Endometriosis vs adenomyosis: what's the difference?

Bottom lineBoth involve uterine-lining-like tissue in the wrong place, but endometriosis grows outside the uterus (causing pelvic pain, painful sex, and infertility, at any reproductive age) while adenomyosis grows into the uterine muscle wall (causing very heavy periods, severe cramping, and an enlarged uterus, more often in the 30s and 40s); they can coexist, are diagnosed by symptoms and imaging, and adenomyosis can be definitively treated by hysterectomy when childbearing is complete.

Both involve uterine-lining-like tissue in the wrong place and can cause painful, heavy periods, but the location differs - and so does some of the treatment.

Endometriosis

• Tissue similar to the uterine lining grows outside the uterus (ovaries, tubes, pelvic organs)
• Causes pelvic pain, painful periods, pain during sex, bowel/bladder symptoms, and is a common factor in infertility
• Can occur at any reproductive age, including the teens and twenties

Adenomyosis

• Uterine-lining-like tissue grows into the muscular wall of the uterus itself
• Causes very heavy periods, severe cramping, and an enlarged, tender uterus
• More commonly diagnosed in people in their 30s and 40s, often after childbirth

Key differences

• Location: endometriosis is outside the uterus; adenomyosis is within the uterine muscle
• Hallmark: endometriosis leans toward pelvic pain and infertility; adenomyosis toward heavy bleeding and cramping
• They can coexist

Diagnosis and treatment

Both are diagnosed through symptoms and imaging (ultrasound/MRI). Treatments overlap (hormonal options, pain management), but adenomyosis is within the uterus, so hysterectomy can be a definitive option when childbearing is complete.

See what is adenomyosis and our conditions comparison.

Femora helps you track pain and bleeding patterns that help distinguish these conditions.