Bowel disease is increasingly common

Doctors in Austria studied more than 1,500 people. They found those with IBD were up to three times more likely to suffer blood clots.

But writing in the journal Gut, they said further research is needed to find out why they were at increased risk.

Other studies have also suggested a link but they have not been consistent.

Increased risk

Professor Gottfried Novacek and colleagues from the University of Vienna surveyed 618 people with IBD, 243 with rheumatoid arthritis and 207 with coeliac disease. They also questioned 707 healthy people.

They found that 6.2% of IBD patients had developed a blood clot. This compares to 1.6% of healthy subjects, 2.1% of those with arthritis and 1% of those with coeliac disease.

Patients with IBD are at an increased risk of developing thromboembolism Researchers

"Patients with IBD are at an increased risk of developing thromboembolism, which seems to be a specific feature of IBD and was not observed in rheumatoid arthritis and coeliac disease," they said.

The researchers suggested that while there was no evidence to prove that IBD causes blood clots, it could not be ruled out.

They said many of those who suffered blood clots did so when their IBD symptoms were worst.

There are two main types of inflammatory bowel disease - Crohn's disease and ulcerative colitis.

Symptoms can range from abdominal pain to bleeding and weight loss.

Blood clots are potentially dangerous because they can travel to the lungs or the brain, cutting off the blood supply.