Endometriosis vs. Endometrial Biopsy: What Testing Shows

Medically reviewed by Monique Rainford, MD

Endometriosis is a condition in which tissue that is similar to the tissue that lines the uterus grows in areas outside of the uterus, typically in the abdomen and pelvis. Endometriosis is confirmed through a biopsy collected using a surgical procedure called a laparoscopy.

An endometriosis biopsy is different from an endometrial biopsy. While an endometriosis biopsy is a surgical procedure to detect the presence of endometriosis tissue, an endometrial biopsy is a less-invasive procedure that examines endometrial tissue from inside the uterus to look for abnormalities in the endometrium.

This article will look at what endometrial biopsies and endometriosis biopsies are, what they test for, how they are performed, and what happens after them.

Does Biopsy Diagnose Endometriosis?

The only way to confirm a diagnosis of endometriosis is through surgery, usually a surgery called a laparoscopy. In it, a small incision is made in the abdomen, and a tube with a camera and a light is inserted to examine inside the abdomen and pelvis.

During this procedure, a small sample of abnormal tissue can be removed to be analyzed (called a biopsy). It is usually performed under general anesthesia.

What Is an Endometrial Biopsy?

An endometrial biopsy is a procedure typically done in a healthcare provider's office or as an outpatient procedure. It usually doesn't require general anesthesia, Rather, local anesthesia is used to numb the area.

During an endometrial biopsy, a very thin, flexible tube is inserted into the uterus through the cervix. A small amount of endometrium is removed using suction.

The tissue sample is then examined under a microscope to check for things like abnormal cells.

Endometriosis vs. Endometrium

While they sound similar, endometriosis and endometrium are two different things.

Endometrium

The endometrium is the lining (mucous membranes) that covers the inner walls of the uterus. Each menstrual cycle, the endometrium thickens in preparation for the potential implantation of a fertilized egg. If implantation occurs, this lining provides the fertilized egg with everything it needs to grow and support a pregnancy.

If implantation does not occur, most of the thickened membrane tissue is shed through menstruation. The hormones estrogen and progesterone regulate the process of thickening and then shedding of the endometrium.

If no pregnancy occurs, a new thickened endometrium is grown with each menstrual cycle.

Endometriosis

With endometriosis, tissue that is similar to the endometrium grows in areas outside of the uterus, in locations such as:

• The fallopian tubes

• The ovaries

• The pouch of Douglas (area between the uterus and rectum)

• The bladder or bowel (less common)

Endometriosis tissue also responds to the hormonal signals of the menstrual cycle, causing it to thicken and break down. Unlike the endometrium, endometriosis tissue has nowhere to exit the body, so it can continue to build up. This can cause issues such as:

• Inflammation and swelling in the affected and surrounding areas

• Scar tissue

• Chronic pain

• Adhesions (when fibrous tissue causes organs to stick together)

• Heavy periods

• Problems with fertility

Reasons to Have an Endometrial Biopsy Test

An endometrial biopsy may be performed if there is:

• Bleeding after menopause (when menstrual cycles have not occurred for 12 straight months)

• Abnormal or irregular menstrual bleeding

• An absence of menstrual bleeding

• Heavy bleeding

• Extended menstrual bleeding

• Vaginal bleeding without an explanation

• Suspected endometrial abnormalities

• Thickened uterine lining seen on an ultrasound after menopause

• Abnormal bleeding from hormone therapy medications, changes in hormone levels, or taking the breast cancer medication tamoxifen

• Endometrial cancer (or suspected)

• A need to assess the response to treatment for endometrial hyperplasia

Endometrial Biopsy vs. Colposcopy

A colposcopy looks for abnormal cervical tissue. In a colposcopy, you will lie down on an exam table. A speculum is then inserted into the vagina to separate the walls and allow the cervix to be seen.

The cervix is washed with a vinegar-like solution that makes abnormal cells easier to see.

Using a colposcope (an instrument that resembles binoculars on a stand with a bright light), the healthcare provider will take a close look at the cervix. The colposcope does not touch you or go inside the vagina.

