancy loss.

The ERA endometrial biopsy is not part of a female fertility evaluation and is not typically recommended for first-time IVF patients. However, it’s always important for women to discuss their personal situation with their doctor.

What happens during an ERA biopsy?

The endometrial receptivity array procedure will typically begin 1-1 ½ months prior to a frozen embryo transfer. The woman will begin taking sequential hormones, including estrogen and progesterone in advance of the procedure, as she would in preparation for a frozen embryo transfer. An endometrial biopsy is performed on the standard embryo transfer day (in lieu of an actual embryo transfer), when the window of implantation is expected to occur.

The biopsy is a straightforward, outpatient procedure with minimal discomfort. During the biopsy a small instrument called a pipelle is inserted through the vagina. The doctor will use the pipelle to “scratch” the uterine lining and obtain a small amount of tissue for testing. Some women experience cramping or light bleeding during or after the procedure.

The sample will be sent to a lab where molecular analysis is completed to determine the best time to attempt embryo implantation in a future IVF cycle. There are three potential results.

Pre-receptive. The lining is not yet ready to receive an embryo, and implantation is less likely to occur.

Receptive. The lining is ready to receive the embryo, which is most likely to implant.

Post-receptive. The lining has already reached the stage for optimal embryo implantation but is no longer in that stage. The embryo is less likely to implant at this time.

If the sample results come back as pre-receptive or post-receptive, doctors will then adjust the scheduled embryo transfer to account for these changes

It is important to note that there is little research to suggest that scratching or disturbing the uterine lining in this manner will decrease the ability of an embryo to implant. It also does not make implantation more likely. There is certainly more room for research on this matter, and our physicians will follow all new information about ERA endometrial biopsy to determine which patients may benefit from this technology.