If you have an abnormal FOB test, but aren’t able to have a colonoscopy, you may be offered a barium enema.

A barium enema is a special x-ray of the large bowel. It's important that the bowel is empty so that a clear picture can be seen. You will need to follow a special diet and will be given an instruction sheet by your hospital.

For the barium enema, a mixture of barium (which shows up on x-ray) and air is passed into the back passage using a small flexible tube. It’s important to keep the mixture in the bowel until all the x-rays have been taken. The doctor can then watch the passage of the barium through the bowel on an x-ray screen and look for any abnormal areas.

A barium enema takes about 30 minutes and can be uncomfortable and tiring, so it's a good idea to arrange for someone to travel home with you if possible.

For a couple of days after your enema, you may notice that your stools are white. This is the barium being removed from the body and is nothing to worry about. The barium can also cause constipation and you may need to take a mild laxative for a couple of days afterwards.