How is IBD diagnosed?

Crohn's disease and ulcerative colitis share symptoms with other conditions. It may sometimes be necessary to exclude these other conditions before a definitive diagnosis can be reached. Getting an accurate diagnosis is essential to managing the condition

The first step towards reaching a diagnosis will usually involve a visit to your GP. Based on the history of your symptoms your GP will send a referral to a consultant gastroenterologist, who is a specialist in diagnosing and treating diseases of the gastrointestinal tract.

Physical Exam and Medical History

The investigation of Crohn’s disease and ulcerative colitis will initially involve the gastroenterologist taking a detailed medical history. The gastroenterologist will perform a physical examination to check for pain and tenderness in the abdomen, as well as the skin and other areas for signs of inflammation. They will then order some tests to help towards reaching a diagnosis. Your anus may also be examined for skin tags, fistulae, abscesses or bleeding.

Laboratory Tests

The gastroenterologist will order a series of blood tests. The blood tests are used to detect inflammatory activity, infection, intestinal bleeding, and deficiencies of substances such as iron, protein or minerals. Your doctor may also request a stool sample for analysis to check for blood or infection. The results of laboratory tests alone are not not usually sufficient to diagnose Crohn’s disease or ulcerative colitis, further tests and diagnostic procedures are required.

Physical Exam and Medical History

The investigation of Crohn’s disease and ulcerative colitis will initially involve the gastroenterologist taking a detailed medical history. The gastroenterologist will perform a physical examination to check for pain and tenderness in the abdomen, as well as the skin and other areas for signs of inflammation. They will then order some tests to help towards reaching a diagnosis. Your anus may also be examined for skin tags, fistulae, abscesses, or bleeding.

Laboratory Tests

The gastroenterologist will order a series of blood tests. The blood tests are used to detect inflammatory activity, infection, intestinal bleeding, and deficiencies of substances such as iron, protein or minerals. Your doctor may also request a stool sample for analysis to check for blood or infection. The results of laboratory tests alone are not not usually sufficient to diagnose Crohn’s disease or ulcerative colitis, further tests and diagnostic procedures are required.

Endoscopic Exams

Endoscopy is performed using an endoscope which is a flexible tube with a light and a camera which transfers images from your bowel to a television screen. Your doctor can also use this instrument to take biopsies (tissue samples) from your bowel wall. The following endoscopic exams may be used to aid diagnosis:

Colonoscopy and Sigmoidoscopy

Colonoscopy and Sigmoidoscopy allow your doctor to look directly into the large bowel via the anus using an endoscope.

Colonoscopy

An examination of the large bowel from the rectum to the caecum. Sometimes your endoscopist will be able to look at the lining of the terminal ileum, which is where the small bowel joins the large bowel. It is important that the bowel is empty for the test so that your doctor can get good views of the lining of the bowel wall. Your doctor will prescribe a special drink to take on the day before your examination to ensure this. You will be given sedation for the test, which takes approximately twenty minutes. You will be asked to rest in the recovery room for about an hour and you will be given light refreshments before you are discharged home.

Sigmoidoscopy

An examination of the left side of the bowel. You will be given an enema on arrival in the endoscopy suite to clean out the lower part of the bowel. You can choose whether to have sedation for this test. If you opt not to have sedation, you may experience some mild cramping or bloating during the test. You will be able to leave immediately after the test.

The doctor or nurse will give you preliminary results of the tests before you are discharged. If biopsies are taken, the results of these will be given at your next out-patient appointment.

Capsule Endoscopy

A recently developed technology which may be helpful in certain cases. 

Your doctor will likely diagnose inflammatory bowel disease only after ruling out other possible causes for your signs and symptoms, including ischemic colitis, infection, irritable bowel syndrome (IBS), diverticulitis and colon cancer. He or she will use a combination of tests. To help confirm a diagnosis of IBD, you may have one or more of the following tests and procedures:

Blood tests

Imaging Techniques

These are used to produce detailed images of the gastrointestinal tract and can be very effective in detecting inflammation. They are particularly useful for examining parts of the gastrointestinal tract which cannot be accessed by endoscope. These vary from patient to patient but may include some of the following:

Full Blood Count (FBC)

An FBC counts and measures the levels of the three main types of blood cells (red cells, white cells, and platelets). The number of white blood cells can indicate if there is any inflammation or infection in the body. An increase in the number of platelets (small cells involved in blood clotting) can also be a sign of inflammation. By measuring the level of haemoglobin (a molecule in red blood cells which carries oxygen through the body), an FBC test can detect anaemia – for more information see Ferritin and Transferrin Tests below.

Some of the drugs given for IBD, such as azathioprine and mercaptopurine, can affect the bone marrow and reduce the levels of red and white blood cells and platelets. People on these drugs are usually given regular FBC tests to help monitor their blood cell levels.

Inflammatory Marker Tests

Inflammation can increase the levels of some types of proteins found in the blood. Blood tests such as C-Reactive Protein (CRP) and Erythrocyte Sedimentation Rate (ESR) can be used to detect inflammation by measuring the levels of these proteins or ‘inflammatory markers’.

Liver Function Tests (LFTs)

A liver function test or LFT can help to show whether the liver is working properly. It can also be used to help diagnose some of the rare liver complications of IBD, such as Primary Sclerosing Cholangitis

Abdominal X-ray

This is an X-ray of your abdomen, which can be useful to check for inflammation and dilatation (widening) of your bowel.

Small Bowel Follow Through

A small bowel follow through is done to help the doctors assess your small bowel which annot be reached with endoscopy. You will have to fast before your test so that your stomach is empty. In the X-ray department you will be asked to drink a chalky liquid called barium. As it travels through your stomach and small bowel, several X-rays will be taken. Any areas that are inflamed will be noted as the barium is going through and will enable your doctor to accurately locate areas affected by disease.

CT Scan

Computed Tomography scans (or CT scans) are pictures taken by a specialised X-ray machine. The machine circles your body like a doughnut, and scans an area from every angle within that circle. It then relays that information to a computer, which generates a collection of black-and-white pictures, each showing a slightly different 'slice' or cross-section of your internal organs. This scan is more detailed than standard X-ray. You will have to fast prior to the scan and you may have to drink a special solution called contrast, which shows up on the scan and can help outline certain internal organs.

MRI

Magnetic Resonance Imaging (or MRI) is similar to CT but does not use X-rays. MRI uses magnets to send radio waves through the part of the body being examined, taking cross-sectional pictures. A computer puts the pictures together forming images of internal organs. In IBD, MRI is especially useful in looking for fistulae, both internal and external and at the small bowel. You may be asked to drink a special drink prio to the scan depending on what area of your gastrointestinal tract your doctor wants examined. The MRI scanner can be noisy, and looks like a tunnel.

In the case of acute attacks or repeated flares, your doctor may decide to repeat any of the above tests or examinations to re-evaluate your disease and to help decide on further treatment strategies.