Signs of Upper GI Bleeding in Stool
The primary sign of upper gastrointestinal bleeding in stool is melena, which appears as black, tarry stools. 1, 2
Key Stool Presentations of Upper GI Bleeding
- Melena: Black, tarry stools that occur when blood from the upper GI tract is digested as it passes through the intestines 1
- Hematochezia: Bright red blood per rectum, which can occasionally occur with massive upper GI bleeding that passes through the digestive tract rapidly 1, 2
Clinical Context and Associated Symptoms
Upper GI bleeding typically presents with:
- Hematemesis (vomiting fresh red blood) 1, 2
- Coffee ground emesis (vomiting altered black blood) 1, 2
- Melena (black tarry stools) 1, 2
Patients who present with both hematemesis and melena generally have more severe bleeding than those with melena alone 1, 2.
Severity Assessment
The appearance of stool can help assess bleeding severity:
- Melena alone: Generally indicates less severe bleeding 1
- Melena with hematemesis: Indicates more severe bleeding 1, 2
- Hematochezia with upper GI source: Suggests massive, rapid bleeding that hasn't had time to be digested 1
Diagnostic Considerations
When evaluating stool for signs of upper GI bleeding:
- Melena typically occurs when at least 50-100 mL of blood has entered the GI tract
- The black color results from the breakdown of hemoglobin by intestinal enzymes
- The tarry consistency is due to the partial digestion of blood proteins
- Melena can persist for several days after bleeding has stopped due to the transit time through the intestines
Common Causes of Upper GI Bleeding
The most common causes of upper GI bleeding that may present with melena include:
- Peptic ulcer disease (35-50%) 1, 2
- Gastroduodenal erosions (8-15%) 1, 2
- Esophagitis (5-15%) 1, 2
- Esophageal varices (5-10%) 1, 2
- Mallory-Weiss tears (15%) 1, 2
- Vascular malformations (1%) 1, 2
Clinical Pitfalls to Avoid
- Don't assume bright red rectal bleeding always indicates a lower GI source; massive upper GI bleeding can present with hematochezia 1
- Certain medications (iron, bismuth) and foods (licorice, blueberries) can cause black stools that mimic melena but aren't related to bleeding
- Melena alone doesn't definitively diagnose the source of bleeding; endoscopy is required for confirmation 1
- Upper GI bleeding ceases spontaneously in approximately 75% of cases, but this doesn't eliminate the need for proper evaluation 1