Preparation for a CT scan

 For most scans, you have a drink or an injection of contrast medium, or both. This is a dye that shows up body tissues more clearly on the scan. You have the injection through a small thin tube (cannula) into your arm. The cannula stays in place until after your scan. This is in case you have any problems such as an allergic reaction after having the injection.

CT scans of the tummy (abdomen)

If you are having a CT scan of your abdomen, you might need to:

  • drink a liquid contrast medium some time before the scan
  • drink more of the liquid contrast or water in the x-ray department
  • stop eating or drinking after midnight the night before the scan (this is for a CT scan of the inside of the large bowel, called CT colonography)

You usually have the contrast medium by injection and also as a drink. This helps to show up the gut (digestive system Open a glossary item) more clearly in the scan.

CT scans of the head

For some brain scans, you might have an injection of the contrast medium dye beforehand. This is to make the scan clearer.

CT scans of the chest

You might have an injection of the contrast medium during the scan. This is to help show up the tissues close to the area containing cancer. For example, if your doctor wants to know if the cancer is affecting your blood vessels. It may help to show whether cancer can be removed with surgery or not.

Pelvic CT scans

The pelvis is the lower cavity of the body in the area between the hip bones. It contains the pelvic organs, including the bladder, lower bowel and reproductive organs. If you are having a CT scan of the pelvis, you might need to:

  • stop eating or drinking for some time before the scan
  • have an injection of contrast medium

Occasionally, for a rectal scan, you need to have an enema of contrast medium. This shows up on the x-ray and makes the outline of the bowel show up more on the scan. It might make you constipated. Your first couple of bowel motions will be white, but there are no other side effects.

CT colonography

You might have a very detailed scan of the bowel called a CT colonography (or virtual colonoscopy). 

For this test you need an empty bowel. You'll have strong laxatives and follow a special diet about 2 days before the test. You might also have a special liquid to drink called gastrorgrafin. It's a type of dye but also acts like a laxative. Your doctor or nurse will tell you about this. 

You might also have a medicine to slow down the normal movement of your bowel. This movement (called peristalsis) can change the scan and make it more difficult to read.CLICK HERE

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