by EBSCO Medical Review Board


Endometrial tissue is normally found in the uterus. Endometriosis is when this type of tissue is found outside the uterus on the organs in the belly or pelvis. Endometrial tissue thickens and sloughs off when estrogen is present. It leaves the body during menstruation.

Tissue that forms outside of the womb will also thicken due to estrogen changes. However, it cannot pass out of the body during menstruation. This causes swelling and scarring in the belly and pelvis.

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The cause of endometriosis is not known. It may be due to:

  • Menstrual tissue that backs up through the fallopian tubes and spills into the belly
  • Immune system that does not stop tissue from implanting on other organs
  • A lymph system that carries cells from the uterus
  • Surgery that accidentally relocates cells

Risk Factors

Endometriosis is more common in women of reproductive age. Other things that may raise the risk are:

  • Menstruating before the age of 10 years old
  • Having a cycle of less than 28 days
  • Having a flow of more than 5 to 6 days
  • Having an abnormal reproductive tract
  • Not having children


Some people do not have problems. Others may have mild to severe problems, such as:

  • Cramping and pelvic pain before and during menstrual bleeding
  • Pain during sex and bleeding after
  • Pain during bowel movements or urination
  • Irregular menstrual cycles
  • Pain in the lower back, belly, or pelvis


You will be asked about your symptoms and past health. A pelvic exam will be done.

Images will be taken of the pelvis. This can be done with an ultrasound taken from the outside of the belly. It may also be done with a probe placed in vagina.

Laparoscopy is needed to confirm the diagnosis. A small cut is made in the belly. A scope is passed through the cut. It lets the doctor look for problem areas in the belly area. A sample of tissue may be taken as a biopsy . The sample will be carefully looked at and tested.


Treatment depends on how severe the problems are. The goals are to ease pain and slow tissue growth. Options may be:


Medicine may be given to ease pain and swelling. It may be over-the-counter pain medicine, such as nonsteroidal anti-inflammatory drugs (NSAIDs).

Hormone medicine like birth control pills may also help. Birth control pills may be used to ease pain and shrink the size and number of growths. These problems often return when the pills are stopped. They will need to be stopped if a pregnancy is desired.

An intrauterine device (IUD) may be used in those who are not helped by birth control pills.


Some growths can get in the way of future pregnancy. Surgery may be done to remove those growths.

Surgery may also be done for severe symptoms that do not respond well to other treatment. The goal will be too remove as much problem tissue as possible. The tissue can grow back later. Hormone therapy may be used after surgery to lower the chance of growths coming back.


There are no steps to prevent endometriosis.


Endometriosis Association 

The American College of Obstetricians and Gynecologists 


The Society of Obstetricians and Gynaecologists of Canada 

Women's Health Matters 


American College of Obstetricians and Gynecologists (ACOG). Practice bulletin no. 114: management of endometriosis. Obstet Gynecol. 2010 Jul;116(1):223-36, reaffirmed 2018.

Endometriosis. ACOG website. Available at: Updated January 2019. Accessed January 14, 2020.

Endometriosis. EBSCO DynaMed website. Available at:  . Updated August 30, 2019. Accessed January 14, 2020.

Endometriosis. Office on Women's Health—US Health and Human Services website. Available at: Updated April 1, 2019. Accessed January 14, 2020.

Levine EM, et al: Deep Infiltrating Endometriosis: Making the Diagnosis. J Diagn Med Sonogr 2019;35(4):1-3.

Practice bulletin no. 114: management of endometriosis. Obstet Gynecol. 2010;116(1):223-236. Reaffirmed 2016.

2/12/2018 DynaMed Systematic Literature Surveillance  : Guerriero S, Saba L, et al. Transvaginal ultrasound (TVS) versus magnetic resonance (MR) for diagnosing deep infiltrating endometriosis: a systematic review and meta-analysis. Ultrasound Obstet Gynecol. 2017 Nov 20.

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