RESUMO
PURPOSE: Technetium-99m-labeled red blood cell scintigraphy, commonly used in the evaluation of acute lower gastrointestinal hemorrhage, often fails to demonstrate a source of bleeding. It would be helpful to characterize a subset of patients more likely to have a positive scan. This study was undertaken to determine whether hemodynamic instability can predict tagged red blood cell scan positivity. METHODS: The records of 50 consecutive patients who underwent tagged red blood cell scanning for the evaluation of acute lower gastrointestinal bleeding were reviewed retrospectively. RESULTS: Patients presenting with a heart rate >100 beats per minute or a systolic blood pressure <100 mmHg up to 24 hours before undergoing tagged red blood cell scanning were considered hemodynamically unstable. Thirteen of 21 unstable patients (62 percent) had positive scans, whereas only 6 of 29 stable patients (21 percent) had positive scintigraphy (odds ratio, 6; 95 percent confidence interval, 1.79-22.1). CONCLUSIONS: Hemodynamic instability in the setting of acute lower gastrointestinal bleeding may be a predictor of positive tagged red blood cell scanning. Incorporating this into the diagnostic algorithm used to evaluate patients with acute lower gastrointestinal bleeding may allow physicians to reserve red blood cell scintigraphy for patients who have demonstrated transient hemodynamic compromise.
