Diagnostic utility of nasogastric tube aspiration and the ratio of blood urea nitrogen to creatinine for distinguishing upper and lower gastrointestinal tract bleeding
American College of Gastroenterology's 2016 clinical guidelines for treating lower gastrointestinal (GI) tract bleeding recommends evaluating nasogastric tube aspiration and the ratio of blood urea nitrogen (BUN) to creatinine to differentiate upper from lower GI bleeds.
