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| TOPIC: Intravascular (through a vein or artery) Contrast Media In Radiology (with reference to Iodine-containing Contrast Media) | Why Would I Need Contrast Media In My Radiology Examination?A number of investigations in Radiology will require administration of this contrast into your body via a vein or artery. A common example is the intravenous urogram. There are two type of iodine containing contrast media, and these are either ionic or non-ionic (with regards to its chemical structure). Normally, only the bones, and air are well seen on plain radiographs (x-rays). To delineate the passage of urine or blood flow in the blood vessels, contrast media that is iodine-containing is introduced to increase the density of the urine or blood. They will appear “white” on the films, just like your bones on x-rays). | | Are there special preparations or precautions? | If you have none of the following conditions, you would probably only need to fast (no food or drink) for 4-6 hours prior to the examination. If you have the following conditions, you will need to take special precautions and be aware of the slightly increased risks: Definite History of Allergy Asthma Previous reaction to contrast media Previous reaction to drugs Heart conditions Multiple Myeloma or myelodysplastic syndromes or severe diabetes (please do not dehydrate yourself by restricting your water intake) The very old (> 65 years) and the very young < 6 months>
| | What are some of the Potential Complications or Risks? | Despite what may appear as alarming in the descriptions below, the incidence of the moderate to severe reactions are extremely low. Your doctor would have considered the benefits versus risk ratio when they recommended certain investigations for you. It may be more risky to cross a busy road then to undergo an examination that may help to diagnose and your doctor to treat your condition better. Contrast medium is like other drug you may be more familiar with. In fact, the new generation of iodine containing contrast media are very safe. Even so, like all drugs, (including the commonly taken Panadol/Paracetamol), there is a potential risk of reaction to the contrast media. These are classified into mild, moderate and severe. With the non-ionic contrast media, the incidence of reactions is markedly reduced. Most of the reactions are mild, transient and require no treatment, and the majority will occur within the first 20 minutes of the injection. There are a small proportion of delayed reactions, which may occur up to a day or two after the injection. Examples include: Mild: Nausea, vomitting and/or both. Generalised transient warmth felt throughout the body. (akin to flushing) Rashes which may be transient or lasting a few days. An antihistamine will be given. Sneezing, “running” nose.
Moderate: Difficulty breathing, (it may be like asthma): immediate treatment given. Rarely, this is so severe to be life threatening. Hypotension: Sudden drop in the blood pressure: Immediate treatment given. Usually this is transient and not severe.
Severe and life threatening ( VERY RARE with modern iodine containing contrast medium): Anaphylactic shock. (an unpredictable reaction) | | What do I do after receiving intravenous contrast media? | This would depend on the procedure that was done. However, in general, you are encouraged to drink plenty of fluids and maintain hydration. The majority of the iodine containing contrast medium would be excreted into your urine within 4 hours after the examination.
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