The healthcare provider may do a biopsy. They may take tissue from the outside of the cervix to biopsy, from the inside of the cervix to biopsy, or both.

Endometriosis Biopsy During Laparoscopy and Laparotomy

If endometriosis is suspected, a laparoscopy and biopsy may be performed to look for endometriosis and make a diagnosis. It is usually an outpatient procedure performed under general anesthesia.

During a laparoscopy:

• Small incisions, usually under 1 inch in length, are made in the abdomen.

• The abdomen is filled with carbon dioxide to push the abdominal wall away from internal organs.

• Using tools such as a laparoscope (a thin tube containing a light and a camera), and a small probe (used to move the pelvic organs), the surgeon looks for abnormalities such as endometriosis lesions (areas of endometriosis tissue).

• The surgeon may also inject fluid through the cervix, uterus, and fallopian tubes to see if they are open.

• If no abnormalities are noted, the surgeon closes the incisions using one or two stitches.

• If endometriosis tissue is found, the surgeon may remove a small sample to do a biopsy.

• Sometimes, the surgeon removes the endometriosis tissue during the same procedure.

If a larger opening is needed, a laparotomy will be performed.

Surgeons Must Excise Endometriosis to Biopsy It

While less-invasive methods can be used to look for signs of endometriosis, the only way to definitively diagnose endometriosis is through surgery.

Results From Biopsy: Endometriosis vs. Endometrial

Endometriosis biopsies and endometrial biopsies produce different types of results.

Abnormal results from an endometriosis biopsy primarily show the presence of endometriosis tissue.

An endometrial biopsy checks for several abnormalities and other factors and can present a wider variety of abnormal results, including:

• Abnormal tissues indicating conditions such as polyps

• Uterine infections, such as endometritis

• Endometrial cancer or abnormal cells that could lead to cancer

• The effect of hormonal treatments on the endometrium

• Endometrial hyperplasia (abnormal thickening of the endometrial lining that can be a risk factor for endometrial and uterine cancer)
  

• The type and grading scale of endometrial cancer
  

Treatment Plan After Biopsy: Endometriosis vs. Endometrial

Treatment options depend on the results of the biopsy.

Endometriosis

If endometriosis is diagnosed, treatment options can include:

• Medications, such as contraceptives (which decrease estrogen levels) or gonadotropin-releasing hormone (GnRH) analogues, which induce temporary menopause

• Surgical removal of lesions

• Removal of the uterus (hysterectomy) and/or ovaries (oophorectomy) in serious cases

Endometrial

Treatment after an abnormal endometrial biopsy is determined by the condition or abnormality that is found.

If a diagnosis of endometrial cancer is made, surgery is usually performed to remove the uterus, cervix, ovaries, fallopian tubes, and sometimes lymph nodes and other tissue (to be tested).

During surgery, the cancer will be staged to determine if further treatment is needed. In more advanced cases, additional treatment, such as chemotherapy and/or radiation therapy, may be needed.

Summary

The endometrium is the tissue that makes up the lining of the uterus. During the menstrual cycle, this tissue thickens in preparation for a possible pregnancy, then sheds during menstruation if pregnancy does not occur. The process is repeated each menstrual cycle.

Endometriosis is tissue that resembles and responds to hormones similarly to the endometrium but grows outside the uterus in areas such as the pelvic organs. Endometriosis tissue also thickens and breaks down during the menstrual cycle but builds up inside the body instead of being expelled.

An endometrial biopsy is typically done without the use of general anesthesia. A small amount of tissue is removed through the cervix and tested for abnormalities such as hormonal imbalances, endometrial hyperplasia, and endometrial cancer.

An endometriosis biopsy is performed under general anesthetic using surgery, typically a laparoscopy. A small tissue sample is removed through a small incision in the abdomen and tested primarily for endometriosis tissue.

Treatment for endometriosis can involve taking medications such as hormone therapy, removing endometriosis lesions with surgery, or removing the uterus and/or ovaries with surgery.

Endometrial cancer is usually treated with a total hysterectomy (removal of the uterus, cervix, ovaries, and fallopian tubes) and may be followed by chemotherapy and/or radiation therapy.