Adenomyosis !
Adenomyosis is a benign condition in which the uterine lining grows into the muscle wall of the uterus, making it enlarged and causing heavy, painful periods.
Updated 2026-10-29
Structures involved
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In histology
Why it happens
What it is
A benign condition in which endometrial glands and stroma grow inside the myometrium, making the uterus enlarged and tender. It typically causes heavy, painful periods.
Who gets it
Most often diagnosed in women in their 40s who have had children, though imaging now finds it in younger women too. It frequently coexists with fibroids and endometriosis.
Causes
- Invagination of the basal endometrium into the myometrium through a disrupted junctional zone
- Metaplasia of embryonic remnants within the myometrium (alternative theory)
- Tissue injury and repair cycles that weaken the endometrial–myometrial border
Risk factors
- Multiparity
- Previous uterine surgery: caesarean section, curettage or myomectomy
- Age 40–50
- Coexisting endometriosis or fibroids
- Longer estrogen exposure (early menarche, short cycles)
Pathophysiology
Endometrial tissue in the myometrium responds to the menstrual cycle, causing micro-bleeding, inflammation and smooth muscle hypertrophy. The uterus becomes globally enlarged and the contractions become abnormal. Increased endometrial surface and impaired contraction add to heavy bleeding.
Classification
- Diffuse or focal
- Adenomyoma: a localised nodular form
- Internal (junctional zone) or external (outer myometrium) patterns on MRI; classification systems vary
Symptoms and signs
- Heavy menstrual bleeding
- Painful periods that worsen over time
- Chronic pelvic pain or pressure
- Pain during intercourse
- Subfertility in some women
- About a third have no symptoms
Diagnosis
- Clinical
- A uniformly enlarged, globular, soft and tender uterus on bimanual examination, often just before or during menstruation.
- Tests
- Pregnancy test; complete blood count and ferritin when bleeding is heavy. Histology of a hysterectomy specimen is the definitive diagnosis.
- Imaging
- Transvaginal ultrasound: asymmetric myometrial thickening, small myometrial cysts, fan-shaped shadowing and a blurred junctional zone. MRI shows a thickened junctional zone (cut-offs vary) and helps separate it from fibroids.
Differential diagnosis
- Uterine fibroids
- Endometriosis
- Endometrial polyp
- Endometrial hyperplasia or cancer
- Primary dysmenorrhoea
Goal of treatment
Reduce pain and bleeding, correct anaemia and, when wanted, preserve fertility.
Treatment
- Medical
- Non-steroidal anti-inflammatory drugs and tranexamic acid for pain and bleeding during menses.
- Medical
- Hormonal therapy: levonorgestrel intrauterine system, progestins, combined hormonal contraceptives or, short term, gonadotropin-releasing hormone analogues.
- Procedure
- Uterine artery embolisation or focused ultrasound ablation in selected women.
- Surgical
- Hysterectomy is the definitive treatment when fertility is not wanted; excision of an adenomyoma is possible in selected cases.
Complications
- Iron deficiency anaemia
- Chronic pelvic pain and reduced quality of life
- Subfertility and adverse pregnancy outcomes
- Uterine rupture risk after extensive excision
Prognosis
Symptoms usually improve after menopause. Medical therapy controls symptoms in many women; hysterectomy cures it.
Test yourself
Think of the answer, then tap the question to see it.
What is adenomyosis?
The presence of endometrial glands and stroma within the myometrium.
What is the classic finding on bimanual examination in adenomyosis?
A uniformly enlarged, globular, soft and tender uterus.
Which two symptoms are most typical of adenomyosis?
Heavy menstrual bleeding and progressively painful periods.
Which imaging test best separates adenomyosis from fibroids?
MRI, which shows a thickened junctional zone and poorly defined lesions, unlike well-circumscribed fibroids.
What is the definitive treatment of adenomyosis?
Hysterectomy, for women who do not wish to become pregnant.
Related conditions
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Adenomyosis (StatPearls (NCBI Bookshelf), 2026).
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