II. Indications
- Acute Lower Gastrointestinal Bleeding without obvious source based on Colonoscopy
- Most useful in slower Gastrointestinal Bleeding (<0.4 ml/minute)
- Often used to preselect patients with non-brisk Lower Gastrointestinal Bleeding for angiography
III. Description
- Radionuclide scan with Technetium 99m-labeled red cells
- Labeled Red Blood Cells circulate for 48 hours (allows for repeat scanning)
- Identifies sites of GI Bleeding via gamma camera scan
- Detects bleeding down to rates as low as 0.1 ml/min
IV. Protocol
- Scan should be verified by second method
- Angiography (most commonly follows tagged scan)
- Endoscopy
- Surgery
- Scan localization is 78% accurate when verified
- Do not base bowel resection solely on tagged cell scan
- Results frequently in recurrent bleeding (42%)
- Hunter (1990) Am J Surg 159:504-6 [PubMed]
V. Efficacy
- Identifies Lower GI Bleed site in 26-78% of cases
- Most sensitive early in scanning (first 2 hours)
- Positive scan predicts higher morbidity and mortality