Adenomyosis: Symptoms, Diagnosis, Effect on Pregnancy and Treatment

What is adenomyosis?

The uterus has three layers: the inner lining that is shed each month with the period (the endometrium), the thick muscular wall (the myometrium) and an outer covering. In adenomyosis, glands from the inner lining and their supporting tissue (stroma) are found within the muscular wall of the uterus.

This tissue within the muscle also responds to hormones through the menstrual cycle. The surrounding muscle thickens, the uterus may gradually become enlarged and rounded, and it may become tender and painful during periods. Adenomyosis is a benign condition and is not cancer.

Diffuse and focal adenomyosis

• Diffuse adenomyosis: the condition is spread through a large part of the muscular wall. The uterus is generally enlarged, and the front and back walls often differ clearly in thickness (asymmetry).
• Focal adenomyosis and adenomyoma: the condition is concentrated in a limited area of the wall. When it forms a rounded mass together with the surrounding muscle, it is called an adenomyoma; it can look similar to a fibroid.

How is adenomyosis different from fibroids and endometriosis?

These three conditions can cause similar symptoms and are often confused, but they are different:

• Fibroids: benign tumours that grow from uterine muscle cells and are separated from the surrounding tissue by a clear border. A fibroid can often be shelled out of the surrounding tissue, whereas adenomyosis spreads into the muscular wall without a clear border and is difficult to separate in this way.
• Endometriosis: tissue similar to the uterine lining is found outside the uterus, for example on the ovaries or the lining of the pelvis. In adenomyosis, this tissue is within the uterus's own muscular wall.

These conditions often occur together. Many women with endometriosis also have adenomyosis, and fibroids and adenomyosis are not uncommonly found together. For this reason all three are considered during assessment.

Who gets adenomyosis and why?

Adenomyosis has traditionally been described in women aged 40-50 who have had children, because in the past it was usually diagnosed on pathological examination after hysterectomy. With advances in ultrasound and MRI, it is now increasingly recognised in younger women, adolescents and women having difficulty conceiving. Estimates of how common it is vary widely between studies, depending on the diagnostic method and the group studied.

The cause of adenomyosis is not fully understood. The most widely accepted explanation is that the zone between the inner lining and the muscular wall is disrupted, allowing the lining to grow into the muscle. In some studies, previous childbirth and procedures on the uterus such as caesarean section or curettage have been associated with adenomyosis, although these associations have not been shown in every study. The condition is sensitive to oestrogen.

Symptoms

Some women with adenomyosis have no symptoms at all, and the condition is noticed incidentally on an ultrasound done for another reason. When symptoms occur, the most common are:

• Heavy and prolonged periods (menorrhagia), which may lead to iron deficiency and anaemia
• Painful periods (dysmenorrhoea) that may worsen over the years
• Pelvic pain that continues outside periods (chronic pelvic pain)
• Deep pain during sex (dyspareunia)
• A feeling of fullness or pressure in the lower abdomen
• Difficulty conceiving

On examination the uterus may feel larger than normal, soft and rounded, and may be tender, particularly during a period. The severity of symptoms does not always match the extent of disease seen on ultrasound.

How is it diagnosed?

Assessment begins with a detailed history and pelvic examination. Women with heavy bleeding have a blood count to check for anaemia. Other causes of bleeding (polyps, fibroids, thickening of the lining, hormonal disorders) are also considered, and a sample of the lining is taken when needed.

Transvaginal ultrasound

This is the first-line imaging test. The international MUSA (Morphological Uterus Sonographic Assessment) consensus group has defined the ultrasound features that suggest adenomyosis in a common language. They include:

• Uneven thickening of the front and back walls of the uterus (asymmetrical wall thickening) and a rounded, globular uterus
• Small fluid-filled spaces within the muscular wall (myometrial cysts)
• Bright islands within the muscular wall (hyperechoic islands)
• Fine, fan-shaped shadowing in the muscular wall
• An irregular or interrupted junctional zone between the inner lining and the muscular wall, with fine lines and buds extending from the lining into the muscle
• On Doppler, blood vessels passing through the lesion; this helps distinguish adenomyosis from a fibroid, around which vessels typically run

The diagnosis is based on these features taken together rather than on a single finding. Scanning by an experienced clinician with suitable equipment improves accuracy.

MRI

MRI is helpful when ultrasound findings are unclear, when it is difficult to distinguish adenomyosis from fibroids, or when surgery is being planned. The key MRI finding is marked thickening of the junctional zone between the inner lining and the muscular wall; small foci and cysts within the muscle may also be seen.

