What causes endometriosis?

There is a misconception amongst doctors and patients that endometriosis is caused by retrograde menstruation, but that isn’t necessarily true, says Dr. Abhishek Mangeshikar, a Mumbai-based endometriosis excisional specialist with the Indian Centre for Endometriosis.

The Mumbai-based expert says that as many as 90% of women undergo retrograde menstruation, but not 90% of women have endometriosis. According to a theory propagated by American gynaecologist John Sampson in the early twentieth century — during menstruation, pieces of the endometrium or the lining of the uterus, flow into the abdominal cavity through the fallopian tubes, adhere to the peritoneal lining and develop into endometriotic lesions.

Endometriosis is a painful condition wherein tissue resembling the endometrium, or the lining of the womb, starts to grow in other places in the body. It usually occurs in the lower abdomen or pelvis, but it can appear anywhere in the body.

We spoke Dr. Mangeshikar about the causes of endometriosis, the presentation of pain, as well as the relationship between pain and the stage of disease. Edited excerpts:

• Tell us about the causes of endometriosis?
• How long does the pain last?
• The stage of endometriosis is not necessarily correlated with pain. Tell us more about that?

Tell us about the causes of endometriosis?

The cause of endometriosis is a difficult question to answer because nobody really knows. What’s taught in med school is not correct. It is taught that it is retrograde menstruation, or your period flowing backwards.

However, almost 90% of women undergo retrograde menstruation but not 90% of women have endometriosis. What is usually taught in medical school does not explain the different sites that endometriosis occurs in. You can find endometrial tissue on the diaphragm, on the lungs. So, how does it reach there? Endometrial tissue has even been demonstrated in the fingernails or in the gums. So, obviously retrograde menstruation does not account for all of those presentations, although they are rare.

There are a few workable theories. There is a multi-theory that there are different kinds of endometriosis, because they have such different presentations. An ovarian cyst or an endometriotic cyst will be very different from superficial peritoneal disease (endometriosis involving the peritoneum or the lining of the abdomen), or a deep fibrotic nodule of the rectum.

There are different theories of origin regarding endometriosis. One of the good ones is the theory of Mullerianosis (published by Dr. Ronald Batt, a pioneer in the field of endometriosis, and his colleagues in 2007). According to this theory, during embryo formation when the organ systems divide, there are stem cells that are laid down along the way. Under epigenetic change (epigenetic changes alter the physical structure of DNA) — like the onset of a period under the hormonal influence —  these will start undergoing change into endometriosis tissue. And that is why they are predominantly laid down into the pelvis in highest incidence, but you may find them higher up in the body in the small intestine or the appendix, on the liver, or on the diaphragm and above. These are the theories that I would think have a slightly higher evidentiary support.

In our previous conversation, you said that pain for endometriosis is predominantly in the abdomen. Tell us how long does the pain last?

Let’s say that zero out of 10 is when there is no pain, and 10 out of 10 is so bad that you can’t get out of bed. So most people will say that they’re an eight or nine, or a 10 for maybe one or two days. And then there is a kind of a downward sloping trend in pain. There are some patients, who have a constantly high pain score throughout, those are more acute cases. Patients with chronic pain, which is more than 15 days to a month, have acute pain for a few days, say an eight or a nine out of 10. The rest of the month, the pain intensity will be somewhere at five or six. These are some of the most typical presentations of pain.

You also mentioned that the stage of endometriosis is not necessarily correlated with how much pain you have. Tell us more about that?

The staging system that is most commonly used is the ASRM, the American Society of Reproductive Medicine staging.

These stages are designed towards fertility outcomes. The staging has no bearing on the difficulty of surgery, it has no bearing on the symptoms or the degree of pain that a patient will face. For example, If there is a deep nodule in the uterosacral (a fibrous fascial band on each side of the uterus that passes along the lateral wall of the pelvis), that patient is only stage two disease, while somebody with just a cyst and maybe a few rectal adhesions in the pouch of Douglas or the cul-de-sac is termed as stage four. Now, that stage four will take 45 minutes of surgery, while the deep nodule of stage two may take about two hours of surgery. 

The staging system that is most commonly used is the ASRM, the American Society of Reproductive Medicine staging. These stages are more designed towards fertility outcomes. The staging has no bearing on the difficulty of surgery, it has no bearing on the symptoms or the degree of pain that a patient will face.

The staging system is absolutely useless, in my opinion. There are other staging systems like the Enzian system, which is looking into identifying lateral disease and also factoring in adenomyosis, bladder disease and things like that. That is a step forward. But again, it’s not very easily adapted or adopted worldwide. And secondly, it’s a little difficult to understand. 

There is also the Endometriosis Fertility Index (EFI) classification, which is not really staging. It was more of a predictor of fertility outcomes. I think the staging for endometriosis needs a big overhaul. If you tell someone that they have stage four disease, you’re not really giving them any information. It can be anything. What I need to know as a surgeon will be a lot more information. In clinical practice, we don’t really rely on staging systems, although we may use it to explain to patients or for insurance purposes, but otherwise in clinical practice, when it comes to planning strategy for surgery, staging systems have no value to us.

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