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This patient information aims to answer some of the questions you may have about having a CT Pneumocolon. It explains what you need to do to prepare for the scan, what you can expect when you come to hospital and what happens after. If you have any further questions please speak to your consultant or the imaging department.
What is a CT Pneumocolon (also known as CT Virtual Colonoscopy)?
It is a procedure performed by a radiologist and can be used to investigate the large bowel. The radiographer assists in taking the CT images. CT is used as a diagnostic tool to assess your bowel. CT Pneumocolon includes a contrast media injection (Omnipaque 300) which helps assess all abdominal organs. However, CT Pneumocolon cannot take samples or biopsies of areas requiring further investigation.
What do I need to do to prepare?
A few days prior to your appointment you will receive a package from King Edward VII’s Imaging Department. This package will contain the preparation instructions and the drinking preparation required for the procedure. This will explain the types of foods that you can and cannot eat on the days leading up to the exam. You may be asked to swallow a fluid called a dye (contrast agent) around two days before the test. This fluid will help show your bowel more accurately on the scan. If you need an injection of contrast agent it may be necessary to stop certain medicines before the procedure. This may apply to people taking metformin, a medicine used to treat diabetes. If you are taking this medication, your doctor should give you instructions about what to do. You will be asked not to eat or drink for a few hours before your scan.
Asking for consent
The radiographer will ask you if you are happy for the scan to go ahead (verbal consent) and may only involve the radiographer checking that you are booked for the correct scan. If you do not wish to have the scan or are undecided, please tell the radiographer. It is your decision and you can change your mind at any time. Please remember to ask the radiographer any questions you have at any time.
What will happen during your appointment?
Once you arrive at the department we will ask you to change into a hospital gown. The procedure is performed in the CT scanning suite.
It involves inflating the large bowel and rectum with carbon dioxide or air. A very small, flexible tube will be passed a small way into your rectum to allow gas to be gently pumped into the colon. Sometimes an electronic pump is used to put gas into the colon. The gas helps to open (distend) the colon as much as possible which gets rid of any folds or wrinkles that might hide polyps or growths. Once the bowel is inflated two CT scans are performed, one lying on your back and one lying on your front. This procedure should not be painful but some discomfort may arise from the inflation.
To ease this discomfort a muscle relaxant known as Buscopan can be used if it is safe to do so. If you have any questions about Buscopan, please ask for our leaflet. The gas used in the procedure is then absorbed by your body and is naturally removed.
During the first scan it is sometimes required to enhance the scan with intravenous contrast. This contrast is used to highlight your organs and provide the radiologist with as much information as possible to get a better quality scan. To deliver this contrast it is required to put a cannula into a vein. The examination will take between 30-40mins in total, but the time varies from patient to patient.
Are there any side effects or complications?
The laxatives used to prepare your bowel can cause diarrhoea and may make you feel sick and bloated. Occasionally, some people sense a warm feeling or get a metallic taste in their mouth after having a contrast injection. This usually lasts only a minute or two.
If you have had muscle relaxants, these can temporarily blur your vision or make you feel dizzy.
Rarely, some people have an allergic reaction to the dye (contrast agent) which is sometimes used. This can be treated immediately. Very rarely, the dye may cause some kidney damage, most commonly in people who already have kidney problems. There is a very small chance that your colon may be damaged during the procedure. This can lead to bleeding and infection, which may need treatment with medicines or surgery.
How do I get my results?
The radiologist will write a detailed report having read your images. This report will be sent to your referring doctor. A CT scan has many images that make up the study, therefore it is very unlikely you will receive any results on the day.
If there is any chance of being pregnant, please notify the department. If you take oral contraceptives, continue to take them but use other precautions for the remainder of that cycle.
Please contact the Imaging team about any general concerns on 0207 467 4317. However, if you experience any symptoms of concern please contact your GP or go to your local Emergency Department (A&E).
Your comments and concerns
If you have any questions or concerns about your medicines, please speak to the staff caring for you. For support or advice please speak to your consultant or the Imaging department on 0207 467 4317.
Language and accessible support services
If you need an interpreter or information about your care in a different language or format, please get in touch.