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What is iodinated contrast?
Iodinated contrast is contrast media that contains iodine and is sometimes called "x-ray dye." It is a colourless liquid which contains iodine and is injected to allow your organs to be more clearly seen during the scan. It does not "stain" your body and will normally be passed out in the urine.
Will there be any discomfort?
You will need to have a cannula ("drip") put into a vein in your arm so that you can have the injection as part of your scan. This will be done by one of our clinical staff -a radiologist, radiographer or nurse.
What happens during the injection?
Prior to the scan, our clinical staff (radiographer or nurse) will discuss the examination with you, including the need for the injection of iodinated contrast and any risks specific to you. You will be provided with the opportunity to ask questions.
When having an injection of iodinated contrast in the artery or vein, most patients will not notice any sensations, but some patients notice a very warm feeling that spreads throughout their body for about 20 seconds during and after the injection. This is often concentrated around the groin area and you may think that you are passing urine but you are not. It is very common and goes away quickly. Occasionally, patients feel nauseous (like vomiting) for a short time during and after the injection.
The injection takes between 10 and 30 seconds if you are having it into a vein in your arm for a CT scan. If you are having an angiogram, you will probably have multiple injections (but only one needle) through a thin plastic tube inserted in your groin during your procedure.
Are there any after effects from the injection?
Most people feel fine after an injection of iodinated contrast. However, if you become or feel unwell or notice anything wrong, go to your nearest emergency department or GP. Serious reactions to contrast very rarely occur more than 1 hour after the contrast is given.
What happens after the examination?
You will be able to eat and drink as normal following the scan.
If you are diabetic or have kidney problems before the scan, our staff will provide you with clear written instructions on ways to look after yourself following the injection of iodinated contrast. This includes information such as; arranging a follow-up appointment with your GP to check how well your kidneys are working before you re-start your diabetic medication if you had to stop it.
What are the benefits?
Contrast media will provide additional information to the radiologist (specialist doctor) who is going to interpret your imaging (the pictures taken when you have your scan). This additional information will often lead to a more accurate diagnosis.
Are there any risks?
In referring you for this procedure, your doctor is of the opinion that the benefits of this scan for you are greater than the risks of having the injection of iodinated contrast.
Please inform the staff before the procedure if you:
- have any allergies;
- are or suspect that you may be pregnant;
- are asthmatic;
- are diabetic;
- have any kidney problems; or
- take diabetic medication that contains Metformin.
The risks and complications with contrast media can include but are not limited to the following.
- Leakage of contrast media outside the blood vessel. Mild leakages can be treated with ice, compression and go away on their own without further treatment. If severe or if you experience increasing pain, increasing swelling or enlarging redness you must see your GP or go to your nearest hospital emergency department.
- Kidney related side effects: If you already have severe kidney disease or diabetes or both, iodinated contrast media can temporarily make your kidney function worse. However, in the majority of cases, this will return to normal.
- Allergic reactions. This can occur within the first 5 minutes and have been known to occur up to a week after the injection. The most serious reactions usually occur within the first 10 minutes.
- Minor reactions occur in up to 1 in every 100 patients, usually go away on their own and do not require any special treatment. The reactions include face flushing, mild nausea and/or vomiting and mild itch.
- Moderate reactions occur in less than 1 in every 1000 people. These often need drug treatment and symptoms include prolonged vomiting, a generalised rash, or swelling of the face, mouth or throat, making it harder to breathe and swallow.
- Severe reactions including death occur in fewer than 1 in 100,000 people. These require emergency medical treatment and often admission to hospital for a period of observation.
These risks are minimised by asking the questions in this form.
In the event that you may experience one of these side effects, the imaging practice will have personnel who are suitably trained and appropriate medication and equipment to treat a contrast reaction.
If you have abnormal kidney function and it is decided that you need contrast media, you may need a few hours of clear fluid given intravenously (directly into a vein) through a “drip” before your procedure to reduce the chance of your kidney function getting worse. Intravenous fluids may be continued after the procedure as well.
References: This information is sourced from the RANZCR Contrast Administration Guidelines and is reproduced with permission of the Royal Australian and New Zealand College of Radiologists (RANZCR) Iodinated Contrast Media Guideline. Sydney: RANZCR; 2018.
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