Medical Content Created by the Faculty of the
Harvard Medical School
Tell your doctor if you have ever had an allergic reaction to lidocaine or the numbing medicine used at the dentist's office, or to x-ray dye. Also tell your doctor if you could be pregnant, since x-rays can harm the developing baby. If you have diabetes and take insulin, discuss this with your doctor before the test.
Most people need to have a blood test done some time before the procedure, to make sure they are not at high risk for bleeding complications. If you take aspirin, nonsteroidal anti-inflammatory drugs, vitamin E or other medicines that affect blood clotting, talk with your doctor. It may be necessary to stop or adjust the dose of these medicines before your test.
You will be told not to eat anything on the morning of the test so that your stomach is empty. This is a safety measure in the unlikely case you have a complication, such as bleeding, that might require surgery.