What can help differentiate between an upper and a lower source of bleeding?
Characteristics of a UGI source include the following:
• History includes prior ulcer, chronic liver disease, or use of aspirin or NSAIDs.
• Symptoms include nausea, vomiting, or hematemesis.
• Nasogastric (NG) aspirate contains blood or “coffee grounds” material (NG aspirate positive for bile but negative for blood does NOT rule out a UGI source).
• Serum blood urea nitrogen/creatinine ratio greater than 33 is highly suggestive.
• Melena indicates a UGI source (can also be seen in LGIB, specifically with colon cancer).
Characteristics of an LGI source include the following:
• Absence of UGI symptoms or risk factors indicates an LGI source (not always the case; one recent randomized controlled trial showed that the 15% of UGIB presenting as LGIB did not have UGI symptoms).
• Bright red or maroon blood per rectum indicates an LGI source (although can be seen in brisk UGIB).