Endometriosis is one of the most common gynecological disorders in the world. Any woman who has started her period can develop endometriosis, but it is more common among women in their 30s and 40s. The tissue lining the inside of the uterus (the endometrium) grows in the pelvic cavity, such as the fallopian tubes, ovaries, outside the uterus, or the bladder, ureters, bowel, and rectum. It may even grow in the cul-de-sac between the rectum and the uterus. Very rarely, the tissue grows outside the pelvic cavity – on the lungs, brain, spinal cord, knee, nose, and other body parts too!1
The severity of the pain caused due to endometriosis does not depend on the size or location of the lesions, implants, or nodules.
Patches of endometriosis are referred to as lesions, implants, or nodules. Implants can vary by size, color, and shape, but in the early stages, they are usually very small and appear like clear pimples. However, as they grow, they may develop into small nodules, flat lesions, or cysts called endometriomas. Cysts can be smaller than a pea or larger than a grapefruit and are colorless, red, or very dark brown. Cysts usually form on the ovaries and could be filled with old, thick, dark brown blood.2
Despite being a highly active area of medical research, no one knows for sure (yet) what causes endometriosis! Several plausible theories have been put forth, so let’s take a look at some of the most accepted ones.
1. Hormones Like Estrogen
It is clear that estrogen is the hormone that contributes to endometriosis. A long exposure to estrogen can result in endometriosis, as in cases of obesity, short menstrual cycles, and early-age menstruation. Receptors in endometrial cells bind to estrogen and another important hormone progesterone, both of which promote growth and thickening of the uterus. And when these cells attach to body parts and organs outside the uterus, and hormonal functions continue, it results in scarring and bleeding.3 4
2. Back Flow Of Menstrual Debris (Retrograde Menstruation)
One of the most widely accepted theories on why endometriosis occurs is that some of the uterine tissue that is shed during your period flows back into the pelvic area or abdominal cavity through the fallopian tubes instead of flowing out through the vagina. This phenomenon is commonly referred to as retrograde menstruation. However, retrograde menstruation does not fully explain endometriosis because nearly all women experience some level of retrograde menstruation but only a few get endometriosis.5
3. Immune System Issues
Disorders in the overall immune system may contribute to endometriosis.
- The immune system may not be able to detect and destroy endometrial tissue the way it should, and that allows the tissues to grow outside the uterus. This may explain why women with endometriosis also tend to suffer from autoimmune diseases such as Sjögren’s syndrome and rheumatoid arthritis and inflammatory bowel diseases like Crohn’s disease and ulcerative colitis.6 7 The connection, however, is still not clear and researchers are yet to decide if endometriosis should be treated as an autoimmune condition.
- On the other hand, the pain, infertility, and damage caused by endometriosis could be due to an overactive immune system. The body may perceive the endometrial implants to be hostile and attack them. Macrophages or large white blood cells are always high in women with endometriosis. Macrophages produce very powerful factors such as cytokines and prostaglandins, both of which cause inflammation and damage in cells and tissues.8
4. Genetic Reasons Or Birth Abnormality
There is a very strong possibility that endometriosis is genetically inherited since a family history of endometriosis makes you much more likely to have it.9 Studies are still exploring exactly how endometriosis may be passed on from mothers to daughters. Some researchers also believe that endometriosis is a birth abnormality where endometrial cells develop outside the uterus in a female fetus. Later in life, when this female child starts her period, these cells become painful lesions.10
5. Surgery In The Abdomen Or Pelvis
Surgical procedures can sometimes cause endometriosis. For instance, if a woman has had endometriosis undergoes surgery in the abdominal or pelvic area (including a C-section), she could have some endometriosis implants attach to the surgical incision. That could lead to endometriosis in the surgery scar later in life.11
6. Transformation Of Cells Outside The Uterus
Researchers believe that sometimes cells outside the uterus change and become like the cells that line the uterus. That is how endometriosis occurs in unexpected sites such as the thumb or the knee.12 But why this happens is yet beyond medical science’s undertsanding.
7. Movement Of Cells
Another reason attributed to endometriosis in other body organs such as the lungs is that the cells from the uterine lining travel through the lymphatic system or blood vessels and attach to these parts.13
8. Unexplained Causes
Endometriosis has been known to develop in women after hysterectomy (that is, removal of the uterus) too and, so far, no satisfactory explanation has been found for that. Another unexplained situation is the rare occurrence of endometriosis in men who have been exposed to estrogen during medical treatments.14
Endometriosis Risk Factors
As we have mentioned before, any woman who menstruates can develop endometriosis. You are, however, more likely to have this condition if:
- Family history: A family history of endometriosis makes you 6 times more likely to have it too.
- Early period: You started your period before the age of 11.
- Short monthly cycle: Your menstrual cycle is shorter than 27 days.
- Heavy period: Your period is particularly heavy and lasts more than a week.15
Can I Prevent Endometriosis?
Not really. There’s no sure-fire way of preventing endometriosis, but you can try to reduce your chances of developing it by lowering the amount of estrogen in your body. This is after all the hormone responsible for thickening your uterine lining each month. Some ways you can lower estrogen levels include:
- Using hormone-based birth control methods: Discuss birth control pills or patches that have lower estrogen levels with your OB/GYN.
- Avoiding excess alcohol: Limit intake to about 1 drink per day.
- Avoiding excess caffeine: Too much coffee, sodas, or even green tea can raise your estrogen levels. Stick to about one caffeine beverage a day.
- Exercising regularly: Get at least 4 hours of exercise a week to regulate your estrogen levels.16
About 3–10 percent of all women of reproductive age suffer from endometriosis worldwide. In the US alone, that translates to more than 5 million women!17 But since about 11 percent of women who have endometriosis don’t present any telltale symptoms, so the actual number of patients could be considerably higher. It’s important to know the causes and risk factors so that you can find out where you stand.
|↑1||Endometriosis. The American Congress of Obstetricians and Gynecologists.|
|↑2, ↑4, ↑8||Endometriosis. University of Maryland Medical Center.|
|↑3, ↑6, ↑15||Endometriosis: Condition Information. National Institutes of Health.|
|↑5, ↑11, ↑12, ↑13||Endometriosis. UCLA Health.|
|↑7||Endometriosis and co-morbidities. Endometriosis.org.|
|↑9, ↑16||Endometriosis. Office on Women’s Health.|
|↑10||Endometriosis. American Pregnancy Association.|
|↑14||Causes of endometriosis. Endometriosis UK.|
|↑17||How many people are affected by or at risk for endometriosis?. National Institutes of Health.|