A CT virtual colonoscopy is a scan of the abdomen using Computed Tomography (CT) that produces 3-D images of the bowel. It is done to identify lesions in the bowel such as polyps, tumours or ulceration.
You will need to lie on a narrow table which moves in and out of the scanner during the procedure.
A small, plastic needle (cannula) will be inserted into a vein in your arm, and then IV contrast is injected to allow your organs to be seen more clearly You may also be given medication (Buscopan) to relax the muscle wall of your bowel. It is important to inform the staff if you are allergic to this medication or if you have neuromuscular diseases, prostate problems, a disorder of the gullet “oesophagus” (achalasia), or a fast heart rate (tachyarrhythmias).
Prior to the injection of contrast, your bowel will need to be inflated. You will lie on your side, where a nurse or doctor will insert a very small tube partially into your rectum. Once in position, then air is pumped through this tube in order to inflate the bowel. During inflation, you may experience some abdominal discomfort, similar to wind-like pain. Inform our staff immediately if the pain becomes extreme.
A scan will be done to see if enough of your bowel has been inflated and if more air needs to be given. You will then receive the injection of contrast, and one or two more scans will be done. During the scans, you will be required to keep still and hold your breath for a short period of time.
For one of the scans, you will be required to lie on your front.
Before your CT Virtual Colonoscopy Scan
The day before your CT Virtual Colonoscopy scan, you will be required to have a clear liquid diet and start taking the medication to prepare your bowel. You will be given three types of medication. “BARIUM”, GASTROGRAFFIN” and “GO-KIT”. These must be taken at the times indicated on the bowel preparation form, which will be provided. Follow the instructions on the form and in the kit starting the day before the test.
It is important to note: the procedure cannot be performed if you have had a biopsy of your bowel (colon) within the last 2 weeks. When you arrive for the scan, you will be asked to read and complete some forms.
Before the procedure, you may be asked to change into an examination gown for your comfort, and to ensure clothing does not affect the imaging. You may also be asked to remove jewellery, eye-glasses and any metal objects that might interfere with the imaging.
The CT Virtual Colonoscopy scan usually takes up to 60 minutes, including time waiting in the department after the procedure.
You may feel the urge to empty your bowel. It is likely you will pass a certain amount of air, and you will be taken to the bathroom immediately after the procedure.
Once you have dressed, you will be required to wait for 20 minutes before the plastic cannula is removed and any side effects from the buscopan, including blurred vision, has resolved.
Risks / Side Effects
Buscopan is a relatively safe drug used to relieve stomach cramps. Possible side effects of Buscopan include dry mouth, blurred vision, itchiness, drowsiness and increased pulse rate. If you experience any of these, they should pass quickly. Rarely, it can cause an inability to pass urine. In patients with untreated or unknown glaucoma, it may cause a red, swollen eye. If you experience pain in the eye or deteriorating vision, please go to an emergency department.
When the injection goes in you may have a warm feeling in the face, neck or pelvis. This usually lasts for a brief period then disappears. These feelings are normal and not an allergic reaction. Occasionally (<1%), mild allergic reactions such as a rash, hives or sneezing can occur. These usually develop at the time of scanning, do not require treatment and settle rapidly. Sometimes a mild reaction such as a skin rash may occur from 1 hour to 1 week after injection.
Read more information on IV contrast.
It is common to feel some abdominal discomfort and cramping from the air in the bowel. You may feel some nausea. Risks of inflating the bowel include:
- Bowel perforation
If severe, these may require surgical intervention.
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