Your CT Enterography scan

CT Scanning Department
Colchester Hospital
Tel: 01206 742 144

Please read this leaflet carefully before your appointment

What is a CT scan?

A CT scan uses X-rays and a computer to construct special cross-sectional images of a designated area of your body.

Imagine your body as a sliced loaf of bread. You would then be able to take out individual slices to view the internal structures as well as producing 3D reconstructions of your body.


Female patients

Female patients aged 12 to 55 years (or if you are having regular menstrual cycles) – if either of the following statements apply to you, please contact us because a new appointment will need to be made, if:

  • this appointment is not within 10 days of the start of your last period,
  • there is a possibility that you may be pregnant.


Blood tests

To ensure we perform your scan as safely as possible you need to have had a blood test within the last six months to check your ‘serum creatinine’ levels.

  • If you have not had this test we will have sent you a form with this letter.
  • If you have not received a form it means that we already have up-to-date results for you.
  • If you have a form, please have the blood test before your scan or it may be cancelled or rescheduled.


Diabetic patients

If you are on metformin tablets please do not take them on the day of your scan. The radiographer who performs your scan can tell you when you can resume taking them.

If you have a personal use insulin pump this will need to be removed before you enter the CT scan room and kept outside of the radiation area.


Risks and benefits

All medical procedures carry some risks. With this procedure, that risk would be radiation. All of our equipment is state-of-the-art and well within its natural working life expectancy. It has routine service checks and is maintained with an ongoing quality assurance programme.

Radiation doses are kept as low as possible. We always weigh any risks to the benefits that may be gained from any procedure before going ahead. Your GP and our radiology team will have agreed that the benefits to you will outweigh any risk of having this procedure. If you have any questions or do not wish to proceed, please contact us as soon as possible or speak to a member of staff.

If you have had any X-ray procedure where you were injected with contrast and had a reaction to the contrast or if you have an allergy to iodine, please inform the radiographer on arrival.


Do I need special preparation?

  • You may drink clear fluids.
  • Do not eat for 5 hours prior to your appointment.
  • You will be given a special liquid to drink over the two hours before your appointment time. This is required to highlight your small bowel (intestines).
  • Take any regular medicines as normal.


Where do I go when I arrive at the hospital?

  • Enter through the main entrance of Colchester Hospital.
  • Continue down the main corridor. Just before you get to the bottom of the corridor to the T-junction, you will see a sign on your left with ‘X-ray (Beta Suite)’ by the entrance.
  • Proceed through the doors and up to reception with your appointment letter.

What will happen when I arrive?

You will be asked to remove all your clothing except your pants/knickers and shoes, and put on an X-ray gown. You may bring your own dressing gown to wear over this and bring your slippers to wear instead of your shoes, if you wish.

You should then sit in the waiting area until your name is called.

You will be called into the scanning suite as close to your appointment time as possible. The procedure will be explained to you and we will check for possible allergies.


How is the scan performed?

  • The radiographer will explain the procedure to you.
  • A cannula (small flexible tube) will be inserted into a vein in your arm.
  • A muscle relaxant will be injected through the cannula in your arm. This reduces any spasm in the bowel. (This injection can cause blurred vision for about 20 minutes. Please ensure your vision has returned to normal before leaving the department).
  • A tube will be attached to the cannula in your arm through which the contrast (X-ray dye) will be injected. This is to highlight the blood vessels being examined. (If you are allergic to iodine or have had an allergic reaction to X–ray dye in the past, please inform the radiographer prior to any injection).
  • You will then be moved into the scanner. You will be moved in and out at different times as the contrast is injected and the pictures are taken.
  • It is important that you follow the instructions closely and remain as still as possible during the scan.

Contrast media information

Your doctor has requested a computerised tomography (CT) examination that requires an injection of contrast into your bloodstream. This injection helps the radiologist to assess your scan in more detail.

The contrast medium is usually injected through a cannula, which is positioned into a vein in your lower arm or the back of your hand.

When the contrast medium is injected, you may experience a warm sensation all over your body, a metallic taste in your throat and the feeling that you are wetting yourself. These are only temporary and wear off after a few seconds.

The contrast medium is a compound containing iodine. The specific names of those commonly used at this hospital are Omnipaque and Visipaque.

Contrast media are usually very safe, although there is a small risk of contrast leaking from the vein into the surrounding tissues or a possible reaction to it. The most common side effects include nausea and vomiting. An allergic reaction is rare, affecting from one to 10 patients in 10,000.

Will it be painful?

The insertion of the cannula into the vein may cause some discomfort. This is no worse than having a routine blood test.

The remainder of the examination is painless.

How long will I be at the hospital?

From the time of your arrival until the completion of your examination will be approximately 2 hours 30 minutes. On occasions this may be longer due to emergencies taking priority in the scanner.

After the examination

You may resume normal activities.

Please note: Ensure your vision has returned to normal if you intend to drive home. In the rare event that following the examination you develop painful blurred vision, you must attend the Emergency Department for an assessment.

If you have had the contrast injection

Although extremely rare, some people have a delayed allergic reaction to the contrast. If this should happen and you have not left the hospital, let someone in the department know. If you have already left the hospital, you should contact your GP if you have any adverse symptoms, or go straight to the Emergency Department.

Please inform our department of any reactions on 01206 742 144.

How do I find out the results?

A copy of the results will be sent to the doctor who referred you for the examination. If you were sent by a consultant, you should receive a follow-up appointment from the outpatient clinic.

Additional information

If you have any questions about your examination please contact the radiology department. The number can be found at the beginning of this leaflet.

Car parking

Click here for more parking information.



Anyone with questions about parking at Colchester Hospital can email

Alternatively, Colchester Park and Ride is located opposite the JobServe Community Stadium (at J28 of the A12). The buses stop outside the back of the hospital and from 5.30am to 9pm, Monday to Friday and 7am to 7pm on Saturday.
For more information call 0345 743 0430 or visit the Essex Highways website.

Your photographic records

As part of your treatment, a photographic record may be made, such as X-ray(s), clinical photographs or digital images, which will be kept confidentially in your health records and seen only by people involved in your care or quality checking.

They are also extremely important for teaching or medical research so we may ask for your written consent to use your images, in which case your personal details will be removed so you cannot be identified.

Your NHS number

When you attend hospital you will be asked for your NHS number and other information, such as your address. Please be patient with this procedure – it is to ensure our records are kept up to date and to protect your safety. If you do not know your NHS number, please don’t worry, you will still receive care.

We value your feedback

To give us feedback on your visit or healthcare experience, please visit ‘Your views matter’, or speak to a member of staff on the ward or department you are in.


A map showing patients how to get to the C T department

© East Suffolk and North Essex NHS Foundation Trust, 2021.
All rights reserved. Not to be reproduced in whole, or in part,
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