Nuclear Gastrointestinal Scans By Jonathan Gotfried, MD, Lewis Katz School of Medicine at Temple University Reviewed / Revised Mar 2023 View Patient Education Bleeding Scans Gastric Emptying Meckel Scans Topic Resources Meckel Scan Showing Meckel... Bleeding Scans Bleeding scans use 99mTc-labeled red blood cells, or occasionally 99mTc-labeled colloid, to determine the origin of lower gastrointestinal hemorrhage before surgery or angiography.