Endometriosis is a chronic condition that usually affects women in their 30s and 40s, but symptoms can develop at any time while a woman is menstruating. “Endometriosis occurs when endometrial tissue, the tissue of the inner lining of the uterus, starts to grow outside of the uterus,” says Veerle Bossuyt, MD. 

The tissue can cause irritation and sometimes severe pain during menstruation and intercourse. The condition can also lead to infertility. Only rarely does it spread beyond the pelvic region.

A patient must undergo a biopsy of a small tissue sample from the uterus. The biopsied tissue is analyzed under the microscope by a pathologist, who confirms the presence of endometriosis or not. 

“Sometimes the diagnosis of endometriosis cannot be confirmed after the first biopsy, and additional evaluation is necessary. Dr. Bossuyt says. “At Yale Medicine, all your physicians, including the pathologists, will work together to attempt to minimize complications, to confirm the diagnosis and to provide appropriate surveillance for rare but important complications.”

Endometriosis is best diagnosed by a subspecialty of gynecologic pathologists, who focus on gynecologic conditions and are familiar with the rare types of endometriosis that may occur. “That said, the diagnosis of endometriosis is a team effort that includes the physician treating the patient,” Dr. Bossuyt says. Having such specialized pathologists is something that sets Yale Medicine apart from other medical institutions.

If inflammation exists around the abnormal endometrial tissue, this could make it difficult for the doctor to remove a sample from the area for diagnosis. “These reactive changes may also obscure the microscopic structure of the tissues that allow the pathologist to make a diagnosis under the microscope," Dr. Bossuyt says.

“Reactive changes including inflammation, fibrosis and evidence of recent or previous bleeding are almost always present,” Dr. Bossuyt says. “And in many cases, these can be so dramatic that they raise the possibility of malignancy, or the presence of a tumor that is cancerous." This is why it is important to have experienced pathologists review the biopsy sample.

Endometriosis is associated with a very small increased risk of cancer. Because of the volume of gynecologic specimens the Yale Medicine pathology department handles, its physicians have abundant experience finding cancers caused by endometriosis.

Yes, for example, if the woman requires one or several surgeries. "Pathologists will carefully examine each specimen removed during surgery to confirm that the symptoms the woman is experiencing are due to endometriosis, and to confirm there is no malignancy," says Dr. Bossuyt.