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Further tests for bowel cancer

Men and women discussing bowel cancer

This page tells you about the tests you may have if you are diagnosed with bowel cancer. You can find the following information

 

A quick guide to what's on this page

Further tests for bowel cancer

If tests show that there is a cancer in your large bowel, you may need further tests to find out more about the cancer and whether it has spread.

CT scan

This type of scan takes a series of X-ray pictures of the body from different angles. The pictures are fed into a computer and form a detailed picture of the inside of your body.

MRI scan

This scan uses powerful magnets to build up a picture. An MRI scan can sometimes give more detail than CT scans for rectal cancers.

Ultrasound scan of the back passage

This is a type of ultrasound scan which is used to find out more about rectal cancer. The doctor or technician puts an ultrasound probe inside the rectum. This can be uncomfortable but the scan only takes a few minutes at most.

Other tests

Your doctor may also want you to have an ultrasound scan of the abdomen, a chest X-ray, blood tests or a PET scan. There is more information about the different types of scans and tests in the cancer tests section.

 

CR PDF Icon You can view and print the quick guides for all the pages in the diagnosing bowel cancer section.

 

Why you need further tests

If tests show that there is a cancer in the large bowel, you may need further tests to find out more about the cancer and whether it has spread. This is called staging. Doctors use this information to decide on the best treatment for you. You may have some of these tests again during and after your treatment, to see how well your treatment is working.

 

CT scan

A CT scan takes a series of X-ray pictures of the body from different angles. The X-ray images are fed into a computer and form a detailed picture of the inside of your body. If you have cancer of the large bowel, you are likely to have a CT scan of your chest, tummy (abdomen) and the area between your hip bones (the pelvis). The scan gives a detailed image of the cancer to show how big it is. Your doctor can also use the scan to check whether the cancer has spread to another part of the body, for example, to the liver.

Before the scan you may be asked

  • Not to eat or drink for four hours
  • To drink a special liquid a few hours before
  • To drink more of the liquid in the X-ray department

Just before the scan the doctor may put a liquid into your back passage (rectum). The liquid makes the scan picture clearer.

You may also have CT scans done as part of a virtual colonoscopy (CT colonography). There is more information about CT colonography in this section. There is detailed information about having a CT scan in the cancer tests section.

If you don't have a CT scan you may have a chest X-ray and ultrasound of your abdomen instead. If you have a rectal cancer you may also have an MRI scan of the pelvis and an ultrasound scan of the back passage.

 

MRI scan

An MRI scan uses powerful magnets to build up a picture of the body. It can sometimes give more detail than a CT scan and is commonly used for cancers in the back passage (rectum).

Your doctor may ask you to have this test with an endo anal coil. This is a small magnetic coil that goes inside your back passage during the scan. It is uncomfortable but gives a very clear picture of the rectum. You may want to ask your doctor beforehand how long you will need to have the coil in so that you know what to expect.

There is information about MRI scans in the cancer tests section.

 

Ultrasound scan of the back passage

This is a type of ultrasound scan doctors may use after rectal cancer has been diagnosed. It can help to show

  • The size of the tumour
  • Whether it has spread into the area around the rectum

To do the scan, you have the ultrasound probe put inside your rectum. This can be uncomfortable but the scan only takes a few minutes at most.

There is information about ultrasound scans in the cancer tests section.

 

Ultrasound scan of the stomach (abdomen)

This test uses sound waves to build up a picture of the inside of your body. You lie on your back and a nurse or technician spreads a gel onto your tummy (abdomen). They then pass a small microphone over your abdomen. The microphone picks up echoes and sends the signals to a computer, which converts them into a picture.

Your doctor may want to use this test to check your liver. The liver is one of the organs where bowel cancer can spread.

 

Chest X-ray

You may have a chest X-ray to check your general health and make sure there is no sign of cancer spread to your lungs.

 

CEA blood test

Some bowel cancers make a protein called CEA that can be found in the blood. CEA stands for carcinoembryonic antigen. Doctors usually take a blood sample to get a baseline reading of CEA levels when you are first diagnosed. Your doctor can then compare it to levels during your treatment to see if the treatment is working. 

Levels of CEA in the blood may also go up if the cancer comes back after treatment. But some bowel cancers do not produce any CEA, so your doctor may not order this test for you.

 

PET scan

Your doctor might suggest that you have a PET scan if they think that the cancer may have spread outside the bowel or into nearby lymph nodes. Doctors don't commonly use PET scans for bowel cancer but you may have one if the results of other tests are unclear. 

For a PET scan you have an injection into a vein of a mildly radioactive substance. Cells that are active take up the radioactivity and show up on the scan. Cancer cells are usually more active than normal cells. 

Your doctor may suggest a PET scan during or after bowel cancer treatment. They can sometimes show whether there are cancer cells still there or whether treatment is working and has killed them off. There is information about having a PET scan in the cancer tests section.

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Updated: 8 August 2013