Gastrointestinal bleeding scan

What is a Gastrointestinal Bleeding Scan?

A gastrointestinal (GI) bleeding scan is a specialized imaging test that helps locate the source of bleeding within your digestive tract when other tests have been unable to identify it. This scan is particularly useful for detecting bleeding that is occurring at a slow rate or is intermittent, which can be difficult to locate using other methods.

The test uses a small amount of your own blood cells labeled with a radioactive tracer. These labeled cells circulate throughout your body, and if bleeding is occurring, they will leak out of blood vessels at the site of bleeding. A special camera can detect these labeled cells, helping doctors locate exactly where the bleeding is coming from.

Why Might I Need a GI Bleeding Scan?

Your doctor may recommend this scan if:

• You have evidence of bleeding in your digestive tract (such as blood in your stool)
• Other tests (such as endoscopy or colonoscopy) have not found the source of bleeding
• You have had recurring episodes of GI bleeding
• The bleeding is suspected to be slow or intermittent
• You have unexplained anemia that may be caused by GI blood loss

How Does the Scan Work?

The scan works in the following way:

1. A small amount of your blood is drawn and mixed with a radioactive tracer in a lab
2. These labeled blood cells are then injected back into your bloodstream
3. If there is active bleeding in your digestive tract, these labeled cells will leak out at that location
4. A special camera (gamma camera) detects the radiation emitted by these cells
5. Images taken over time can show where bleeding is occurring and how fast

Preparing for Your Scan

• Generally, no special preparation is required
• You may eat and drink normally before the test unless instructed otherwise
• Continue taking your regular medications unless your doctor tells you to stop
• Wear comfortable clothing
• Inform your healthcare team if you:
  • Are pregnant or breastfeeding
  • Have had recent barium studies (these should be completed at least 3 days before the scan)
  • Have had a recent nuclear medicine scan
  • Have any allergies to medications

What to Expect During the Procedure

Blood Labeling Process

1. You’ll be asked to provide a small amount of blood (about 1-2 tablespoons)
2. A technologist will mix your blood with the radioactive tracer
3. This process takes approximately 20-30 minutes

During the Scan

1. You’ll lie on an examination table
2. Your labeled blood cells will be injected back into your bloodstream through an IV line
3. Immediately after injection, the gamma camera will begin taking pictures
4. Initial imaging will continue for up to 90 minutes
   • You’ll need to lie still during the imaging
   • The camera may move around your abdomen to capture different angles
   • The camera does not produce radiation – it only detects the radiation from your labeled cells

Follow-up Imaging

1. Depending on the findings, you may need additional images:
   • Second set of images at 4-6 hours after injection
   • In some cases, a third set of images at 24 hours after injection
2. These additional images help detect very slow bleeding that might not be visible initially
3. You may be allowed to leave the department between imaging sessions

After Your Scan

• You can resume all normal activities immediately
• There are no dietary restrictions after the test
• The small amount of radiation used will naturally leave your body within a few days
• Drink plenty of fluids to help flush the tracer from your body
• A nuclear medicine specialist will analyze your images and send a report to your doctor
• Your doctor will discuss the results with you at your next appointment

What Do the Results Mean?

• Positive scan: Shows an area where the tracer is collecting and moving through the intestines over time, indicating the site of active bleeding
• Negative scan: No evidence of active bleeding is seen during the imaging period

It’s important to understand that this test can only detect active bleeding at the time of the scan. If bleeding has temporarily stopped, the test may not show the bleeding site.

Limitations of the Test

• The test requires active bleeding at the time of the scan to identify the source
• Very slow bleeding may require delayed imaging to detect
• If no visible bleeding is occurring during the testing period, the scan may be negative even if you have a condition that causes intermittent bleeding

Are There Any Risks?

The GI bleeding scan uses a very small amount of radiation. The benefits of identifying the source of bleeding far outweigh any potential risks from this minimal radiation exposure. Since the test uses your own blood cells, there is minimal risk of allergic reaction.

How Long Will the Entire Procedure Take?

• Initial blood drawing and labeling: 20-30 minutes
• Initial scanning: Up to 90 minutes
• Possible additional scanning at 4-6 hours: 30-45 minutes
• Possible final scan at 24 hours (if needed): 30-45 minutes

The entire process may be spread over 24 hours depending on your specific situation.

If you have any questions or concerns about your gastrointestinal bleeding scan, please discuss them with your healthcare provider.