Sulfur Colloid vs Tagged Red Blood Cells for Gastrointestinal Hemorrhage

Red blood cells and sulfur colloid are tagged with ^99mTc-tagged red blood cells remain intravascular and are better at detecting intermittent bleeding. Preparation of tagged red blood cells, however, is a bit involved.

Sulfur colloid is easy to prepare and readily available. It is taken up by the reticuloendothelial system, providing great target to background contrast as long as the bleeding site is not over the liver or spleen. The speed of clearance (vascular half-life=3.5 minutes) is also a disadvantage when it comes to intermittent bleeding.

References

Mettler FA and Guiberteau MJ. Chapter 8. In Essentials of Nuclear Medicine Imaging. Fifth Edition. Saunders, Philadelphia. 2006. pp 215-216.