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What can help differentiate between an upper and a lower source of bleeding?
| Feature | Upper GI Bleeding | Lower GI Bleeding |
|---|---|---|
| Anatomy | Esophagus to ligament of Treitz (duodenum) | Below ligament of Treitz (jejunum to rectum) |
| Common Causes | Peptic ulcers, esophageal varices, gastritis, Mallory-Weiss tear | Diverticulosis, hemorrhoids, colon cancer, IBD, angiodysplasia |
| Color of Blood | Dark red, black (melena), or coffee-ground appearance | Bright red (hematochezia) or maroon-colored |
| Hematemesis (vomiting blood) | Present (hallmark) | Absent |
| Melena (black, tarry stool) | Common (suggests digestion of blood) | Rare |
| Hematochezia (fresh blood per rectum) | Rare, may occur if massive UGI bleed with rapid transit | Common |
| Nasogastric (NG) Aspirate | May show blood or coffee-ground fluid | Usually clear if bleeding is from below |
| BUN:Creatinine Ratio | Elevated (>20:1), due to digestion of blood proteins | Typically normal |
| Initial Diagnostic Test | Upper endoscopy (EGD) | Colonoscopy |
| Timing of Bleeding | Often associated with vomiting or postprandial | Often associated with bowel movements |
Additional Clues:
- Massive, brisk hematochezia may still be from an upper GI source — always consider upper endoscopy first in unstable patients.
- Anoscopy or sigmoidoscopy may be useful for suspected anorectal bleeding (e.g., hemorrhoids).
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).
Summary
- Hematemesis = Upper GI
- Melena = Likely Upper GI
- Bright red blood per rectum = Likely Lower GI, unless massive UGI bleed
- Elevated BUN/Creatinine ratio may favor upper GI source
