How Can We Not Know What Causes Endometriosis?

Illustrated by Louisa Cannell
In December 2009, two years after I was sexually assaulted in a bathroom stall on a night out, I was hospitalised for acute abdominal pain associated with an alarming amount of bleeding and vomiting. Nearly a decade later, a sexual assault specialist would tell me that this timing is precisely what she would expect to see in the development of the chronic physiological symptoms of sexual trauma.
Then, in 2018, I was diagnosed with endometriosis – a disease which I have since learned from Dr Mathew Leonardi, a gynaecological surgeon at McMaster University, Canada and PhD candidate at the University of Sydney, Australia, can be "as severe as cancer". The process of getting to these diagnoses was disheartening and torturous and humiliating. I remember so clearly the day it all began: 17th November 2009. I sat in a Sydney emergency department coiled over myself in pain, wondering what on earth could have happened to me. I didn’t realise, then, how many more times I would have to do this before I would have any answers.
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Endometriosis is a disease where tissue similar to the lining of the womb starts to grow in other places. In women and people with female reproductive organs who have the condition, the tissue grows outside the uterus, in all sorts of unsuitable places. The tissue – called endometrial-like cells – can grow on various abdominal organs: the bladder, the bowel, the ovaries, the kidneys. It can even grow on the lungs and brain.
The abnormal cells spread and can grow so prolifically that they overrun these organs like a cancerous carpet. If it is particularly aggressive, the tissue can stop the organs from moving around in the body, trapping them and suffocating them until they can barely function. I wouldn’t learn this until after my first hospital admission, when a doctor told me after a transvaginal ultrasound that my endometriosis was so bad that it had brought my whole abdominal infrastructure to a standstill. This worked for my diagnosis but, generally, the only definitive way to diagnose endometriosis is by a laparoscopy.
The endometriosis, my surgeon explained, can cause a build-up of damaged tissues that form into masses known as fibrosis, like tumours which sit in the body and grow and metastasise. The body then starts to attack the damaged tissue, causing what some doctors believe is an inflammatory auto-immune response that can take over the body and cause systemic symptoms including joint aches and body pains, cognitive problems and confusion, headaches and chronic fatigue.
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My doctor showed me images of my organs from the surgery. It looked like an abandoned battleground: everything torn apart, shredded, bloody. Broken. He paused and let me process the images. He watched my face as it moved from shock to fear to relief. "You didn’t make this up," he said. "I’m not surprised you’ve been in so much pain."
The reason my endometriosis took so long to diagnose is because it is chronically misunderstood by doctors, research scientists and politicians. I am not alone in my struggle to have my condition recognised.
Endometriosis UK says that one in 10 British women and people with reproductive organs suffer from endometriosis but for each one of them it takes an average of seven and a half years for the disease to be diagnosed. These statistics are much, much worse for Black women in the UK, who are half as likely to be diagnosed with endometriosis as white women.
The fact that so many women and people with uteruses are left to suffer without diagnosis or treatment for so long is alarming to many endometriosis specialists. On top of this, when patients do get a successful diagnosis, the battle for relief continues almost unabated.
Because the condition is under-researched and misunderstood, treatment options are extremely limited and there is no known cure. As if that’s not enough, we still don’t know what causes endometriosis in the first place.
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Back in 2018, understanding that endometriosis may be one of the long-term effects of my sexual assault meant I was finally grasping one of the many possible causes of the elusive, debilitating disease that was ravaging my body. 
Arvind Vashisht, a consultant obstetrician and gynaecologist at University College London Hospital, told Refinery29 that endometriosis, just like many lifelong conditions, including cancers, is caused by a multitude of factors that 'switch on' a particular auto-immune response and cause damaged tissue to grow and spread. But we don’t know yet what causes that switch to turn on.
It could be connected to trauma and stress held in the body, as my own doctors have suggested and as is argued by doctors such as Michèle Albina Piérobon. In her 2014 study, Dr Piérobon found that 91% of patients with endometriosis had a history of one or more traumatic experiences. A recent study of 60,000 sufferers by Holly Harris, ScD, an ovarian cancer and endometriosis researcher at the Seattle-based Fred Hutchinson Cancer Research Center, showed a link between endometriosis and experiences of child abuse.
Another possible cause, Dr Vashisht tells me, is something called retrograde menstruation, which is when menstrual blood travels the wrong way through the body and ends up in the pelvis.
What doctors have discovered more recently thickens the plot even further. It’s possible that many women have retrograde menstruation without developing endometriosis. The thing that causes the disease itself is the immune system’s response to the foreign tissue – something going awry in the auto-immune system which causes the body to attack the cells as if they are external toxins, rather than part of the body.
