CT colonography examination Patient information leaflet (361kB pdf)
Introduction
We hope this guide will answer your questions about your CT colonography examination. Please contact the team if you require further information via the details at the end of this leaflet.
What is a CT colonography examination?
A CT colonography examination is a specialised CT scan used to take a look at your large bowel (colon and rectum) using a CT scanner (x-rays).
Why do I need a CT colonography examination?
Your consultant has referred you for a CT colonography examination. This examination is performed in addition to, or instead of a colonoscopy procedure. The purpose of the test is to try and find out what may be causing your symptoms.
Who will carry out the examination?
Members of our radiology team, including radiographers, radiologists and nurses, are responsible for and will carry out your test. Our aim is to ensure that the examination is as safe and comfortable for you as possible. Our radiographers will perform your scan, the Radiologist will carefully look at the images afterwards and write a report for the team involved in your care. They can also answer any questions that you may have regarding the procedure.
Is the examination uncomfortable?
You may experience slight discomfort, but it should not be painful. Occasionally, people feel a cramp-like pain, which can continue for a short period of time afterwards.
How long will the examination take?
Although taking the images will only take a few minutes, the process of the scan will take a little longer to prepare. Therefore, you can expect to be in the radiology department for around 45 minutes to one hour.
What are the associated risks?
X-Ray radiation: All x-ray procedures involve exposure to radiation in varying amounts. The amount of radiation used in this test is equal to the natural radiation we receive from
the atmosphere over a period of approximately 3 years. The amount of radiation dose associated with a CT is greater than a plain X-ray because CT scans provide a more detailed 3D picture of what is going on inside the body. This detailed imaging can significantly aid your diagnosis or treatment. The dose you get from a medical x-ray is very low and your doctor along with the radiologists (x-ray specialists) have determined that the benefits of having the examination outweigh potential risks.
Due to ionising radiation regulations, only patients are allowed in the X-ray room.
Procedure risks: A CT scan is considered a very safe procedure.
Contrast injection: During your injection you may feel a slight warm to hot sensation, and may have a sensation of urinating, this does not happen but can feel quite strange. Occasionally some patients may feel nauseous during the injection, this feeling should
pass very quickly.
Extravasation: Extravasation is where during the injection of contrast, some of the contrast leaks into the soft tissue instead of going into the vein. This can cause a painful swelling in your arm or hand. If this happens we will apply an ice pack to aid with swelling and bruising and give you aftercare information. We may need to insert another cannula to continue your scan if this happens. Although rare, extravasations can happen. Our staff are fully trained to deal with these complications if they arise.
Allergic reaction: A very small number of patients have an allergic reaction to the x-ray
dye. This can be minor, severe, or even life threatening but the chances of this occurring
are very rare. If you get an itchy rash or difficulty breathing during the procedure tell a member of staff, the team will provide appropriate treatment. Before your examination begins the radiographer will ask you a series of questions about your medical history, including any allergies you may have. This will help us assess if you are at risk of an allergic reaction to the x-ray dye.
Bowel Perforation: There is a very small risk (approx. 1 in 3000) that the examination may cause a small hole in your bowel (a perforation). When it happens, most cases resolve without treatment but this, very rarely, may require hospital admission and observation under the care of a surgeon.
The bowel relaxant (Buscopan): can make your mouth dry and your vision slightly blurred which normally lasts for 15 to 20 minutes. Very rarely patients may develop pain or redness of the eyes which can occur in the 24 hours after the test. If this happens you should go to Accident and Emergency department immediately for a check-up.
Patients aged 12 to 55, could you be pregnant? X-rays can be harmful to an unborn
baby and should be avoided by patients who are or may be pregnant. It is recommended that the examination is performed within 10 days of the first day of your menstrual period. If your appointment is not within this time or if you think you may be pregnant, please contact the X-ray department before your appointment. When you arrive for your CT scan, you will be asked when your last period started. If it is more than 10 days earlier, your appointment may be postponed.
Breastfeeding: On the day of your CT examination, you will be given an injection of
contrast medium (Visipaque or Omnipaque). These agents are low risk contrast agents. A
very small percentage of the injected contrast enters the breast milk but virtually none is
absorbed across the gut of the infant. No special precautions are required and you can carry on breastfeeding as normal. However, if you have any concerns you may want to express some breast milk prior to your appointment. This information is from guidance provided by The Royal College of Radiologists.
Preparing for your examination
You will receive a letter asking you to call the radiology team to make an appointment for your examination. You will then receive a confirmation of your appointment via a telephone call or by letter in the post. You or a relative or carer will be required to collect relevant bowel preparation medicine at least two days prior to your appointment, this will be discussed when booking your appointment. You will be provided a CT Colonography bowel preparation leaflet whilst collecting your bowel preparation medicine. Please ensure that you read your appointment letter and bowel preparation leaflet carefully. It is important to follow the diet and bowel preparation from the day before your examination, to enable our teams to have a clear view of your bowel. If you require an interpreter – please inform us as soon as you receive your appointment letter, and we will arrange an interpreter for you.
