We all know that as adults and children with IBD you need to have lots of tests when you’re having a flare, as well as when you’re feeling OK. Some of these tests are to tell how your IBD is behaving, some are to monitor drug levels, and some are to get a deeper insight into your disease course and the impact it’s having on your body.

Professor Andrew Day previously wrote about blood tests, and you can access the article here for a refresher: https://hail.to/crohns-colitis-nz/article/is5ZyM8. But what about the other tests you have? We thought a brief overview of stool tests and radiology scans may be helpful to add to Professor Day’s article.

Stool tests

Faecal calprotectin. This is one of the most common stool tests carried out on people with IBD and is a helpful and non-invasive way of measuring disease activity. Calprotectin is a protein that is released in the gut when it is inflamed. Measuring faecal calprotectin can be used to work out whether your bowel symptoms are related to your IBD, and measuring it repeatedly over time can help your medical team keep track of your IBD as well as monitor your response to treatment. The normal level of calprotectin is less than 50, which for most people with IBD represents being in remission. You may still experience bowel symptoms when your level is normal, which may indicate that they are related to other important health aspects such as stress, food, or bowel infections.

Microscopy, culture, and sensitivity (MC+S). While diarrhoea is a very common symptom for people with IBD, the cause may not always be disease activity. If your medical team suspect that your symptoms may be due a gastrointestinal infection then they will order a stool ‘Microscopy, culture, and sensitivity’ test. The name of the test indicates the stages that are done. First, your stool will be studied under the microscope to see if there are visible infectious organisms (bugs) present which could be bacterial, viral, fungal, or parasitic. The stool is then added to culture plates to see which bugs grow when left alone. If they find organisms in your stool the laboratory team can then work out what type of treatment will be most effective by testing ‘sensitivity’ to different antibiotics. Your medical team can then treat the infection effectively (if it is a bug that needs treatment – some get better by themselves). Don’t forget that there are many organisms in your stool that are ‘good’ and benefit our body, but a few can cause problems and need to be treated. In addition to MC+S testing for bugs, doctors will often do a polymerase chain reaction (PCR) test to screen for other common gut infections.

Helicobacter pylori stool antigen test. To add to the previous MC+S test, a bacteria called Helicobacter pylori may cause specific gut symptoms such as abdominal pain, bloating, and nausea, although many people can have this infection and not know it. Helicobacter pylori may be tested for using a stool antigen test if you have these symptoms when you are in remission. If you test positive it can be treated with a course of antibiotics. The testing and treatment processes are different for children, and it is best to discuss this with their gastroenterologist if you have concerns.

Radiology

Ultrasound. An ultrasound is a scan that uses high-frequency sound waves to view live images from inside your body. It involves no radiation, so is safe for everyone. The scan is done while you lie on a bed, and a hand-held tool that looks like a small, flat microphone is pressed lightly to your skin and moved across your body over a warm gel. Ultrasound scans are a valuable tool for medical teams as they are pain free and non-invasive and can provide vital information on your bowel and the surrounding area. Ultrasounds can measure changes in your small bowel, which can’t be done using an endoscopy. Signs of inflammation that can be found using ultrasound may include areas of bowel wall thickening, extra blood vessels being formed, and enlarged lymph nodes. Ultrasound can also be used to look for fistulas or abscesses, and check how well your bowel is moving content through it.

MRI scan (Magnetic resonance imaging) or MRE scan (Magnetic resonance enterography). MRI or MRE scans use magnetic fields to create detailed images of your body, with MRE used specifically for your bowel. MRI/MRE are harmless and radiation free and involve lying on a bed that is moved inside a large tube. MRI/MRE scans can worry some people due to the closeness of the tube roof, and the scans can be quite noisy and long, but the radiology teams are very experienced in helping people cope with these aspects. MRE scans involve you drinking fluid that helps to expand your bowel a little. It is also common to have a small amount of intra-venous contrast to light up the wall of the small bowel. These two steps help to give the best pictures. MRI/MRE can be used to find areas of Crohn’s in the small bowel, internal bleeding, irritation and swelling, to find abscesses and damage to your bowel wall, as well as gut blockages. Having an MRI/MRE at different times can help your medical team see how well your treatment is working.

CT scan (Computed tomography). CT scans are painless and non-invasive, and they use X-rays that move in a circle around the body. A computer then turns these into pictures like ‘slices’ (horizontal images) of your belly. CT scans do use radiation, and involve you lying on a bed that a large ring moves along to take the X-rays, with you lying in the middle. CT scans may also need you to drink fluid to help your bowel show up, or for you to have a small amount of intra-venous drug, but these will all be discussed with you. CT scans show a much higher level of information than usual X-rays, and can provide detailed images of muscles, fat, organs, bones, and blood vessels. They are particularly helpful to view changes in the bowel and surrounding tissues in fine detail and can be used to assess bowel wall thickening, narrowing of the bowel (strictures), fistulas and abscesses, among others.

DEXA (Dual-energy X-ray absorptiometry). DEXA scans are used to assess your bone strength and may be carried out if your medical team want to check if you are at risk of osteopaenia/osteoporosis (low bone density) as a result of your IBD or treatment. DEXA scans are a type of X-ray that can assess your bone health and risk of bone fractures and do involve low doses of radiation. The scans are painless and involve you lying on a bed while a small X-ray scanner moves over different areas of bone. You do not need to take anything orally or intravenously for the DEXA scan and it is over very quickly. If you are found to have low bone density your medical team can discuss treatment with you.

Having an understanding of what all these tests related to IBD involve, including why they are being done, and what they may show, can help reduce anxiety about new procedures. After all, ‘knowledge is power.’ If you have any questions or concerns about tests you’ve had or may have in future, please speak with your medical team.