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Medical Imaging

Nuclear Medicine > Exams & Procedures > Gastrointestinal Bleeding

This test is done to determine if you are bleeding from your intestines and determines the location of the source of the bleed.

The test involves labeling your red blood cells with a radioactive tracer. To label your blood you are given two injections 20 minutes apart. The first injection prepares your blood for the radioactive tracer. The second injection is a small amount of radioactive tracer that will allow us to take pictures of the blood distribution in your body.


  • You should have nothing to eat or drink six hours prior to the test.
  • Bring a list of all medications and supplements you take. This includes vitamins, herbal remedies, and holistic medications.
  • Do not bring children or pregnant women with you to the department. We do not want to expose them to unnecessary radiation.
  • Any of these procedures is subject to change according to the nuclear medicine physician. The duration of the tests is a rough estimate. Please be aware that the time may be lengthened if a scan has to be repeated, if emergency cases are brought to the department or due to unforeseen circumstances.

About the Procedure

Blood Labeling - 30 minutes.
Pictures - 60 minutes with the possibility of delayed images.

  • A technologist will briefly explain the test to you and try to answer any questions you may have about the procedure.
  • A technologist will ask you a few questions about your medical history and medications.
  • You will receive an injection of a blood labeling drug, which has no side-effects, into a vein and then wait 20 to 30 minutes.
  • The technologist will ask you to lie down on the bed and the camera will be positioned above your abdomen.
  • You will receive the injection of the radioactive tracer into a vein.
  • Pictures will be taken for one hour.
  • Delayed images may be required two, four, or 24 hours after the injection for five minutes each.