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This line of thinking is driving a growing body of evidence that endometriosis could be, more than anything else, a disease of the immune system.
When we spoke, Dr Vashisht confirmed a fear I have been harbouring for much of 2020. If endometriosis is an as yet unconfirmed auto-immune disorder, does this mean its sufferers are immune-compromised and therefore at a higher risk of severe COVID-19 complications?
It strikes me that living through a global pandemic highlights the injustice of how little we know about endometriosis – one in 10 British women could be high-risk COVID patients and not even know it. That is to say nothing of the patients who have endometriosis but are not yet diagnosed.
"The theory about those patients who are at higher risk of COVID-19 complications is that they have an auto-immune problem that leads them to mount an overactive immune response to the virus," Dr Vashisht said.
"So there is definitely a potential parallel there with endometriosis patients," he added.
I spoke to another endometriosis specialist about this – Dr Peter Barton-Smith, the founder of the Endometriosis Clinic at the Princess Grace Hospital – who said that it seems more likely than not that the key to understanding endometriosis is not the presence of the damaged tissue itself but the immune system’s overactive response to it. 
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"We are noticing that a huge number of endometriosis sufferers also have an auto-immune disease, such as lupus, indicating that endometriosis may well be related to a problem with the immune system," he told me. 
This is certainly true for me. Not long after I was diagnosed with endometriosis, I was also diagnosed with Crohn’s disease, a condition which causes inflammation throughout the body as a result of the body attacking itself.
Even if we knew what caused endometriosis or how to effectively diagnose it, we cannot treat or cure it. The only treatment available to properly relieve a patient of endometriosis is to surgically remove all fibrosis and tumours through one of two kinds of invasive surgery: excision surgery involves cutting the damaged cells out from their root, while laparoscopic ablation of endometriosis involves burning away the tumours and scar tissue superficially. I think I have undergone both of these although I must admit that I don’t know for sure because I didn’t learn that there were two different versions of the surgery until this year.
Surgical treatments aside, the only treatment options for managing the disease are hormonal approaches, often through the contraceptive pill, and generic pain management.
How on earth is it possible that a disease which causes lifelong disability for so many women and people with female reproductive organs is so under-researched and poorly treated?
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I asked Dr Mathew Leonardi. He reiterated that he believes endometriosis should be treated as seriously as ovarian cancer – with the same amount of research funding, clinical trials and focus on patient wellbeing.
"There are many similarities between endometriosis and cancer," Dr Leonardi told me.
"These include the way the disease grows and spreads around the body and the extremely debilitating impacts it has on a patient’s quality of life."
Dr Leonardi said that endometriosis deserves the same 'respect' as cancer but instead the majority of patients are left with poor treatment and disabling symptoms.
When I asked him why, he said there are a number of reasons but a big one is that the condition is not immediately life-threatening.
"While endometriosis is not a disease that typically kills a patient," he said, "it can certainly kill huge parts of a patient’s life. The medical profession isn’t accounting for that."
He also told me that classifying endometriosis as seriously as cancer would allow for much better surgical outcomes as well. The surgeries required to remove endometriosis – of which I’ve had seven – are incredibly complex and very similar to the process of removing cancerous cells, Dr Leonardi said.
In order to qualify to remove ovarian cancers, doctors must undergo many years of additional training. This is not the case for endometriosis specialists, Dr Leonardi told me. Therefore patients can opt for the surgical route and still not have all their damaged tissue removed or all their symptoms resolved as the surgery is extremely technically difficult and under-trained surgeons risk overlooking disease and failing to excise it.
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Dr Barton-Smith said he regularly sees patients who have been told after diagnostic surgeries that they definitely do not have endometriosis. Yet when Dr Barton-Smith reviews their surgical images, he can see nodules of disease which less specialised doctors have missed. This leads, he said, to an alarming number of false negative diagnoses.
I am extremely lucky to have had a relatively early endometriosis diagnosis due to my being white, middle class, cisgender and with access to universal healthcare. But I still feel ashamed of my pain after so many years of having it dismissed and delegitimised by doctors who didn’t believe what I was telling them. I have internalised this shame – there are days when even I don’t believe that my extreme pain and disabling symptoms are real.
There’s only one way to stop this from happening and that’s to make sure that we get clearer answers about the causes of and treatments for endometriosis so that people like me – and particularly those towards whom the healthcare system is much more prejudiced than it was towards me – don’t have to languish in pain and uncertainty for so long that it becomes a part of them, a part that is much harder than damaged tissue to excise.
Editor's note: This article was amended on Friday 11th September at 14.26pm to include additional treatment options for endometriosis and to clarify that the damaged tissue associated with endometriosis causes fibrosis.

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