Adenomyosis is a condition where the cells of the uterine lining grow into the muscular wall of the uterus.

Adenomyosis is similar to endometriosis and can cause similar symptoms or no symptoms at all.

Adenomyosis is a relatively widespread condition. The National Health Service (NHS) in the UK estimate that 1 in 10 women have adenomyosis and that it is most common in women aged 40 to 50.

This article gives an overview of adenomyosis, including symptoms, causes, diagnosis, complications, and treatment.

Model of uterus next to stethoscope representing AdenomyosisShare on Pinterest
Adenomyosis may cause similar symptoms to endometriosis.

Adenomyosis is a condition where the cells that usually grow outward into the uterus lining instead grow inward into the uterus muscle.

During a woman's menstrual cycle, these "trapped" cells become stimulated, which can make menstrual cramps and bleeding more severe than usual.

The symptoms of adenomyosis vary throughout the menstrual cycle because of rising and falling levels of estrogen, which affect the shedding of the uterus lining.

Symptoms usually go away or improve after menopause, when a woman's estrogen levels naturally decrease.

Adenomyosis varies widely among people, including the extent of the condition and the severity of the symptoms.

Around one-third of women do not experience any symptoms at all, while for others, symptoms can get in the way of daily life.

Possible symptoms of adenomyosis include:

  • heavy menstrual bleeding
  • very painful periods
  • pain during sex
  • bleeding between periods
  • worsening uterine cramps
  • an enlarged and tender uterus
  • general pain in the pelvic area
  • a feeling that there is pressure on the bladder and rectum
  • pain while having a bowel movement

Doctors are not sure what causes adenomyosis, but there are several theories:

  • Fetal development. Adenomyosis may be present in a person before birth when the uterus first forms in a fetus.
  • Inflammation. Inflammation that occurs in a woman's uterus during uterine surgery could also increase the risk of adenomyosis.
  • Invasive tissue. Injury to the uterus, such as during a cesarean delivery or other surgery, may also cause adenomyosis. This is because the uterus may heal inward toward the muscle, instead of outward.

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Multiple pregnancies may increase the risk of adenomyosis.

Some risk factors that may result in adenomyosis include:

  • Age. Though this condition can affect women of any age, most women diagnosed with adenomyosis are in their 40s and 50s.
  • Pregnancy. A high percentage of women with adenomyosis have had multiple pregnancies.
  • Uterine surgery. Having previous surgery on the uterus, including cesarean delivery, significantly raises the risk of adenomyosis.

Without treatment, adenomyosis may remain the same or symptoms can get worse.

Treatment is not necessary if a woman has no symptoms, is not trying to get pregnant, or is nearing menopause, which is when most women find relief from their symptoms.

However, there are many different treatment options available to women with this condition:

  • Anti-inflammatory medications. Medications such as ibuprofen can reduce pain and discomfort.
  • Hormonal medications. Some hormonal treatments, such as oral contraceptive pills, progestin IUD's, or injection (Depo-Provera), can help lessen the symptoms.
  • Injectable medications. These medications can induce false or temporary menopause. These are only used in the short-term and are not suitable for long-term use.
  • Uterine artery embolization. This involves placing a tube in a major artery in the groin and injecting small particles into the area affected by adenomyosis. This stops the blood supply reaching the affected area, which will shrink the adenomyosis and reduce symptoms.
  • Hysterectomy. The only definitive treatment for adenomyosis is complete removal of the uterus. It is not a good option for women who may still want to become pregnant.

Adenomyosis and endometriosis are very similar, but there are differences.

In adenomyosis, cells lining the uterus grow into the uterus muscle. In endometriosis, these cells grow outside of the uterus, sometimes on the ovaries and fallopian tubes.

These two conditions are equally widespread, though endometriosis occurs more often in women in their 30s and 40s, while more women aged 40 to 50 tend to develop adenomyosis.

It is possible for a woman to have both endometriosis and adenomyosis. The symptoms of both conditions should subside after menopause.

Research suggesting that adenomyosis may have an impact on a woman's fertility is conflicting, as there are often other conditions present in women with fertility issues.

Research into the relationship between adenomyosis, infertility, and pregnancy complications is still ongoing. There are no studies that show an increased risk for miscarriage or other obstetric complications.

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Adenomyosis can sometimes be diagnosed using an ultrasound scan.

Diagnosing adenomyosis begins with a visit to the doctor. The doctor will likely take a medical history and perform a physical and pelvic exam.

A woman will often feel tenderness in her uterus during the pelvic exam. If a doctor thinks that a woman's uterus feels slightly enlarged, and they suspect adenomyosis, the doctor may consider other tests, including:

  • Ultrasound. This allows the doctor to examine pockets of the uterus lining tissue in the muscle of the uterus. However, this can lead to a misdiagnosis, because these pockets can sometimes look like another condition called uterine fibroids.
  • Magnetic resonance imaging (MRI). An MRI scan is the best way for the doctor to see the inner muscle of the uterus.
  • Endometrial biopsy. Sometimes, the doctor will want to take a small sample of the endometrial tissue in the uterus for testing. While it will not help in the diagnosis of adenomyosis, it will rule out other causes of a woman's symptoms.

These testing methods will not give a definite diagnosis, however. It is only possible to definitively diagnose adenomyosis once a woman has had a hysterectomy and a specialized doctor called a pathologist examines the uterus under the microscope.

A woman who is not trying to get pregnant or who is not experiencing any symptoms may not require treatment. However, any woman who suspects adenomyosis or endometriosis should see her doctor for evaluation.

If a woman is experiencing heavy periods or severe uterine cramping, it is essential that she mentions it to her doctor. These symptoms can signal other serious conditions, and it is important that the doctor does tests to determine their cause.

Heavy menstrual bleeding can cause anemia, which is a deficiency of iron. This can make someone feel tired, weak, or run-down and not well. Taking iron supplements can help treat anemia, which can be especially important during menstruation.

The outlook for a woman with adenomyosis is excellent; it is not a life-threatening condition, but it can cause severe discomfort.

A woman should see their doctor if she suspects adenomyosis or endometriosis.

Adenomyosis will go away once a woman reaches menopause. In the meantime, there are some treatments available that can help to alleviate the symptoms.