Adenomyosis is a medical condition characterised by the abnormal presence of endometrial tissue within the myometrium, leading to thickening of the uterus. Endometrial tissue in adenomyosis behaves normally by thickening, shedding, and bleeding with each menstrual cycle.

This condition is predominantly found in women aged 35-50 but can also affect younger women. It often presents with painful and heavy menstrual bleeding, pain during sexual intercourse, chronic pelvic pain, and bladder irritation.

Adenomyosis uteri seen during laparoscopy: soft and enlarged uterus; the blue spots represent subserous endometriosis.

Signs and Symptoms

Adenomyosis manifests variably, from being asymptomatic to causing severe symptoms. Women typically report symptoms between 40 and 50 years of age. Common symptoms include heavy menstrual bleeding, which can lead to anaemia, chronic pelvic pain, painful menstruation, painful intercourse, and feelings of pelvic fullness. Clinical signs include uterine enlargement, tenderness, and sub-fertility. Women with adenomyosis are also more likely to have uterine fibroids, endometriosis, and endometrial polyps.

Causes

The exact cause of adenomyosis is unknown but is associated with uterine trauma that disrupts the junctional zone between the endometrium and myometrium, such as from caesarean sections or surgical pregnancy terminations. Hormonal factors, such as local hyperestrogenism, elevated s-prolactin levels, and autoimmune factors, may also contribute. The Tissue Injury and Repair (TIAR) theory suggests that hyperperistalsis during early reproductive life induces micro-injury at the endometrial-myometrial interface, leading to elevated local oestrogen and subsequent biological alterations essential for adenomyosis development.

Mechanism

Pathophysiology

Cross section through the wall of a hysterectomy specimen of a 30-year-old woman who reported chronic pelvic pain and abnormal uterine bleeding.

Misplaced endometrial tissue in the myometrium causes symptoms via increased prostaglandin production, leading to painful uterine contractions. Oestrogen drives endometrial proliferation, contributing to heavy menstrual bleeding due to increased tissue and vascularisation, atypical contractions, and elevated prostaglandins, oestrogen, and eicosanoids.

Histopathology

Diagnosis is confirmed by microscopic examination of uterine tissue samples, revealing invading clusters of endometrial tissue within the myometrium. Diagnostic criteria typically require endometrial tissue to invade more than 2% of the myometrium or a minimum invasion depth of 2.5 to 8mm.

Histopathological image of uterine adenomyosis observed in hysterectomy specimen. Hematoxylin & eosin stain.

Diagnosis

Imaging

Non-invasive imaging techniques like transvaginal ultrasonography (TVUS) and magnetic resonance imaging (MRI) are used to suggest adenomyosis, guide treatment, and monitor response. TVUS, with a sensitivity of 79% and specificity of 85%, is defined by characteristics like myometrial cysts, hyperechogenic islands, echogenenic subendometrial lines, and indirect features like an enlarged uterus and fan-shaped shadowing.

Transvaginal ultrasound of the uterus, showing the endometrium as a hyperechoic (brighter) area in the middle, with linear striations extending upwards from it.

MRI has a sensitivity of 74% and specificity of 91% for adenomyosis detection, focusing on the thickened junctional zone with diminished signal on weighted sequences.

Sagittal MRI of a woman's pelvis showing a uterus with adenomyosis in the posterior wall. Gross enlargement of the posterior wall is noted, with many foci of hyperintensity.

Treatment

Medications

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for pain relief. Hormonal treatments like levonorgestrel-releasing intrauterine devices (IUDs), oral contraceptives, progesterone, and gonadotropin-releasing hormone (GnRH) agonists help manage symptoms by reducing endometrial tissue growth and menstrual bleeding.

Surgery

Surgical management includes uterine-sparing procedures like uterine artery embolisation (UAE), myometrium resection, and MRI-guided focused ultrasound surgery, which aim to reduce adenomyosis symptoms while preserving fertility. Endometrial ablation techniques, suitable for those not wanting future pregnancies, include radiofrequency ablation, thermal balloon, and cryo-endometrial ablation.

Non-uterine-sparing procedures, primarily hysterectomy, offer definitive treatment but result in sterility. Various hysterectomy techniques include laparoscopic, robotic, vaginal, and abdominal approaches.

Epidemiology

Adenomyosis affects 20 to 35% of women, often progressing over time, but does not increase cancer risk. It is more common in those with uterine fibroids or endometriosis.

Fertility

Adenomyosis can cause infertility, but hormonal therapies may improve fertility. Women with adenomyosis undergoing in-vitro fertilisation (IVF) have lower pregnancy and higher miscarriage rates. Screening for adenomyosis before assisted reproduction treatments is recommended.

Self-assessment MCQs (single best answer)

What is adenomyosis primarily characterised by?

score 0 / 1. running total: 0 / 0

Which age group is predominantly affected by adenomyosis?

score 0 / 1. running total: 0 / 0

Which of the following is NOT a common symptom of adenomyosis?

score 0 / 1. running total: 0 / 0

What diagnostic method is used to confirm adenomyosis through microscopic examination?

score 0 / 1. running total: 0 / 0

What is the sensitivity and specificity of transvaginal ultrasonography (TVUS) for diagnosing adenomyosis?

score 0 / 1. running total: 0 / 0

What is the primary hormonal factor associated with the development of adenomyosis?

score 0 / 1. running total: 0 / 0

Which surgical treatment for adenomyosis is non-uterine-sparing and results in sterility?

score 0 / 1. running total: 0 / 0

What theory suggests that hyperperistalsis during early reproductive life induces micro-injury at the endometrial-myometrial interface?

score 0 / 1. running total: 0 / 0

Which non-invasive imaging technique has a sensitivity of 74% and specificity of 91% for detecting adenomyosis?

score 0 / 1. running total: 0 / 0

Which of the following medications is commonly used for pain relief in adenomyosis?

score 0 / 1. running total: 0 / 0