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Until recently, doctors treated all cases of endometriosis with the same approach, usually involving surgery. Illustration: Hannah Izzard/Guardian Design

A common treatment for endometriosis could actually be making things worse

This article is more than 2 years old
Until recently, doctors treated all cases of endometriosis with the same approach, usually involving surgery. Illustration: Hannah Izzard/Guardian Design

Repeat surgeries for endometriosis could be exacerbating pain symptoms, experts say

It has long been believed that the best way to treat endometriosis, a chronic inflammatory condition that affects one in 10 women globally, is by performing laparoscopic surgery to remove damaged tissue from the body.

But experts now say the surgery may not be as effective as once thought in relieving symptoms, and could actually be making things worse for some patients, including those who have developed separate pain conditions as a result of their endometriosis.

“We find that patients don’t always get better with surgery, and those who do often feel better for a very short time,” Andrew Horne, a professor of gynaecology and reproductive sciences at Edinburgh University’s MRC Centre for Reproductive Health, tells the Guardian.

Patients with cystic ovarian endometriosis are likely to experience significant relief from having surgery to remove the cysts. Photograph: Morsa Images/Getty Images

Broadly speaking, endometriosis is a disease where tissue that is similar to that which is normally found inside the uterine walls – called endometrial tissue – is found growing in other parts of the body. It was once considered a pelvis-only disease but it has now been found growing on every organ of the body.

Horne says endometriosis should in fact be clearly delineated into three separate strands of disease: superficial peritoneal endometriosis, cystic ovarian endometriosis (or endometrioma) and deep endometriosis.

Until recently, Horne says, doctors treated all cases of endometriosis with the same approach, usually involving surgery. But evidence now shows that the best treatment depends greatly on which of the three kinds of disease a patient has, and the type of endometrial-like tissue that is found.

The ovarian strand of the disease involves clumps of the errant tissue growing in the ovaries, which commonly forms cysts that can burst and cause severe pain and inflammation. Patients with this strand are likely to experience significant relief from the removal of these cysts, says Horne, so surgery is often a necessary part of the treatment process.

But 80% of endometriosis sufferers have superficial peritoneal disease and, in these patients, it is less likely that the errant tissue itself is causing the majority of a patient’s pain and symptoms. Instead, the way that the diseased tissue interacts with nerves in the pelvis is usually the main culprit.

In these cases, surgery could actually be making things worse.

what is endometriosis interactive diagram

The nerve connection

Pain is by far the most commonly reported and most severe symptom of endometriosis. A 2021 study found that 59% of women with endometriosis report having experienced pelvic pain for more than five years. A 2020 study found that 39.9% of patients have experienced pain so severe they needed to present to an emergency department.

But like the disease itself, these sensations are all referred to under the umbrella of “pelvic pain”, despite important differences.

“There are many different mechanisms that can cause pain in endometriosis, and the different types of pain will respond to different types of treatment,” says Katy Vincent, a senior pain fellow and associate professor in Oxford University’s Nuffield Department of Women’s & Reproductive Health.

“Surgery is a very important tool in treating endometriosis – but we need to better understand when and how it should be used as part of a more personalised treatment plan.”

The kind of pain we most commonly think of – the pain associated with an injury such as a broken arm or a scalding burn – is called nociceptive pain. In the case of endometriosis, there will usually be some degree of this kind of pain, based on the presence of the diseased tissue.

But it’s not always the primary suspect, Vincent says.

Research increasingly shows that a lot of endometriosis sufferers experience high degrees of neuropathic pain, or pain that emanates from damaged nerve endings.

The Oxford team believe there are likely to be three ways in which nerve pain can develop in endometriosis patients. The first is that the nerves surrounding the disease lesions become hypersensitive. The second is that some lesions compress the nerves physically and thus cause pain. And the third is that nerves can be damaged during endometriosis-associated surgery.

Nerves and blood cells can actually grow inside endometrial lesions, according to Dr Christian Becker, associate professor at the Nuffield Department of Women’s & Reproductive Health. That means that when surgeons open up the pelvis to remove the diseased tissue, they often have to slice through some of the nerves that are bound up with the lesions or those that are close by. This severing of nerves can compound the neuropathic component and create more nerve pain.

Analgesics, nonsteroidal painkillers, hormone treatments and GnRH injections can all be used to treat endometriosis. Photograph: milos-kreckovic/Getty Images

“Patients whose symptoms are caused primarily by neuropathic pain are less likely to benefit from surgery, and could even experience more pain following surgery,” Vincent says.

Horne agrees: “In neuropathic pain cases, repeated surgeries are very unlikely to be a good thing. And in these cases, we need to figure out whether surgery is helpful at all.”

