Supervised by Kaori Koga, M.D., Ph.D., Associate Professor, Department of Obstetrics and Gynecology

Endometriosis is a disease in which an endometrium-like tissue (endometriotic tissue) grows outside the uterus. Endometriosis is worsened every time you have a period because the tissue proliferates with menstruation. The endometrium is a tissue in the uterus and is excreted from the uterus when unnecessary (which is called menstruation). In contrast, an endometriotic tissue growing outside the uterus cannot leave from the body and induces inflammation in the body, causing pain and infertility. If endometriosis occurs in the ovary, a cyst full of blood may be formed, which is said to be a high risk of rupture or transforming to ovarian cancer. Endometriosis can occur even in a site that is far away from the uterus, such as the groin or umbilical region. Endometriosis in the diaphragm or the lung may cause pneumothorax or hemosputum.

In the woman’s body, ovulation usually occurs once a month, and the ovum waits for the sperm in the fallopian tube. At the same time, the endometrium grows in the uterus in preparation for the implantation of a fertilized egg. The endometrium thickens in response to estrogen (a hormone secreted before ovulation), and when implantation does not occur, the endometrium is shed from the uterus, which is the start of a period.
Some factor in menstrual blood that flows back through the fallopian tube is thought to be involved in the development of endometriosis, although this is not yet clear. In addition, an increase in estrogen secretion induces the growth of both endometrium and endometriotic tissues. Compared with older generations, modern women experience earlier menarche, tend to get married later or give birth later to fewer children, and experience menopause later. This means that they experience more periods in their lifetime and also that in turn regurgitation of menstrual blood and secretion of estrogen occur more frequently, resulting in a higher risk of endometriosis.

Symptoms and signs of endometriosis vary but are generally characterized by severe pain and infertility. Deep endometriosis, which develops deep in the abdomen, induces particularly severe pain, and some patients have pain with intercourse or bowel movements. Furthermore, various disorders caused by endometriosis, e.g., ovulation and fertilization disorders, make it difficult to get pregnant. Indeed, 25-50% of infertile patients have endometriosis.

Treatment for endometriosis consists of medication (hormone therapy) and surgery. Selection of the treatment depends on disease severity and when a patient wishes to become pregnant. In general, hormone therapy is used to relieve symptoms in patients with mild or early endometriosis. In patients with severe endometriosis, surgery is performed and followed by hormone therapy to prevent recurrence. Hormone therapy is provided first to reduce the lesion before surgery in some patients, depending on their conditions. Since endometriosis is likely to recur, patients need to continue hormone therapy except for a time frame in which they wish to become pregnant.

Most women tend to think that they should endure menstrual pain, but abnormal pain is an important alert for a disease. You should pay attention to a change in pain, and you should visit a gynecologist immediately if you notice any unusual condition. A condition in which menstruation-related symptoms are so severe as to interfere with your activities of daily living is called dysmenorrhea. Dysmenorrhea may develop into endometriosis. Since endometriosis is a chronic and progressive disease, it is important to start medication, including hormone therapy, at the stage of dysmenorrhea to prevent the progression to severe endometriosis requiring surgery.