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CT Contrast Omnipaque Contrast Injection – Patient Information

This page contains information on Omnipaque (Iohexol) which is a contrast (dye) used during CT scans. Further information about Omnipaque is available in the manufacturer’s patient information leaflet – please ask us if you would like a copy.

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What is Omnipaque?

Omnipaque is a clear, colourless iodine-based liquid. It is used to make the images clearer and define different structures in the body during a CT scan to help with diagnosis. A radiologist (a specialist doctor trained in studying scans and X-rays) will have approved a protocol to carry out your scan. If you need Omnipaque, a radiographer will discuss this with you when you come for your scan. You can also call and speak to a radiographer before your scan on 0207 467 4317.

Asking for your 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.

How is it given?

Omnipaque is injected into one of your veins via a needle or a cannula (a soft, thin plastic tube) during your scan. The cannula is inserted through your skin into a vein using a needle. Once the cannula is in place the needle is removed, leaving the small, thin plastic tube in the blood vessel. This should be comfortable and will only be in place until your scan is finished.

Are there any side effects?

Omnipaque is not suitable for everybody. The radiographer or radiologist will decide if it is appropriate for you.

In people who have severely reduced kidney function, Omnipaque should only be used with radiologist approval. This group of patients cannot excrete Omnipaque through urine, which may cause problems.
It is important that you tell the radiographer before your scan if you have any history of kidney problems. Under the Royal College of Radiologist guidelines, patients 65 or over will have their kidney function
tested on the day, unless consent is not given.

Please also let us know if you have had a previous allergic reaction to a contrast agent or iodine.

Omnipaque may cause side effects in some people but these are usually mild and short lasting. Some of the more common side effects include:
• Hot flush
• Metallic taste in your mouth
• Feeling as though you want to pass water (wet yourself) – you won’t, it is just a sensation

Serious allergic reactions are rare, however please seek immediate medical attention if you have any of the following after leaving the hospital:
• Swelling of the face, mouth, hands, feet or throat
• Difficulty breathing or swallowing
• Fainting
• Coughing/wheezing/sneezing
• Eye irritation
• Rash/hives/itchy red skin

Allergic reactions to Omnipaque contrast agents are very uncommon but do occur. Most occur during the injection or within the first hour following administration; however some can occur up to several days later. If a reaction was to occur during your scan the hospital has the team and the medicine to help with this. If a reaction occurs after you have left the hospital we would advise you to attend an A&E department.

If you have any concerns about side effects, please speak to the staff caring for you.

Occasionally the injection may leak out from the vein to the tissues under the skin – this is known as extravasation. If this happens, you will experience a stinging sensation where the contrast has gone into the tissue, which can be painful. If you would like more information about this please ask a member of staff for our leaflet, Contrast injection leak guidance (extravasation).

Contact us

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.