There are several licensed treatments for nerve pain, often used successfully in patients who suffer from neuropathic pain. Vincent says these drugs could be a far better course of treatment for those with severe nerve pain than surgery. But none of the drugs have yet been approved for use in endometriosis because the requisite research has not been conducted.

The vicious pain cycle

Another type of pain that endometriosis patients may be experiencing has to do with the central nervous system, says Lydia Coxon, another member of the Nuffield Department of Women’s & Reproductive Health. This occurs after the brain experiences pain without relief for an extended period, then adapts itself to send severe pain signals even if the tissue damage is not severe. The Oxford team describe this as central pain sensitisation, or “turning the volume up on pain”.

All pain experiences are produced by the brain, but with endometriosis, the central nervous system will sometimes send more pain signals to the brain than usual, particularly if a patient has previously overridden pain warning signs.

Vincent and Coxon made clear that this does not mean the condition is “all in a person’s head” or a consequence of depression or anxiety. That trope, which many endometriosis sufferers have heard, get the causative link the wrong way around.

“It’s never that a patient’s underlying anxiety causes or explains endometriosis,” Vincent says. “It’s that a patient who suffers from chronic, unexplained and untreated pain will often develop an anxiety or depression condition as a result of that pain.

“An anxious or depressed brain becomes more sensitive to the experience of pain, meaning that the psychological condition that a patient develops from living with the illness actually make the pain worse.”

Being in pain changes you, Becker says, and the anxious brain is then more likely to feel pain more acutely, and so the cycle continues.

All pain travels on a journey from the damaged tissue through the nervous system and spine to the brain before it is felt or interpreted by us. In endometriosis patients, doctors have found that things can go wrong at any stage of that process to amplify the pain, so it is important to understand which system is causing the majority of the patient’s pain.

What is chronic pain and how does it work? – video explainer

Because surgery doesn’t work on some patients due to the different types of disease and mechanisms of pain, doctors often order repeat laparoscopic surgeries in an attempt to cut out more and more endometriosis.

Not only will repeat surgery not work the second, third or seventh time if the patient’s pain is neuropathic or chronic, Horne says, but repeated surgeries also further exacerbate nerve pain and make the body more sensitive.

A revolution needed in diagnostics

Researchers have known about the three subtypes of endometriosis for the last decade but the distinction has only become widely accepted and well-researched in the past five years.

The only way to determine which subtype a patient has is through laparoscopic surgery, Horne says. That’s because while ovarian disease can show up on imaging tests such as ultrasounds, it is much less likely for either deep disease or superficial disease to appear on these screening tests.

Analysis of diagnostic laparoscopies tells us that about 80% of patients suffer from superficial endometriosis. For those patients, a nonsurgical screening process would be a much better first step to determine which treatments to use.

Horne says endometriosis experts are working on improving imaging tools such as ultrasounds and magnetic resonance imaging, or MRIs, in the hopes that in the coming years these screening tools will become more sensitive to superficial and deep endometriosis.

Endometriosis experts hope MRI scans can in the future become more sensitive to picking up superficial and deep endometriosis. Photograph: dowell/Getty Images

“We need to find ways to predict which patients are likely to respond to surgery and which patients will likely not respond to surgery at all,” Horne says.

A targeted approach to screening would also allow for a more patient-specific treatment plan. That could include surgery in cases where it is likely to improve symptoms, or otherwise a combination of the other available treatments for the disease. These include analgesics, nonsteroidal painkillers such as ibuprofen, hormone treatments such as the combined contraceptive pill and GnRH injections, which chemically induce a temporary menopause in the sufferer.

Unfortunately, endometriosis research remains chronically underfunded, and so we don’t yet have the diagnostic tools to make these distinctions, the experts say.

“Endometriosis continues to be more hidden than other diseases, partly because it is a women’s condition, and the funding and the research just isn’t there yet,” Vincent says.

Horne compares the situation to breast cancer: in the 20th century, the disease was under-researched and all patients were treated with the same blanket approach of chemotherapy and radiotherapy drugs.

But a huge public health push in awareness and funding led to a much better understanding of the condition, and now women are thoroughly screened at the time of diagnosis to determine which of a large arsenal of treatments will work best on their cancer.

Horne say the same needs to happen for endometriosis if we are to properly treat the disease and ensure we are not encouraging patients to undergo repeat surgeries that could be making their pain worse.

Sufferers of chronic pain have long been told it’s all in their head. We now know that’s not true. The pain that can’t be seen looks at why doctors are playing catch-up on chronic pain conditions like endometriosis, migraine and more – and what they have to do with long Covid.

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