The intestine is part of our digestive system, helping us digest the food we eat. There are two parts of the intestine:

After food is swallowed, it moves down the throat, or esophagus, and enters the stomach, where digestion will begin. Once it leaves the stomach, food progresses on to the small intestine and is broken down further. This is where the vitamins, minerals, and nutrients in our food are absorbed.

From here, food moves on to the large intestine. The large intestine is made up of the colon, the rectum, and the anus. Digested food first goes through the colon, where water is absorbed by the body. The remaining food then passes on to the rectum, where it is stored until it is ready to exit the body through the anus. The anus has a muscular ring that helps us control when we open and close the anus.


Colorectal cancer screening may detect colon cancer before it causes symptoms. If the cancer is spotted while it is in this first stage, it is more likely to respond to treatment.

Screening may also detect polyps. Polyps are benign growths and are therefore not cancerous. However, they may eventually become cancerous. Polyps are easily removed, thus reducing the risk of developing colorectal cancer.

The first step to screen for colorectal cancer is to perform a fecal occult blood test (FOBT). This test searches for tiny amounts of blood in patients' stool.

Results may be normal, abnormal, or inconclusive.

The results of this test will come back normal for around 98% of all people. If a patient's result is normal, they will be offered another test in two years' time.

Around 2% of people have abnormal test results. An abnormal result is not the same as a cancer diagnosis. It may be caused by other conditions such as hemorrhoids, a polyp, or an inflammatory bowel disease. Patients are generally advised to have a colonoscopy performed to examine their intestine. This test is performed so that your doctor can see what is behind your abnormal test results.

Nearly 4% of all patients may receive inconclusive test results at the beginning. If this is your case, you do not necessarily have colorectal cancer. It only means you have to have a repeat exam. Another test may be necessarily if there has been a technical problem in the laboratory when performing your test or if the test kit has been damaged for whatever reason.


Colonoscopy is a way of examining the lining of the intestine from the inside in search of abnormalities. It is the most effective method of diagnosing colorectal cancer.

Because patients must take the test on a completely empty stomach, you will be asked to follow a strict diet in the days prior to the test. You will also have to take a laxative. The department where you undergo the procedure will provide you with information on this.

You may be given a sedative before the procedure in order to help you relax. A small flexible tube called a colonoscope is gently inserted into the patient through the anus. Photographs and cell samples may also be taken from the interior of the large intestine to be examined. Most colonoscopies go off without a hitch, although there may be complications.

It may take up to three weeks for your colonoscopy test results to come back.


This test uses CT imaging to obtain a series of X-ray images of your intestine. Afterward, a computer puts all these images together to create a 3-D image of your intestine. This procedure may be performed in place of a colonoscopy or if a prior colonoscopy has failed to produce sufficiently clear images.

Your intestine must be completely empty for the test to be performed. You will have to follow a special diet for a few days before the test and also take a laxative before the procedure begins. Your hospital will give you instructions on what to do.

Your doctor may give you an injection containing medication that is meant to help your intestine muscles relax. In some cases, patients also receive an injection containing a contrast agent at this time. If this is necessary, your doctor will tell you.

Immediately before the CT scan begins, your doctor will insert a tube and an air and gas pump into your anus. This makes the intestine expand, producing a clearer image. Two CT images will be obtained—one while you are lying on your back and another while lying face down.


If any abnormal results are found in your FOBT and you are unable to undergo a colonoscopy, you may be encouraged to have a barium enema instead, although these procedures are rarely necessary.

A barium enema is a special x-ray of the large intestine. In order for your doctor to see your intestine properly, it must be empty when the procedure is being performed. You will have to follow a special diet before the test. Your hospital will give you the information you need to do this.

During the procedure, a mixture of barium and air is injected through a small flexible tube. Because the barium shows up on the X-ray images, the mixture must remain in the intestine until the procedure is over. Once the images have been taken, your doctor will be able to see how the barium passes through the intestine and whether there are any irregularities.

A barium enema takes about 30 minutes. It can be an uncomfortable and exhausting experience, so it is advisable for someone to accompany you during your trip home after the procedure.

You may notice that you produce white stool for a couple of days after the test. This is the barium being eliminated from your body, and it is nothing to worry about. Barium may cause constipation, so you may need to take a weak laxative for a few days after the enema.


  • As of what age can I have a colorectal cancer screening done?
    If you are worried about having colon cancer because of your family history, talk to your GP. Your GP can refer you to a specialist for screening and follow-up.
  • Is colorectal cancer screening mandatory?
    You are under no obligation to participate in the program and can decline the invitation if you so desire.
  • Will my diet affect the results obtained?
    Evidence suggests that certain foods such as red meat and some kinds of vegetables may make it more likely for blood to be found in your stool and therefore lead to a false-positive test result. However, it has not been clearly proven that your diet can affect the results of the test, and you will not have to alter your diet before picking up your test results.