Describe adenomyosis — its aetiology, clinical features and management.

Definition

Adenomyosis is the presence of endometrial glands and stroma within the myometrium (at least one high-power field below the endo-myometrial junction), with surrounding myometrial hypertrophy. It is sometimes called "internal endometriosis".

Pathology

The uterus is uniformly and symmetrically enlarged (rarely beyond 12 weeks' size) with a thickened, trabeculated myometrium; the cut surface shows whorled muscle with small haemorrhagic cystic spaces. It may be diffuse or, less often, localised (an adenomyoma), and frequently coexists with fibroids and endometriosis.

Clinical Features

— progressively severe

Secondary dysmenorrhoea

And

Menorrhagia

, with a

Uniformly enlarged, bulky, tender uterus

("globular" uterus).

Diagnosis

Transvaginal ultrasound (a heterogeneous, asymmetrically thickened myometrium with cysts) and MRI (a thickened junctional zone) suggest it; the definitive diagnosis is histological after hysterectomy.

Management

• Medical — symptomatic relief with NSAIDs and tranexamic acid; the levonorgestrel-IUS, progestins or GnRH analogues reduce bleeding and pain.
• Definitive — hysterectomy in women who have completed their family and failed medical treatment.

Associations and Investigations

It is associated with multiparity and previous uterine surgery/curettage and commonly coexists with fibroids and endometriosis. On transvaginal ultrasound the myometrium is heterogeneous with cystic spaces, and MRI shows a thickened junctional zone (> 12 mm) — both suggestive but not diagnostic.

A Note on WHY Adenomyosis Gives a Bulky, Tender Uterus

A useful concept is understanding why adenomyosis produces its characteristic clinical picture — and how to distinguish it from a fibroid, which it can closely mimic. In adenomyosis, endometrial glands and stroma are found deep within the myometrium. Because this ectopic endometrium is hormonally responsive, it bleeds into the muscle at each menstruation — causing inflammation, and, with repetition, hypertrophy of the surrounding myometrium. Every feature follows. The uterus becomes diffusely and symmetrically enlarged (typically to about the size of a 12-week pregnancy), globular, soft and — characteristically — tender, especially just before and during menstruation, since it is actively bleeding within itself. The increased endometrial surface and impaired myometrial contraction cause heavy menstrual bleeding (menorrhagia), and the intramyometrial bleeding causes progressively severe secondary dysmenorrhoea. This is precisely the triad: menorrhagia, progressive dysmenorrhoea and a bulky, tender uterus in a multiparous woman in her forties. The contrast with a fibroid is instructive: a fibroid gives a firm, irregular and typically non-tender uterus. MRI (or ultrasound) distinguishes them, but the histology of the removed uterus remains the definitive diagnosis.

Uniformly enlarged tender uterus distinguishes it from fibroid.

• Adenomyosis: endometrial glands and stroma within the myometrium — typically in a multiparous woman in her 40s.
• Triad: menorrhagia + progressive secondary dysmenorrhoea + a diffusely enlarged, globular, soft and tender uterus (about 12 weeks' size).
• Contrast with a fibroid: firm, irregular, non-tender uterus.
• Diagnosis: ultrasound/MRI (a thickened junctional zone) — but definitive diagnosis is histological, after hysterectomy.
• Treatment: LNG-IUS or medical management (progestogens, GnRH agonists) for symptoms; hysterectomy is the definitive cure.