Inflammatory bowel disease (IBD) refers to a group of disorders that cause prolonged inflammation of the digestive tract. The two most common forms of IBD are Crohn's Disease and Ulcerative Colitis (UC), and it is estimated that nearly 20,000 New Zealanders and over 75,000 Australians live with these conditions. Associate Professor Chris Hemmings, gastrointestinal pathologist at Canterbury Health Laboratories in New Zealand, explains that there are still many unknowns about IBD.

“The exact cause of IBD is not known, however it is thought to be the result of altered immunity. It’s probably a combination of environmental factors affecting a person with a genetic predisposition – IBD does tend to run in families but it’s not a straightforward inheritance pattern like we see with some other diseases. Environmental triggers can include infections, certain medications, and smoking. IBD is likely to be caused by a combination of these different factors.

“Some nonsteroidal anti-inflammatory drugs (NSAID) such as ibuprofen can cause an IBD-like illness, however, it is not known whether NSAIDs cause IBD or whether they just trigger disease in people who were going to get it anyway. Similarly, with infections such as Campylobacter (a type of food poisoning), it is debated whether the infection triggers the immune system and brings on IBD, or whether that person would have got it regardless,” said A/Prof Hemmings.

For some people, IBD is only a mild illness. For others, it's a debilitating condition that can lead to life-threatening complications. The most common symptoms of IBD are persistent diarrhoea, abdominal pain, rectal bleeding/bloody stools, weight loss and fatigue. Other parts of the body can also be affected in some people, including joints, skin, eyes and the liver.

“Most often, IBD is diagnosed histologically. If someone is showing symptoms, most often they would be sent for a colonoscopy and if the bowel looks inflamed, a biopsy would be taken and sent to us for examination. Occasionally, we also make the diagnosis from surgical specimens, where people have presented acutely and needed urgent surgery, for example because their bowel has perforated. There is also a blood test called calprotectin, which can be elevated in IBD, but in my experience it is not really very sensitive or specific. This test can be used as a screening test when someone has symptoms like diarrhoea, but diagnosis ultimately comes down to a colonoscopy and a biopsy.

“People with IBD will need to come in and have repeat biopsies for surveillance. This is because long standing inflammation in the bowel predisposes an individual to the development of cancer. We will monitor how much inflammation there is and if there are any pre-cancerous changes in the mucosa (the lining of the bowel). In Crohn’s disease, people may also develop fistulas (where the inflammation goes right through the wall of the bowel and the contents can leak into another organ such as the skin, the vagina or the bladder). This causes significant problems and will require surgery,” said A/Prof Hemmings.

There is currently no cure for IBD. The goal of treatment is therefore to reduce the symptoms, achieve and maintain remission, and prevent complications. There are many different medications to treat IBD. Some are used to control inflammation while others are used to control symptoms.

“We have seen big improvements with drug treatments in the last 10-20 years. When I was a trainee 20 years ago, we quite often had people having to have quite large parts of their bowel removed – we still see that from time to time, but it is a lot less common now thanks to better drugs.

“Current drugs modify the immune response, but they need to be carefully balanced and closely monitored. Too much and you could suppress the immune system, putting someone at risk of developing infection. In some cases, UC may be confined to the rectum and not the rest of the bowel, and in that case an enema-type steroid can be used to act locally on the lining of the rectum without having the systemic effects of taking a drug,” said A/Prof Hemmings.