Medication and medical conditions
Please call the Radiology Team on 01279 827179 before you start taking the bowel
preparation if:
- you need to alert us about a medical condition (for example kidney or heart
- problems)
- you have a stoma
- you are on portable oxygen
- you have been told that you are allergic to iodine or an X-ray dye
- you are a diabetic and taking medication called Metformin
- you have significant mobility problems that may affect your ability to cope with
- taking laxatives at home
- you have problems standing or need a hoist to transfer
- you have Glaucoma
- you have prostate problems
- you think you may be pregnant
If you take iron tablets, you should stop taking them 5 days before your appointment.
You should avoid any medication designed to increase the bulk of your motions, ie Fybogel. Otherwise unless directed by your consultant or Doctor that referred you for this test please continue to take all medications as usual prior to this procedure. If you are on the oral contraceptive pill, the bowel preparation may reduce its effectiveness, so continue taking the tablets but use other precautions for the remainder of that cycle.
Stoma patients
If you have a stoma, please call the radiology department as soon as possible and do not follow the preparation leaflet until you have discussed with a member of our team.
Patients with diabetes
If you have diabetes, we aim to give you an appointment earlier in the day. If you take metformin tablets to manage your diabetes, please let us know so that we can arrange a blood test for you – the blood test will be within the seven days before your appointment. If you take insulin to manage your diabetes, you will need to monitor your blood sugars throughout the preparation leading up to your appointment and immediately afterwards, if concerned please speak with the health professional that manages your diabetes. If concerned please speak with a member of our team so that we can provide specific advice about taking your medication and preparing for the examination.
Getting to us
Once you have arrived at The Princess Alexandra Hospital (Hamstel Road, Harlow, Essex,
CM20 1QX), follow the signage to the radiology reception, which is located on the ground floor, green zone. Please let the radiology receptionist know that you have arrived for your appointment.
When should I arrive?
Once you have made your appointment for your examination with our radiology team, you will receive an appointment confirmation letter or telephone call. Please make a note of your appointment date and time. Please ensure that you leave plenty of time to arrive at the hospital, park your vehicle and find the department.
Can I bring somebody with me?
We are unable to accommodate any other people in the scanning room due to health and
safety regulations. You are able to bring an adult with you, who will be able to sit in our waiting area. We suggest that you do not bring children with you to your appointment, unless they are accompanied by another adult, as we are unable to look after them throughout your examination.
The examination: What will happen before the examination?
Before your examination, you will be shown to a private cubicle and be asked to change into one of our hospital gowns. Please keep your belongings with you after you have changed. You will then be shown into either the CT scanning room, or the preparation room, in readiness for your scan. At this point, we will check your identity and explain the procedure to you and answer any questions you may have.
The examination: What will happen during the examination?
As part of the examination, we will need to insert a small cannula (plastic tube) into a vein in your arm to give you a small injection of medication to reduce movements from your bowel, and to give you an injection of contrast medium (a clear liquid that highlights blood vessels on your scan). You may feel a warm sensation as you are given the injection, this is normal. You will be asked to lie on the scan table on your left side. A small, soft plastic tube will be inserted into your rectum (bottom). Through this tube, we pass carbon dioxide gas to gently inflate your bowel. This may make you feel bloated. You will be asked to turn over a few times, this helps us take clear images of the bowel. When enough carbon dioxide gas has been introduced, we start the scan and take the images. The scan table will move slowly through the scanner. You will then be asked to lie on your back, and then on your front, to take further scans. You will be asked to hold your breath for a short time, whilst the scan is in progress. Our team will guide you through this. After the exam, the gas will be let out through the tube into a bag. You will be shown to the toilet to relieve any bloating.
After the examination: What can I expect after the examination?
Immediately after the examination and over the next few hours, you may need to go to the toilet more frequently than normal. If you have had an injection of contrast media, you will be observed in the department for 15 to 30 minutes after the examination before you are able to leave.
When can I start to eat normally again?
You can eat and drink as normal as soon as the examination has finished.
Can I drive after my examination?
If you have had an injection of medication to help relax your bowel, please do not drive for at least 20 minutes after the examination, as this injection can sometimes blur your vision for a short while.
How soon can I return to work?
Some people are happy to go back to work straight after the examination and others prefer to have a few hours at home. It is completely up to you.
When will I get my results?
We are unable to give you the results straight after your examination. Your scan will be reviewed and reported by a consultant radiologist, uploaded to your patient record, and sent to the clinician who referred you for your examination. They will then share your results and the next steps with you.
What is a recall and why may I need one?
A recall is when the radiologist has looked at your previous images from your scan and
would like further images to aid your diagnosis. We may therefore need to ask you to attend a further appointment in the CT department. Please do not be concerned, as radiologists cannot always be present to view and check the images at the time of your initial scan.
Contacting the team
- If you have any further questions about your CT scan or an existing appointment, please contact the radiology department (Monday to Friday, 9am to 4pm) at 01279 827179 and press option 1 for radiology appointments and then option 2 for CT.
- If you have any queries outside of working hours (after 4pm and on weekends), you will be redirected to the main radiology reception. Please note appointment bookings cannot be made during this time.
Your feedback matters
- If you would like to give feedback on your care, please contact our patient experience team at [email protected] or 01279 827211.
- Please contact the communications team at [email protected] if you would like this leaflet in another language or format.