What is Adenomyosis
Adenomyosis is a benign uterine disorder where endometrial glands and stromal tissue are pathologically present within the myometrium (uterine muscle layer), causing the myometrium to undergo hyperplasia and hypertrophy. 1
Pathological Definition
Adenomyosis represents endometrial-like tissue located abnormally within the myometrium, characterized by endometrial epithelial cells and stromal fibroblasts embedded in the muscle wall where they trigger surrounding smooth muscle cell proliferation and enlargement. 2
The condition is distinct from endometriosis, though it is sometimes classified as a specific subtype in certain deep endometriosis classification systems; however, adenomyosis remains a separate clinical entity. 3
The gold standard histopathological definition remains controversial, with poor inter-observer reproducibility in limited disease, leading to significant variations in reported disease prevalence. 1
Clinical Characteristics
Adenomyosis is an estrogen-dependent disease that presents with a wide spectrum of manifestations, from completely asymptomatic to severe symptoms including dysmenorrhea (painful menstruation), heavy menstrual bleeding (HMB), chronic pelvic pain, dyspareunia, and infertility. 4, 5
The disease causes uterine enlargement and is associated with inflammation, fibrosis, neurogenesis, and angiogenesis within both endometrial and myometrial components. 2
Adenomyosis frequently coexists with other gynecological conditions, particularly endometriosis and uterine fibroids, which complicates the diagnostic process. 1
Pathophysiological Mechanisms
The development of adenomyosis likely involves multiple pathogenic pathways: 2
- Microtrauma at the endometrial-myometrial interface with enhanced invasion of endometrium into myometrium
- Metaplasia of stem cells within the myometrium
- Inside-to-outside invasion from the endometrial side into the uterine wall
- Outside-to-inside invasion from the serosal side (via retrograde menstrual effluent infiltration)
- Epithelial-mesenchymal transition with tissue remodeling
- Aberrant local steroid hormone signaling with progesterone resistance
Diagnostic Approaches
Transvaginal ultrasound can diagnose adenomyosis with sensitivity of 82.5% and specificity of 84.6%. 3
MRI provides superior visualization of the endometrium even when adenomyosis is present, which may be obscured on ultrasound. 3
An integrated diagnostic approach is recommended, combining risk factor assessment, clinical symptoms, physical examination findings, and imaging (2D/3D ultrasound or MRI) to identify both diffuse and focal phenotypes of adenomyosis. 1