Endometriosis is when the tissue that lines the uterus (womb) grows outside of it. Common places it may grow are the ovaries, fallopian tubes, and pelvis.
The tissue is part of the menstrual cycle. Hormones cause it to swell, break down, and bleed. It will also do this when it grows outside of the uterus. This causes pain and problems getting pregnant.
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Brown R, Byrne D, et al. National Institute for Health and Care Excellence (NICE) guideline NG73. Endometriosis: diagnosis and management. National Guideline Alliance (UK). NICE 2017 Sep.
Endometriosis. ACOG website. Available at: https://www.acog.org/Patients/FAQs/Endometriosis. Updated January 2019. Accessed November 12, 2019.
Endometriosis. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/endometriosis. Updated August 30, 2019. Accessed November 12, 2019.
Endometriosis. Office on Women's Health website. Available at: https://www.womenshealth.gov/a-z-topics/endometriosis. Updated April 1, 2019. Accessed November 12, 2019.
Last reviewed September 2019 by
EBSCO Medical Review Board
Elliot M. Levine, MD, FACOG
Last Updated: 11/17/2020