Iodinated intravenous contrast material is an agent that contains iodine, a substance commonly used in diagnostic radiology. When injected into a patient's vein, iodinated intravenous contrast material is readily seen on X-ray, allowing for better visualization of vessels and internal organs to assist in the accurate diagnosis of a patient's condition.
Iodinated intravenous contrast material is frequently used during CT scans, interventional radiology and neuroradiology procedures, as well as intravenous pyelograms (IVPs). Cardiologists also frequently use this material when performing cardiac catheterizations. Other examinations such as genitourinary studies (e.g. cystogram/VCUG, retrograde urethrogram, hysterosalpingogram), myelograms, and arthrograms also use iodinated contrast material. In these instances, the contrast material is not injected intravenously but rather into the genitourinary tract, spinal canal, or bony joints, respectively.
If you are receiving iodinated contrast material intravenously for an intravenous pyelogram (IVP) or a CT scan, you should not eat or drink anything for four hours prior to your examination. If you have a known allergy to iodinated contrast material, you should discuss this with your doctor prior to your examination. Even if the contrast material is not administered intravenously, you may be given a special preparation of a steroid and Benadryl/diphenhydramine to be started a day before the examination. Additional preparation may be required for patients with diabetes or kidney disease (see below).
Although rare, there are some risks involved with the use of iodinated intravenous contrast. You should tell your doctor and the radiology technologist about any known allergies or reactions you have to iodine or intravenous contrast. In such cases, you may be given a special preparation of a steroid and Benadryl/diphenhydramine to be started a day before the examination. In addition, inform your doctor and the radiology technologist about any chronic medical conditions you have, such as asthma, diabetes, or kidney disease. When the contrast material is injected, some patients report feeling a warm sensation and/or a metallic taste in their mouth. These side effects are not dangerous and usually pass within a minute or two. Some patients may experience sneezing and mild nausea, and, less frequently, vomiting. There is also the possibility of a mild itching sensation. If the itching persists or is accompanied by hives, notify the radiology technologist so the problem can be treated with medication. In very rare instances, a patient may become short of breath and experience swelling in the throat. These symptoms may be indications of a more serious type of reaction to the contrast material. They should be reported immediately to the radiology technologist so the test can be stopped and appropriate treatment provided. If you do experience a moderate to severe contrast reaction, the doctor may keep you for a period of observation afterward.
Patients with diabetes who take oral glucose lowering medication (e.g. glucophage or metformin) may be required to have blood tests or adjust their medication dosage before intravenous contrast is administered. In these instances, you should discuss the situation with your doctor prior to the examination so the proper course of action can be taken.
Since the kidneys excrete intravenous contrast material, patients with kidney disease receive a special evaluation prior to its administration. Laboratory studies are often performed on patients with kidney disease prior to the administration of intravenous contrast, if such studies have not already been recently obtained. In addition, special intravenous hydration may also be required. If necessary, these additional procedures will lengthen the time the patient spends in Radiology, but may be necessary to ensure the intravenous contrast can be administered safely. Alternatively, if the potential risks are determined to outweigh the benefits, a patient with kidney disease may not be given intravenous contrast.