Scintigraphic detection of gastrointestinal bleeding: a review of current methods.

Recent experience with radionuclide imaging has provided the clinician with several techniques to noninvasively detect and locate sources of gastrointestinal hemorrhage. These tests can be rapidly performed and often in an ICU setting. One method used Tc-99m sulfur colloid which, in an animal model, has been shown to detect acute bleeding at rates as low as 0.1 ml/min. However, because the tracer remains in the blood for a short period of time, it may be suboptimal for identifying patients with intermittent bleeding. Tc-99m red cells is a tracer that remains within the blood and permits detection of both acute and intermittent bleeding. With tagged red cells, sites of bleeding from both the upper and lower gastrointestinal tract can be found. Both of these techniques can provide important information in the patient with suspected active gastrointestinal bleeding and aid the clinician in more effective management including the use of invasive diagnostic and therapeutic techniques.