I. Indications

  1. Acute Lower Gastrointestinal Bleeding without obvious source based on Colonoscopy
  2. Most useful in slower Gastrointestinal Bleeding (<0.4 ml/minute)
  3. Often used to preselect patients with non-brisk Lower Gastrointestinal Bleeding for angiography

II. Description

  1. Radionuclide scan with Technetium 99m-labeled red cells
  2. Labeled Red Blood Cells circulate for 48 hours (allows for repeat scanning)
  3. Identifies sites of GI Bleeding via gamma camera scan
  4. Detects bleeding down to rates as low as 0.1 ml/min

III. Protocol

  1. Scan should be verified by second method
    1. Angiography (most commonly follows tagged scan)
    2. Endoscopy
    3. Surgery
  2. Scan localization is 78% accurate when verified
  3. Do not base bowel resection solely on tagged cell scan
    1. Results frequently in recurrent bleeding (42%)
    2. Hunter (1990) Am J Surg 159:504-6

IV. Efficacy

  1. Identifies Lower GI Bleed site in 26-78% of cases
  2. Most sensitive early in scanning (first 2 hours)
  3. Positive scan predicts higher morbidity and mortality

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