In the UK, an estimated 1 in 10 women and those assigned female at birth live with endometriosis. In endometriosis, tissue similar to the lining of the womb grows in other parts of the body, such as the ovaries, and lining of the pelvis. Symptoms include severe pain, fatigue, infertility and gastrointestinal issues.
Diagnosing endometriosis can be challenging as other conditions can cause the same symptoms. There is no simple test for endometriosis, though it can sometimes be spotted on scans. It is often only confirmed following a biopsy through a keyhole incision in the abdomen. According to the charity, Endometriosis UK, it takes an average of 8-9 years from the first GP visit to get a diagnosis. Research is aiming to develop new tests and speed up diagnosis.
The different types of endometriosis
There are 3 different subtypes of pelvic endometriosis, based on the region of the pelvis that the condition affects.
- Superficial peritoneal endometriosis: the disease is found in the superficial lining of the pelvis.
- Ovarian endometriosis: the disease is found within the ovaries.
- Deep endometriosis: the disease is embedded deep in the pelvis where it can affect the bladder, bowel, nerves and blood vessels. Deep endometriosis is the most severe form of the disease.
How can research help endometriosis diagnosis?
Understanding which endometriosis subtype a woman has is crucial for determining their risks from surgery. This may impact how they respond to medical treatments.
Improving diagnosis is one of the key challenges that endometriosis research is tackling. Teams around the world are looking for new biomarkers which might allow diagnosis of endometriosis with a blood or urine or saliva test. To find a biomarker, researchers need to analyse tissue samples from large cohorts of women from diverse backgrounds and with different subtypes.
One University of Edinburgh study, hoping to improve diagnosis and better understand the different subtypes, is ENDO1000. In the ENDO1000 study, 1,000 women with endometriosis complete a daily app to record their symptoms and treatments. They will also take biological samples that they can easily self-collect at home. These include blood, urine, saliva, vaginal swab and faeces. The researchers will analyse these to look for protein, genetic or hormonal markers for the disease.
Tissue samples from endometriosis patients can help in developing treatments as well. Three other studies, in Oxford, the West Midlands, and Hull, are also collecting samples from women with endometriosis. These will help to better understand the disease and its genetics, for both diagnosis and treatment.
What drugs work for endometriosis?
The first line treatment for endometriosis is painkillers. There is a need for new painkillers that are suitable for long-term use. One current trial in the UK is testing a new anti-inflammatory painkiller called vipoglanstat for use in endometriosis. Researchers are also trialling the use of cannabinoids for endometriosis. A new trial is looking at the effectiveness of cognitive behavioural therapy for managing pain in endometriosis.
Hormonal treatments, including the contraceptive pill, are also used for endometriosis. These can be effective for some women, but they aren’t suitable for everyone.
There is a need for new non-hormonal drug treatments. These could include immunotherapies, which harness the body's immune system to fight the condition. They could also be existing drugs for autoimmune or inflammatory conditions. One drug for endometriosis, now being evaluated in the EPiC2 Trial, has been used for 30 years to treat metabolic disorders in children.
Is surgery effective for endometriosis?
Surgery to remove endometriosis tissue is also offered to some women with the condition. The risks and outcomes of surgery depend on where the endometriosis is located. There is little long-term data on how successful surgery is. Most trials have only followed up for 6 months after surgery. A survey by Endometriosis UK found that many women see their pain return after surgery.
We still need more research evidence on the long-term outcomes from surgery. Another trial ESPriT 2, is following women for up to 5 years after surgery. 400 women in the trial had a surgical procedure under general anaesthetic that diagnosed endometriosis in the lining of the pelvis. Half of those women had the disease removed at the time of diagnosis. All agreed not to be told whether that had happened. The researchers want to see whether those who had their disease removed experience less pain than those who did not. They will compare the two groups at 12 months and then follow them for 5 years in total. 
The trial is led by Lucy Whitaker (pictured right) and Andrew Horne, both Consultant Gynaecologists and Academic Researchers at the University of Edinburgh. Dr Whitaker says: “Over 1,000 women agreed to take part in ESPriT 2, and I am hugely grateful to them. When women realised how little we know about the long-term impact of surgery, they were keen to take part. They wanted to help us answer that question, even though many were unlikely to benefit themselves. ESPriT 2 may show that surgery is effective or that it provides little benefit. Whatever the outcome, it will change the decision-making around surgery for both patients and clinicians.”
Women can be advised to take a contraceptive pill to reduce the chance of endometriosis recurring after surgery. The UK-wide REGAL trial is testing whether hormonal treatment can be more effective at preventing pain than repeat surgery.
There is now much more research underway on endometriosis. This will lead to better treatments, according to Dr Whitaker.
“Research is helping us to identify the subtypes, mutations and genetic variations in endometriosis,” she said. “Researchers previously looked at the same things in breast cancer patients. That has given us more effective and personalised treatments. I believe we’ll achieve the same with endometriosis."
"The women involved in research need to be as diverse as the disease itself. That's the only way we can answer all the questions we need to."
- Dr Lucy Whittaker
“We know it’s not always easy for women to get to a research centre. But there are studies, like ENDO1000, which women can be involved in from their own home. That makes the studies more accessible, and we hope, increases the variety of women who can take part.”
Join a study on endometriosis:
- FENOX: Fibroids and Endometriosis Study Oxford – A Study into the Biology of Uterine Fibroids and Endometriosis. (open until September 2030)
- Retinal Imaging for Systemic Inflammation in Endometriosis (open until August 2029)
- A Phase 2 Trial to Investigate Efficacy and Safety of Vipoglanstat in Women With Endometriosis (open until June 2027 – vipoglanstat is a new non-hormonal and non-opioid drug treatment)
- Predicting the Pain Outcome of Surgery for Endometriosis (open until August 2028)
- Exploring disease mechanisms of endometriosis (open until September 2027)
- Understanding and improving endometriosis experiences (HCPs) (open until February 2027)
- ENDO1000 - A UK-wide Endometriosis Research Project (open until December 2030)
- Identification of biomarkers and therapy targets for endometriosis (open until December 2032)
Use our study search tool to find a study that interests you.
How you can get involved with research
Sign up to Be Part of Research to be contacted about a range of health and care research. Or check out our full list of studies to see if one is right for you.
And if taking part in a study doesn’t feel right at the moment, there are other ways to get involved in research.
