Endometriosis Causes & Risk Factors
The cause of endometriosis is still widely unknown, but there are ongoing studies to determine it, and several likely theories exist on the subject (the most common is a phenomenon called retrograde menstruation). There are also several risk factors that indicate a higher likelihood of endometriosis developing, including short menstrual cycles and never having given birth. It is important to understand these causes and risk factors to understand whether you might be at risk.
Endometriosis Causes
While researchers are not sure what definitively causes endometriosis, they have identified several possible causes, including1:
- Genetic factors: Endometriosis can often be inherited through genes.
- Hormones: Endometriosis is dependent on estrogen for growth. Researchers are studying whether endometriosis is the result of a problem with the female endocrine system.
- Surgical scar implementation: A surgeon may accidentally pick up and misplace tissue from the endometrium during surgery to the uterus or the abdominal area, such as a cesarean section (C-section) or hysterectomy.
- Retrograde menstruation: Cells from the endometrium that are shed into the uterus during a period are carried backward through the tubes and into the pelvis, where they can implant.
- Transport by circulation: Endometrial cells are carried from the uterus to other areas of the body via the lymphatic system and blood vessels.
- Embryonic cell growth: Cells within the abdomen and pelvis turn into endometrial cells.
- The immune system: Problems with the immune system may lead to failure in detecting and destroying endometrial tissue outside of the uterus.
- Induction of peritoneal cells: Hormones cause peritoneal cells, which line the inside of your abdomen, to transform into cells that resemble endometrial cells.
Endometriosis Risk Factors
Certain factors may place you at higher risk for developing endometriosis. The following are risk factors for endometriosis2:
- One or more relatives with endometriosis
- Abnormalities in the reproductive and menstrual tracts
- Short menstrual cycles, i.e., less than 27 days
- Heavy menstrual periods that last longer than seven days
- Never having given birth
- Starting your period at an early age
- Going through menopause at an older age
- Having a history of high estrogen production
- Low body mass index
- Medical conditions that prevent menstrual flow
- Infertility
- Ovarian Cancer
Endometriosis Complications
What happens when endometriosis is left untreated? When left untreated, endometriosis can have lasting negative health effects, including infertility in many cases. Other complications can include problems with the bowel and a higher risk of heart disease.
Infertility
Endometriosis can cause infertility, and this can happen at any stage of the disease due to chronic inflammation and scarring. Some studies suggest up to 50% of women with endometriosis experience infertility.3,4 Endometriosis-related infertility is typically caused by:
- Tubal scarring, which prevents transport of the egg down the tube to the uterus by blocking the tubes.
- Inflammation, which impairs fertilization between the egg and sperm, making transport through the tubes more difficult and decreasing the likelihood of implantation of the embryo into the uterine lining.
- Endometriomas, or large cysts of endometriosis on one or both ovaries, which can destroy ovarian tissue and decrease ovarian reserve (the number of eggs remaining in the ovaries) and egg quality.
Bowel Problems
Endometriosis can affect the bowel in two ways: it can develop on the outside of the organ (called superficial bowel endometriosis) or penetrate the bowel wall in more severe cases. If endometriosis spreads to the outside of the bowel, it may cause the bowel to become stuck to other organs in the pelvis, such as the uterus or ovaries, causing chronic pelvic pain. Adhesions on the bowel can also cause constipation and diarrhea, as well as pain with bowel movements. In severe cases, deep endometriosis can infiltrate the bowel wall, causing rectal bleeding.
Increased Risk of Heart Problems
Studies have shown an increased risk for high cholesterol and coronary heart disease among women with laparoscopically confirmed endometriosis.5 Due to chronic inflammation and high levels of cholesterol, women, especially young women, with endometriosis may be more likely to develop chest pain, have a heart attack or undergo heart surgery.
Ovarian Cysts and Adhesions
In its later stages, endometriosis can lead to the development of adhesions (bands of scar tissue that can cause organs to stick together) and ovarian cysts (usually benign growths on one or both ovaries). These typically occur when endometriosis spreads to or near the ovaries.
Ovarian Cancer and Other Chronic Diseases
Studies investigating the link between endometriosis and chronic diseases have been inconclusive, but some research6 suggests women with endometriosis may be at a higher risk for ovarian cancer, breast cancer, cutaneous melanoma, asthma and some cardiovascular diseases. This underscores the need for early treatment for endometriosis.
References:
- Burney R, Giudice L. Pathogenesis and pathophysiology of endometriosis. Fertil and Steril. 2012;98(3):511-519
- Peterson CM, Johnstone EB, Hammoud AO, et al. Risk factors associated with endometriosis: importance of study population for characterizing disease in the ENDO Study. Am J Obstet Gynecol. 2013;208(6):451.e1-451.e4511.
- ASRM. Endometriosis and infertility: a committee opinion. Fertil and Steril. 2012;98(3):591-598
- Bulletti C, Coccia ME, Battistoni S, Borini A. Endometriosis and infertility. J Assist Reprod Genet. 2010;27(8):441-447. doi:10.1007/s10815-010-9436-1
- Mu F, Rich-Edwards J, Rimm EB, Spiegelman D, Missmer SA. Endometriosis and Risk of Coronary Heart Disease. Circ Cardiovasc Qual Outcomes. 2016;9(3):257-264. doi:10.1161/CIRCOUTCOMES.115.002224
- Kvaskoff M, Mu F, Terry KL, et al. Endometriosis: a high-risk population for major chronic diseases? Hum Reprod Update. 2015;21(4):500-516. doi:10.1093/humupd/dmv013