Pathological examination

A definitive diagnosis is made by examining the tissue under the microscope after the uterus has been removed. Today, however, treatment decisions are usually based on ultrasound and MRI findings, and surgery is not needed for diagnosis.

Treatment

Adenomyosis that causes no symptoms does not need treatment. Treatment is tailored to the type and severity of symptoms, age, wish for pregnancy, whether the disease is diffuse or focal, and any coexisting endometriosis or fibroids. The choice of medication and how long it is used are decided by the doctor.

Medication to reduce pain and bleeding

• Non-steroidal anti-inflammatory drugs (NSAIDs): ease period pain and may also reduce bleeding to some extent. They do not treat the condition itself.
• Tranexamic acid: a non-hormonal medicine taken only on bleeding days that reduces the amount of menstrual blood loss.

Hormonal treatments

• Levonorgestrel-releasing intrauterine system (52 mg hormonal coil): releases hormone locally within the uterus. It can markedly reduce heavy bleeding and period pain and is also an effective contraceptive. For many women it is among the first options.
• Progestogens: progesterone-like medicines such as dienogest can reduce pain and bleeding. Irregular spotting is a common side effect.
• Combined contraceptive pill: can ease symptoms by regulating and lightening periods.
• GnRH analogues: temporarily suppress oestrogen production, shrinking the uterus and reducing symptoms. Because of bone loss and menopause-like side effects they are used for a short time; if longer use is needed, add-back hormone therapy to reduce side effects may be considered.

Hormonal treatments do not remove the condition; they control symptoms, which may return when treatment stops. They are paused when pregnancy is desired.

Uterus-sparing procedures

Adenomyomectomy: in selected women with focal adenomyosis or an adenomyoma who have not benefited enough from medication and wish to keep their uterus, surgical removal of the affected area may be considered. Because adenomyosis has no clear border with the surrounding tissue, this operation is more difficult than fibroid surgery and requires experience. The condition may recur afterwards. There is a risk of the uterine wall tearing (uterine rupture) in later pregnancies, so the timing of pregnancy and the mode of delivery are planned according to the extent of surgery.

Uterine artery embolisation and high-intensity focused ultrasound (HIFU): these methods are used in some centres for selected women who wish to keep their uterus. Although there is evidence that they can reduce symptoms, evidence on long-term outcomes and on later pregnancies is limited.

Hysterectomy

For women who do not wish to have children and have not benefited enough from other treatments, removing the uterus is the definitive treatment that permanently resolves the symptoms of adenomyosis. The operation can usually be done laparoscopically (keyhole) or vaginally; whether the ovaries are kept is discussed separately according to age and other findings. The methods and recovery are described in detail in the separate topic "Hysterectomy".

Does adenomyosis affect fertility and IVF?

Many women with adenomyosis conceive naturally. However, in some studies adenomyosis has been associated with lower embryo implantation rates and a higher risk of miscarriage in IVF. This may be related to changes in the contraction pattern of the uterus and in the receptivity of the lining to an embryo. Because studies differ in their diagnostic criteria and patient groups, the evidence is not consistent.

In couples having difficulty conceiving, adenomyosis is not considered in isolation; age, ovarian reserve, the fallopian tubes, any coexisting endometriosis or fibroids and the partner's semen analysis are assessed together. In IVF, freezing the embryos and preparing with a GnRH agonist for a few months before transfer is considered in some cases, but evidence of benefit is limited and the decision is made individually.

Adenomyosis and pregnancy

Most women with adenomyosis have a healthy pregnancy. In some studies adenomyosis has been associated with preterm birth, pre-eclampsia and the baby being small for gestational age. Careful antenatal care, including blood pressure checks and monitoring of the baby's growth, is therefore recommended for pregnant women with adenomyosis. For women who have had an adenomyomectomy, the birth plan is made after reviewing the details of the operation.

What happens after menopause?

Because adenomyosis is sensitive to oestrogen, symptoms usually settle when hormone levels fall at menopause, and period-related problems come to an end. For women approaching menopause, controlling symptoms with medication until then is therefore sometimes a reasonable option. Any bleeding after menopause, however, should be assessed separately rather than attributed to adenomyosis.

When should you see a doctor?

• Your periods are so heavy that you need to change a pad or tampon every hour for several hours
• You pass large clots or your period lasts longer than a week
• You have symptoms of anaemia such as weakness, tiredness, palpitations, breathlessness or pallor
• Period pain stops you working, studying or carrying out daily activities despite painkillers
• You have pelvic pain outside your periods or pain during sex
• No pregnancy after one year (six months if 35 or over) of regular intercourse
• Any bleeding or spotting after menopause

Frequently Asked Questions

The information on this website is for general information only and does not replace a medical consultation.

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