Adenomyosis is a benign uterine disease in which endometrial tissues (glands and stroma) are found within the myometrium (wall of the uterus). It has been described as endometriosis interna. In a normal menstrual cycle, the endometrial tissue will grow, becomes thicken, and then shed, resulting in the expected cyclical or monthly menstrual bleeding. If this happens in the uterine wall (myometrium), the resulting bleeding in the wall will cause pain and in the long term, the uterine wall will progressive thicken, thus produces a diffusely enlarged uterus.
The cause of such growth in the uterine wall is not known. It may be related to repeated childbirths, pelvic endometriosis, increasing age, and late childbirth. There is an increased association of pelvic endometriosis and adenomyosis in about 30% of cases. Other diagnoses commonly found in women with adenomyosis include fibroids and endometrial polyps.
The exact incidence of the disease is unknown. It is generally estimated that 20% of women have adenomyosis. It is likely to be higher, due to the fact that many women are now delaying childbirth till a much later age.
Clinical symptoms and signs
Some women with adenomyosis are asymptomatic and diagnosis is only made on histological examination of the uterus.
Typical symptoms of adenomyosis are:
- Heavy menstrual bleeding – this is due to increased uterine cavity bleeding surface area as a result of enlargement and inadequate uterine contraction.
- Dysmenorrhea (menstrual pain) – the pain is usually severe and can be prolonged. The pain usually coincides with the timing of excessive menstrual flow. In some women, the pain may persist even after cessation of menses and present as chronic pelvic pain.
- Dyspareunia or frequency of urination—are due to the enlarged and tender uterus.
- Infertility: Women with adenomyosis have a higher incidence of infertility and miscarriage.
The examination may reveal:
- Tenderness in the lower abdomen during menses
- Enlarged uterus which is palpable per abdomen
- Anaemia due to excessive menstrual bleeding
Picture showing the uterine enlargement due to adenomyosis. The red patches represent the endometrial tissue which bleeds during every menstrual cycle.
The diagnosis of adenomyosis can only be confirmed via microscopic examination of the uterine specimen taken from a hysterectomy. The diagnosis is suspected from clinical history, examination, and imaging scans. Ultrasound scan of the pelvis will show mixed echogenicity in the uterine wall. The uterine wall is typically thickened and more commonly in the posterior wall. These findings may be confused with fibroids and they may also co-exist. The more accurate imaging modality is the Magnetic Resonance Imaging (MRI). It is more specific to the diagnosis and will be able to differentiate adenomyosis from fibroids.
The only definitive treatment for adenomyosis is total hysterectomy (removal of the uterus), with or without ovarian conservation. Some women may respond to medical therapy but eventually, the majority will need a hysterectomy for cure. Therefore, early diagnosis is important because women with early adenomyosis respond better to medical therapies.
1. Medical therapies
- Tranexamic acids – this is given for the reduction of heavy menstrual flow and to be taken at the start of menstrual bleeding. It may help to relieve period pain as well if there is a reduction of menstrual flow.
- Painkillers – usually the non-steroidal anti-inflammatory drugs (NSAIDs) are the first choice such as mefenamic acid, diclofenac, ibuprofen and naproxen. For those who cannot tolerate it due to gastric side effects, COX-2 inhibitor such as celecoxib (Celebrex) or etoricoxib (Arcoxia) tablets can be taken.
- Birth control pills – combined oral birth control pills can be used if there is an additional need for contraception. This can help in the reduction of menstrual flow and period pain. It is best if taken continuously for several packs before a break (pill-free interval). This extended regime will reduce the number of menstrual bleeds in a year.
- Progestogen – progestogen is used for endometriosis but can be prescribed in adenomyosis as empirical therapy. Progestogen will offer relief if it can reduce or even stop menstrual flow in women with adenomyosis. There are several types of progestogens in the market, either as an injection every 2 to 3 months or as a daily oral pill. Their effectiveness is the same and differs only in their tolerability and side effects.
- Intrauterine system (MIRENA) – Mirena is a hormonal intrauterine device (IUD) that releases a progestogen and can be used for contraception. The device is a T-shaped plastic frame that is inserted into the uterus and lasts for 5 years. The progestogen release will suppress or reduce the menstrual bleeding and will help in improving pain and anaemia. However, Mirena will not be suitable for those who presented late with an enlarged uterus. The Mirena will not fit well in an enlarged uterine cavity and the response will be poor. The expulsion rate is also higher.
Regular follow-up is required to assess response to therapy and to monitor the uterus size via clinical examination and an ultrasound scan of the pelvis. Increasing pain and heavier menstrual flow with worsening anaemia suggest a failure of medical therapies and are an indication for surgery.
2. Uterine artery embolization (UAE) – has been offered in some centers for the treatment of symptomatic adenomyosis. It is a minimally invasive option to stop the main blood supply to the uterus. It is effective for those nearing perimenopausal age. For younger patients, there is a higher rate of symptom recurrence.
3. Surgery – Hysterectomy (removing the uterus) is often the best option for cure. Oophorectomy (removal of the ovaries) at the same time is not required unless otherwise indicated.
(Revised 27 December 2021)