The following tests are used to help determine whether a person has bowel cancer:
- digital rectal exam (DRE)
- faecal occult blood test (FOBT)
- colonoscopy
- virtual colonoscopy
- barium enema.
Digital rectal exam
A digital rectal exam is an examination of the rectum to check for any lumps or swelling. During the examination a doctor feels inside the rectum with a lubricated, gloved finger. The procedure may be uncomfortable but should not be painful. A digital rectal examination by itself is not used to diagnose cancer in the lower bowel.
Faecal occult blood test
A faecal occult blood test (FOBT) is a simple, non-invasive test that looks for blood in a bowel movement. An FOBT can be done at home and involves taking samples from two or three bowel movements using a test kit. The National Bowel Cancer Screening Program uses an immunochemical FOBT to screen for bowel cancer. If an FOBT finds blood, further tests are needed, the most common being a colonoscopy.
An FOBT involves using the small collection stick supplied with the FOBT kit to take a sample of your bowel movement. The stick is placed in one of the plastic tubes supplied with the kit, sealed and sent to a laboratory for testing.
People that test negative will be informed by return post. People who have a positive test will be referred to undergo a colonoscopy.
A positive FOBT does not necessarily mean that you have bowel cancer. Only about 5 per cent of people who have the follow-up colonoscopy will have a cancer and about 20 per cent will have a precancerous growth called an adenoma.
Colonoscopy
A colonoscopy is a test that enables your doctor to look at the inside of your bowel. If a polyp or bowel cancer is found, your doctor can remove it immediately during the procedure.
Colonoscopy is usually performed as a day procedure. Colonoscopies can also be used as a surveillance test for people at an increased risk of developing bowel cancer, for example if they have a strong family history of the disease.
Find out more about colonoscopy.
Virtual colonoscopy
A virtual colonoscopy uses a special type of X-ray, called a computerised tomography (CT) scan, to build a three dimensional picture of the bowel. It will show up any growths on the bowel wall. If growths are found, further tests will be needed to determine if the growths are cancer.
Barium enema
This is a special X-ray of the large bowel. Before the X-ray is taken, a white fluid containing barium (a metallic substance) is run into the bowel through the anus. The barium is later run out of the bowel and air is introduced.
Barium shows up under X-ray, so the X-ray pictures will outline the bowel and show any abnormal areas. If any suspicious or abnormal areas are seen, a colonoscopy is usually required.