Adenomyosis

Summary

Adenomyosis is a benign condition where endometrial tissue grows within the myometrium, causing uterine enlargement, heavy bleeding, and dysmenorrhea, with localized forms called adenomyomas. It mainly affects multiparous women aged 40–50, often linked to prior uterine surgery. Diagnosis is best made with MRI; treatment ranges from NSAIDs and hormonal therapy (especially LNG-IUS) to interventional procedures, with hysterectomy as the definitive cure. Symptoms typically resolve after menopause.

Definition

Adenomyosis is a benign gynecological condition characterized by the presence of functional endometrial glands and stroma within the myometrium, at least 2.5 mm below the endometrial–myometrial junction. This ectopic tissue undergoes cyclic bleeding, causing hypertrophy and hyperplasia of surrounding smooth muscle, resulting in diffuse or focal uterine enlargement. When localized, it forms a nodular lesion termed an adenomyoma.

Epidemiology & Risk Factors

Prevalence: Found in 20–40% of hysterectomy specimens, most often in multiparous women aged 40–50.

Risk factors:

• High parity

• Prior uterine surgery (dilation and curettage, cesarean section, endometrial ablation)

• Elevated estrogen exposure (e.g., early menarche, obesity)

• Possible genetic predisposition.

Common coexistence: Fibroids (50–60%) and endometriosis (15–20%).

Pathophysiology

Adenomyosis develops when functional endometrial glands and stroma infiltrate the myometrium, usually due to disruption of the endometrial–myometrial junction (junctional zone). This disruption can result from mechanical trauma (e.g., uterine surgery, cesarean section, curettage) or chronic micro-injuries over time. Once embedded in the myometrium, the ectopic endometrial tissue remains hormonally responsive: it proliferates and bleeds cyclically, triggering smooth muscle hypertrophy, hyperplasia, and local inflammation.

Clinical Features

• Asymptomatic: ~30% of cases

• Symptomatic

• Heavy menstrual bleeding (menorrhagia): ~50% of symptomatic cases

• Secondary dysmenorrhea: ~30%

• Deep dyspareunia, chronic pelvic pain, or infertility (less common)

• On examination, the uterus is symmetrically enlarged, soft, and tender, usually <14 cm in size.

Differentiation from Similar Conditions

Investigations

• Pelvic ultrasound: May reveal globular uterine contour, heterogeneous myometrium, myometrial cysts, and poor endometrial–myometrial interface definition.

• MRI: gold standard, most accurate.

• Junctional zone thickness >12 mm is diagnostic hallmark finding)

• Presence of small high-signal foci within the myometrium on T2-weighted images.

• Definitive diagnosis: Histological confirmation after hysterectomy.

Management

1. Medical (first-line for symptom control):

• NSAIDs for dysmenorrhea.

• Hormonal therapies:

• Combined oral contraceptives (cyclic or continuous)

• Oral or injectable progestins

• LNG-IUS – most effective non-surgical option

• GnRH agonists or aromatase inhibitors (short-term due to side effects)

2. Interventional (uterine-sparing options):

• Uterine artery embolization (UAE)

• Endometrial ablation or resection (less effective in diffuse disease)

• MRI-guided focused ultrasound (HIFU)

3. Surgical:

• Hysterectomy – definitive and curative in women who have completed childbearing.

• Adenomyomectomy may be considered in focal disease for fertility preservation.

Prognosis

Symptoms usually resolve after menopause due to decreased hormonal stimulation. Untreated adenomyosis can significantly impact quality of life due to chronic pelvic pain and menorrhagia.