Overview

A Gastrointestinal Bleed (GI Bleed) Scan is a special nuclear medicine test that demonstrates the location of bleeding occurring in the digestive tract. It comes in handy particularly when the bleeding is concealed, slow, or difficult to detect using regular examination procedures such as endoscopy or colonoscopy. 

The test will involve a small sample of a radioactive material, which is normally Technetium-99m tagged red blood cells (99mTc-RBC). This allows doctors to know the location of the blood flow and identify points where it evacuates into the gut. Since the labeled cells remain in circulation, the scan is able to detect bleeding that occurs occasionally and would not be revealed in other tests.  

GI bleed scan is not painful, it is safe, and quite effective in search of a slow bleed. It is a valuable instrument for emergency departments and hospitals. The test can be advised when physicians are unable to locate the cause of gastrointestinal bleeding using other tests. The findings can be used to further plan subsequent treatment, radiology treatments, or surgery.

What is a GI Bleed Scan?

GI Bleed Scan is a nuclear medicine test procedure used to detect active bleeding in the gut.  

In the test, a sample of the patient's blood is drawn, and the red blood cells are marked with Technetium-99m, a safe radioactive tracer. The marked cells are then reintroduced into the blood.  

A gamma camera is used to capture images of the abdomen at different times to trace the motion of the cells that have been labeled. In case the bleeding is occurring, the tracer will not be within the normal blood vessels, and a doctor can observe the place of the bleeding. The scan has the ability to identify very slow blood loss (approximately 0.1 mL/min), and this is not as big as what the angiography is capable of detecting.

When is a GI Bleed Scan Recommended?

Doctors  may recommend a GI bleed scan in situations such as:

• Gastrointestinal occult or hidden bloodshed.  
• Active bleeding GI, unknown location.  
• Sudden reduction in the level of hemoglobin.  
• Intermittent or unaccounted anemia.  
• Potential characteristics of lower gastrointestinal bleeding.  
• Bloodless bleeding not discovered through endoscopy or colonoscopy.  
• Post-surgery assessment of the gastrointestinal tract in case of gastrointestinal bleeding.  
• Bleeding, transient bleeding, particularly in elderly patients.

What Does a GI Bleed Scan Reveal?

A GI bleed scan helps doctors: 

• Discover active gastrointestinal bleeding.  
• Approximately locate the bleeding.  
• Determine whether the bleeding is persistent or discontinuous.  
• Ordering an angiography, endoscopy, or surgery.  
• Observe gastrointestinal bleeding that is continuous or repeated.  

Advantages of GI Bleed Scintigraphy

• Non-invasive and painless test.
• Able to locate small bleeding (approximately 0.1 mL/min) that is very slow.  
• Permits lab not only intermittent bleeding but also permits delayed imaging.  
• No bowel prep and sedation required.
• Useful where other imaging tests fail to identify the source.  
• Low radiation exposure. 

Limitations of the Test

Despite its usefulness, the GI bleed scan has certain limitations:

• It can not be used to detect the precise location of bleeding (such as ulcers, tumors, and diverticula)  
• It localises the bleeding, although it might not necessarily reveal the precise anatomical location.  
• It is not very helpful when there is no active bleeding during imaging.  
• Endoscopy, CT angiography, or conventional angiography may still be required as follow-up tests.  

Who Interprets the Scan?

A radiologist trained in nuclear imaging or a nuclear medicine physician reads the images. The referring doctor receives the results and consults with the patient and their symptoms, as well as laboratory work and other radiographies, to determine the most relevant treatment.

Conclusion

Gastrointestinal Bleed (GI Bleed) Scan is a nuclear medical examination that is of value in detecting and localizing active bleeding in the digestive tract. The scan of the blood flow and indications of abnormal accumulation of blood in the gut are done using Technetium-99m labeled red blood cells.  

It is particularly useful in the case of intermittent/slow bleeding, which can go unnoticed in other tests. The GI bleed scan is highly sensitive and does not involve any pain or discomfort; thus, it can effectively be used to inform future studies and treatment choices.  

It can be used together with other diagnostic methods to control gastrointestinal bleeding in a better way and enhance the outcomes of patients.