Endometriosis and adenomyosis are separate conditions with many similarities. Both diseases involve abnormalities of the tissue that lines the uterus — the endometrium. In endometriosis, tissue resembling the endometrium spreads outside the uterus, causing inflammation, implants, and adhesions on the organs and surfaces of the pelvic cavity. In adenomyosis, endometrial tissue remains within the uterus, but infiltrates the muscular walls of the womb and grows in pockets within the wall.

It is not uncommon to have both adenomyosis and endometriosis at the same time. Approximately 40 percent to 50 percent of women with adenomyosis also have endometriosis.

How To Tell the Difference Between Adenomyosis and Endometriosis

The easiest way to describe the difference between the diseases is that adenomyosis is only inside the uterus, while endometriosis is only outside the uterus.

While endometriosis is most common in women of childbearing age and is frequently diagnosed in women who have not given birth, adenomyosis typically develops in women in their 40s and 50s who have had children. It is possible that adenomyosis may be present in younger women, but not detected as often. Endometriosis is estimated to occur in 7 percent of women of reproductive age in the U.S., while adenomyosis is found in about 25 percent.

Symptoms of Adenomyosis and Endometriosis

Endometriosis and adenomyosis share many symptoms, including intensely painful menstrual periods. Like endometriosis, adenomyosis can also cause pain during sexual intercourse. Women with adenomyosis experience unusually heavy menstrual flow, while fertility is negatively impacted for women with endometriosis. In uncontrolled, retrospective studies, endometriosis has been associated with an increased rate of miscarriage — up to 40 percent compared with a baseline normal rate of 15 percent to 25 percent. Adenomyosis is not known to increase the risk of miscarriage. Both conditions may also cause abdominal bloating.

Read more details about endometriosis symptoms.

Causes of Adenomyosis and Endometriosis

The root causes of endometriosis and adenomyosis are unknown. Risk factors for endometriosis include genetic and immunologic factors. Risk factors for adenomyosis are different than those for endometriosis. Risk factors for adenomyosis include being middle-aged, having given birth, and having undergone invasive uterine surgery such as a cesarean section (C-section) or fibroid removal.

Read more details about endometriosis causes and risk factors.

Diagnosis of Adenomyosis and Endometriosis

Adenomyosis may be suspected after a pelvic exam showing an enlarged, boggy, and tender uterus. The doctor may perform ultrasound and magnetic resonance imaging (MRI) scans or take a biopsy of endometrial tissue to check for signs of adenomyosis. However, a confirmed diagnosis of adenomyosis is only possible after hysterectomy (removal of the uterus) and laboratory examination of the tissue.

Endometriosis is diagnosed by laparoscopy. In many women with endometriosis, no abnormality is detected during the pelvic exam. Laparoscopy can show the characteristic “powder burn” lesions on the surface of the peritoneum (the membrane lining the abdominal cavity). If the doctor suspects endometriosis, these lesions can be biopsied to confirm the diagnosis. As many as 24 percent of lesions thought to be endometriosis can turn up to be negative. Read more details about endometriosis diagnosis.

Treatment of Adenomyosis and Endometriosis

Like endometriosis, adenomyosis symptoms may improve with hormonal treatment. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as Advil (Ibuprofen), and fibrinolysis inhibitors, such as Lysteda (Tranexamic acid), may be taken to ease pain, inflammation, and menstrual flow.

When family planning is complete, adenomyosis can be cured by hysterectomy. Endometriosis symptoms may or may not improve with hysterectomy. Removal of both ovaries at the time of hysterectomy is often recommended in women with endometriosis. Medical treatment with anti-estrogen therapy is often needed to provide long-term relief for endometriosis patients who still have their ovaries. Symptoms from both endometriosis and adenomyosis typically disappear after menopause.

Read more details about endometriosis treatments.

Condition Guide

• What Is Endometriosis?
• Endometriosis — The Path to Diagnosis
• Stages of Endometriosis
• Symptoms of Endometriosis
• Treatments for Endometriosis
• What Causes Endometriosis?