Endometrial Biopsy: What to Expect

Endometrial Biopsy

Let’s start with the basics. The endometrium is the soft fleshy lining tissue in the very central portion of the uterus. When it is well developed, by week 3 of your cycle, it makes secretions that can provide nutritional support to an embryo, and it makes certain adhesive molecules to facilitate implantation. However, it takes two to tango. The embryo must be good quality in order to implant as well. If you are not pregnant, the top two-thirds of this endometrial tissue sheds as the period each month.

An endometrial biopsy is a small sampling of this tissue done midcycle or later to permit microscopic detailed assessments. The tissue can be sent to a microbiology lab to incubate and test for the presence of any bacteria. A normal endometrium does not grow bacteria. If there are bacteria, detected, then treatment with antibiotics is indicated. The tissue can also be sent to pathology to check for inflammatory cells. This type of test is called a CD-138 staining. The tissue is fixed to a microscope slide and processed with special stains to highlight inflammatory cells. Should such inflammatory cells be present, then antibiotic treatment would also be indicated. And lastly, the endometrial tissue could be sent to a special lab to see if the molecular gene expression is appropriate for the time of implantation.  This is an endometrial receptivity assay and is potentially helpful for women who have failed implantation with chromosomally normal embryos.

Whenever we test the uterus, there is cramping, so the first step is to pre-medicate the patient to minimize cramping. Dr. Moomjy will review with you the pre-medication options and make sure that you are comfortable for this test.  Although the crampy part is typically less than 5 minutes, we schedule time with the patient for 45 minutes: in order to have time for an ultrasound; for a local anesthetic; for the passage of the sterile plastic catheter to aspirate a few strips of tissue; for discussion; and for a few minutes of rest afterwards. When you leave the office, you may go about all of your activities that day normally. It is usually one week for us to receive reports from the lab(s) to determine if we are completely reassured by normal findings, or if we have to pursue treatment based on lab findings.

Maureen O'Brien Moomjy, MD, FACOG

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