Computed tomography colonography explained

It is sometimes called virtual colonoscopy. Unlike a conventional colonoscopy, it does not pass a camera through the whole colon, and it cannot remove a polyp or take a tissue sample during the scan.

A small tube is placed just inside the rectum so gas can gently expand the bowel. The CT scanner then takes images, commonly with you in more than one position. Computer processing creates views that allow a radiologist to examine the bowel wall and the area around the colon.

The examination uses X-rays. A tagging drink or another contrast preparation may help distinguish remaining stool from the bowel lining, and some patients receive an injected contrast agent. The imaging team chooses the protocol for the clinical question and your health history.

Follow the imaging unit’s bowel-preparation and food instructions exactly, because stool can hide or resemble an abnormality. Tell the team beforehand if you may be pregnant, have kidney problems, diabetes, allergies, an inflammatory bowel condition, a recent bowel procedure, or difficulty managing bowel preparation.

During inflation you may notice fullness, cramping, or an urge to pass wind. Tell the radiographer if discomfort becomes severe. After the scan, you can usually pass the gas. Follow any specific advice supplied for contrast material, medicines, eating, and drinking.

Mild temporary bloating can occur. Get urgent medical advice for severe or increasing abdominal pain, a swollen rigid abdomen, fainting, fever, persistent vomiting, heavy rectal bleeding, trouble breathing, or swelling of the face or throat. Follow the contact instructions from the imaging unit, or use emergency services for breathing difficulty or collapse.

Ask why CT colonography is suitable for you, which bowel preparation is planned, whether oral or injected contrast will be used, and how regular medicines should be handled. Clarify when results will be available and whether an abnormal finding could mean a separate colonoscopy for biopsy or removal.