Iodinated
Contrast
Indications
Iodinated contrast media (sometimes called "X-ray
dye," "Contrast, " or "IVP dye"
is a very important part of your imaging exam when needed.
We use contrast for CT scans, or IVP exams where it is
administered in the vein (intravenous or IV). For some
exams it is essential and the exam will be less accurate
without it. Your referring doctor or your radiologist
will know best when to use or omit IV iodinated contrast
for your exam.
Contraindications
There are a few situations in which to avoid using or
obtain special preparation for using iodinated contrast.
One of these is poor kidney function because after the
exam your kidneys have the role of taking the contrast
out of your blood stream and excreting it into your urine.
If the kidneys are functioning weakly, they may have trouble
removing the contrast and may be further damaged by it.
In normally functioning kidneys there is no damage. In
patients that have diabetes or other reason that they
might have limited kidney function, a blood test may be
needed in advance to make sure they are functioning well
enough to do the exam with contrast.
As with any medication, a patient can have an allergy
to the contrast or, more often, may have an "allergic-like"
reaction. Reactions to contrast are typically mild, consisting
of flushing, nausea, hives, or itching, but they can rarely
be severe and even life-threatening. Fortunately, in the
case of a severe reaction, there is a simple, fast and
effective treatment with a small dose of epinephrine.
In patients with a previous history of a reaction to IV
iodinated contrast, we can give the patient a small series
of doses of medicine to take orally the day before the
exam to minimize the chance of reaction. All contrast
for CT scans and for IVP studies contains iodine. There
is a difference between ionic and nonionic contrast. Nonionic
contrast is generally better tolerated with fever side
effects. All the facilities for whch we provide services
use nonionic contrast.
The Iodine Allergy Myth
Some people that have a history of allergy to shellfish,
a history of a previous reaction to IV iodinated contrast,
or a history of a reaction to a topical iodine solution,
have been told that they have "iodine allergy."
This is actually not correct. "Iodine Allergy"
doesn't really exist. Shellfish allergy is not a contraindication
to iodinated contrast because the allergy is entirely
unrelated. This is a longstanding myth even within the
medical community and is difficult to dispel. Sensitivity
to Betadine® and other Iodine-containing solutions
is unrelated to reactions to iodinated radiographic contrast
agents.
|
