Adenomyosis is a medical condition in which ectopic (out of place) glandular tissue like that of the uterine lining (endometrium) is present within the muscle body of the uterus (womb). The word adenomyosis comes from adeno- (Greek prefix meaning gland) and prefix myo- (meaning muscle), and -osis (meaning condition). The old-fashioned term was endometriosis interna.

Adenomyosis is a different condition from endometriosis and these two diseases are only found together in about 10% of the cases. Adenomyosis usually refers to tissue which is similar to endometrial tissue (the inner lining of the uterus) lying within the myometrium (the thick, muscular wall of the womb). The word "adenomyometritis" specifically means that the tissue is inflamed within the uterus.

The problem is typically found in women between the ages of 30 and 50. Although, occasionally young women do develop adenomyosis. The symptoms which are most common with adenomyosis are: painful periods (dysmenorrhoea) and/or heavy menses (menorrhagia). However, because the endometrial glands can become trapped within the myometrium, sometimes women experience pelvic pain without increased bleeding. This symptom pattern can suggest a diagnosis of adenomyosis rather than endometrial hyperplasia; in the latter condition, menorrhagia is more frequent.

In adenomyosis the inner endometrium penetrates into hyperplastic muscle fibres. Therefore, unlike the functional endometrium, basal layer does not undergo typical cyclic changes with the menstrual cycle.

Adenomyosis may involve the uterine body in a focal way creating an adenomyoma. With diffuse involvement, the uterus becomes larger and on pelvic bimanual examination is found to be 'bulky' and heavier than normal.

Adenomyosis and endometriosis can co-exist.

It is also possible to have uterine fibroids and adenomyosis together, but this is unusual. Adenomyosis pain tends to be more severe than fibroid pain.

Diagnosis

Adenomyosis can be difficult to diagnose because the abnormal tissue lies within the muscle of the uterus between in the inner and outer walls of the uterus. Tests performed during investigation for adenomyosis:

Ultrasound scan

A pelvic ultrasound performed using a probe in the vagina with a high quality ultrasound machine may reveal a pattern of mottling in the uterine wall. This is often described by radiologists as “rain in the forest” appearance. However, most ultrasound scans are normal. If the adenomyosis has formed in a round lump in the muscle wall then it is known as an adenomyoma, and may look like a fibroid during an ultrasound scan. Fibroids nearly always show up on an ultrasound scan.

Hysteroscopy

This is a surgical procedure or investigation which involves the inspection of the uterine cavity with an endoscope via the vagina and the cervix. It enables the diagnosis of intrauterine pathology and serves as a method for surgical treatment if required. With adenomyosis a hysteroscopy is usually normal but sometimes tiny gland openings will be observed.

Laparoscopy

This enables the pelvic organs and outside of the uterus to be visualised. This usually normal as well, but occasionally will show and uneven texture in a bulky uterus. The main benefit of a pelvic laparoscopy is to exclude other causes of pelvic pain such as endometriosis, ovarian pathology or adhesions.

Histology

This is the only reliable way to diagnose adenomyosis. Histological diagnosis involves taking a sample of tissue, in this case a piece of the uterus, and examining it under the microscope. This is only possible after the uterus has been removed during a hysterectomy. It means some women will decide to have a hysterectomy for their symptoms of heavy periods, fibroid pain or pelvic pain without knowing whether they have adenomyosis or not.

Treatment

This depends on a woman’s priorities. Deciding on a treatment plan involves reviewing all your symptoms, your plans for future pregnancy and your personal preference. The treatment options are:

• No treatment. Adenomyosis is not a life threatening condition and therefore this may be the preferred option.
• A levonorgestrel releasing intra-uterine device (IUD). This type of IUD makes menstrual periods lighter and sometimes improves pelvic pain or period pain. If it does not suit a woman, once tried, then it can easily be removed.
• Progestogen tablets or progestogen injection to stop periods.
• Anti-prostaglandin medication such NSAIDS e.g. ibuprofen or mefenamic acid.
• Danazol in a low dose of 200mg daily. Danazol works by inhibiting ovarian steroidogenesis (steroid hormone production) which results in reduced secretion of estradiol by the ovaries. It may also increase androgen (testosterone) levels. Pituitary hormones are largely unaffected by danazol although luteinizing hormone (LH) may be slightly elevated. The side effects of danazol due to higher androgen levels include: weight gain, slightly bulkier muscles, oily skin, increased body hair and muscle cramps. The side-effects due to low estrogen levels include reduced libido (interest in sex), smaller breasts and sometimes hot flushes. In addition there may be deepening of the voice. The voice deepening is not common but may be irreversible, whereas the other side effects resolve once the danazol is stopped. Danazol is a banned substance for competitive athletes. This is because it increases muscular strength. It may also cause a rise in blood sugars and should be taken with care by women who are diabetic. It is extremely important not to fall pregnant whilst taking danazol because it may result in abnormalities of a baby’s genital organs. Danazol is only a short term treatment for adenomyosis and is not a popular choice because of its problematic side effects. 
• The combined contraceptive pill. This is taken continuously to avoid periods. It is best to take a contraceptive pill that is progesterone dominant i.e. one that is relatively low in estrogen and higher in progesterone.
• Laparoscopic surgery can be used to remove an adenomyoma. This is only an option if the adenomyosis lies together in an easily found lump. The surgical procedure can be performed laparoscopic ally but it is a much more difficult operation than a hysterectomy.
• Natural therapies. These aim to reduce estrogen dominance and to make the adenomyosis less active. This is a large subject and will be covered in a forthcoming article or articles about natural treatments for fibroids, endometriosis and adenomyosis.
• Hysterectomy. The majority of women with adenomyosis are over 35 and many will have no plans for further pregnancy. They may also have other uterine conditions such as fibroids. For these women a hysterectomy can be a sensible choice. Obviously hysterectomy is not a suitable for younger women or those planning a future pregnancy.

If a woman is of an age where the menopause is close, then she may decide to wait because adenomyosis usually resolves after the menopause because of lower estrogen levels. For most women their symptoms disappear or improve considerably after the menopause. However if a woman takes HRT after the menopause , then her estrogen levels do not fall and the adenomyosis is likely to continue to cause symptoms.