Fibroids And Adenomyosis: Two Conditions That Often Occur Together

Adenomyosis is frequently confused with fibroids — and just as frequently missed altogether. The two conditions often co-exist, share some symptoms, and require different management approaches. Understanding both is increasingly important.

What Adenomyosis Is

Adenomyosis occurs when endometrial glands and stroma (the tissue that normally lines the uterine cavity) grow into the muscular wall of the uterus (the myometrium). Unlike fibroids — which are discrete growths of smooth muscle — adenomyosis is a diffuse infiltration of the uterine wall. It causes the uterus to become enlarged, soft, and “boggy” on examination, rather than the firm, irregular enlargement of fibroids.

How They Are Similar

Both conditions cause heavy menstrual bleeding and pelvic pain. Both are associated with an estrogen-dominant hormonal environment. Both cause uterine enlargement. Both are most common in women of reproductive age and typically improve after menopause. Both can significantly impair quality of life. These similarities are why the conditions are so often confused — and why they frequently co-exist in the same woman.

How They Are Different

Fibroids are discrete, localised growths visible clearly on ultrasound as separate masses. Adenomyosis is diffuse — the uterus itself is enlarged and the muscle texture is changed, rather than there being separate identifiable masses. Adenomyosis pain tends to be more consistently severe throughout the period rather than clustered around heaviest flow. Adenomyosis is definitively diagnosed only by histology (examining uterine tissue) — ultrasound and MRI can suggest it but not confirm it. MRI is significantly better than ultrasound for detecting adenomyosis.

Why It Matters for Treatment

Myomectomy removes discrete fibroids but does not address adenomyosis — a woman with both conditions who has myomectomy may find that heavy bleeding and pain persist postoperatively because the adenomyosis component was not treated. The Mirena IUD is effective for both conditions. Hysterectomy resolves both. UFE may improve adenomyosis symptoms but less reliably than for fibroids alone.

If you have had fibroid treatment and your heavy bleeding has not improved as expected, or if pelvic pain persists after fibroids have been addressed, asking specifically about adenomyosis — and whether an MRI to evaluate for it has been performed — is appropriate. See our broader treatment comparison at fibroid treatment options.