The accuracy of technetium-99m-labeled red cell scintigraphy in localizing gastrointestinal bleeding.

OBJECTIVE: To evaluate the success of technetium-99m-labeled red blood cell scintigraphy in localizing the site of gastrointestinal bleeding, and to identify the clinical and technical factors that contribute to scan accuracy.

METHODS: A retrospective review was conducted of all patients who underwent a tagged red blood cell scan for the evaluation of gastrointestinal bleeding at our institution from 1981 to 1991.

RESULTS: Of a total of 153 patients, 90 (59%) had positive scans, whereas, in 63 (41%), they were negative. Of the 90 patients who had positive scans, it was possible to assess scan accuracy in 44 who had corrective surgery or an additional diagnostic procedure which definitively localized the site of bleeding. Of those 44 patients, the correct bleeding site was identified by red blood cell scanning in 33 patients (75%) overall and in all six patients with a left colon bleeding site. In this group of 44 patients, 22 scans were positive within 2 h, and of these the scan was accurate in localizing the bleeding site in 19 of 22 (86%). When the three subjects with upper gastrointestinal bleeding were excluded, the scan was positive in 100% of the remaining 19 patients.

CONCLUSION: The technetium-labeled red blood cell scan is a reliable tool for the assessment of unexplained lower gastrointestinal bleeding when the scan is positive within the first 2 h, and an upper gastrointestinal source has already been excluded.