After 16 rounds of surgery for endometriosis, Kate Fisher underwent a hysterectomy at age 34.
She thought it would mean an end to the debilitatingly painful periods – instead, she began shedding from her bowel each month.
Fisher is one of many women diagnosed with endometriosis who also experience gastrointestinal problems. She always had gut symptoms, including diarrhoea and reflux, alongside heavy painful periods, but assumed they were due to her endometriosis – until her uterus was removed.
Now, new research has found genetic links between endometriosis and gastrointestinal disorders, which may explain why symptoms overlap and sometimes lead to delay in diagnosis and treatment.
A study from the University of Queensland’s Institute for Molecular Bioscience published in the journal Cell Reports Medicine found endometriosis and irritable bowel syndrome (IBS), peptic ulcer disease (PUD), gastro-oesophageal reflux disease (GORD) and inflammatory bowel disease (IBD) share genetic risk factors.
Endometriosis is a chronic condition affecting at least one in nine Australian women, caused by tissue that resembles the uterus lining growing outside the uterus.
Doctors have for a long time observed that many women diagnosed with endometriosis also experience symptoms associated with gastrointestinal disorders including abdominal pain, bloating, constipation, heartburn, dyspepsia, vomiting, painful bowel movements, diarrhoea and nausea.
Prof Grant Montgomery, a co-lead author of the study, said the overlap in symptoms can lead to misdiagnosis and years of delay in treatment during which time the endometriosis can progress to more severe disease.
Observational data had shown the increased incidence of gastrointestinal disorders in women who have endometriosis, but the study is the first to examine genetic data and establish a causal relationship with shared genetic risk factors, Montgomery said.
The researchers analysed data from 188,461 unrelated women in the UK Biobank, a large-scale biomedical database containing genetic, lifestyle and health information from participants, and found a co-morbid relationship between endometriosis and each of the four gastrointestinal disorders.
The researchers then analysed the genetic data and found the causal relationship between gastrointestinal disorders and endometriosis went both ways.
The study found women with endometriosis are twice as likely to have an IBS diagnosis compared to women without the disease, and 1.4 times more likely to have a diagnosis of GORD.
They also compared medication use data for both gastrointestinal disorders and endometriosis from the Australian Pharmaceutical Benefits Scheme (PBS) with the Australian Longitudinal Study on Women’s Health (ALSWH) which provided further evidence of the likely co-occurrence of the diseases and disease symptoms.
The chair of the peak body for gynaecologists (Ranzcog)’s expert endometriosis working group, Prof Jason Abbott, from the University of New South Wales, said “for many diagnosed with endometriosis they will often describe being bounced between gynaecologists and gastroenterologists.
“With this new information, we now know that genetically, both are likely to co-occur, both need addressing and both have substantive impact on people’s lives,” Abbott said.
The study adds further evidence of the complexity and clustering of endometriosis with other painful conditions, he said. The largest ever study on the genetics of endometriosis published in March in Nature Genetics, found genetic links to 11 other pain conditions, including migraine, back and multisite chronic pain (MCP), as well as inflammatory conditions, including asthma and osteoarthritis.
“We need to do more to get to the bottom of what causes endometriosis and better ways to treat it,” Abbott said.
Prof David Amor, a clinical geneticist at the Murdoch Children’s Research Institute, said the researchers “present convincing evidence that IBS and endometriosis occur more commonly together than would be expected by chance alone – that is, there is an association between the two.”
Amor said the main strength was the use of very large population datasets. But he said the limitation – acknowledged by the authors – is that the clinical data used in the study could be incomplete, which is why findings are not definitive and need to be replicated in other studies. However, he said: “The genetic component of the study is robust.”
Fisher said she wanted to speak openly about her experiences so other women seek help for their symptoms.
“I don’t want other people to experience this and be really frightened and not understand what’s happening with their bodies. I want them to know that there is so many avenues of different ways that you can get help, and that you don’t have to live like this,” Fisher said.
