The endometrium is the lining of the uterus. Endometriosis is caused by endometrium-like cells growing outside the uterus, usually accompanied by inflammation.[1] Researchers haven’t yet pinned down exactly why this happens.[2]
What causes endometriosis?
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•Last Updated: May 16, 2025
Endometriosis occurs when endometrium-like cells grow outside the uterus, which often leads to inflammation. The exact cause of this condition is still not fully understood by researchers.