Workup for Resolved Melena (Black Stool)
Even though the black stool has resolved, you should still undergo a complete blood count (CBC), stool occult blood testing, and upper endoscopy (EGD) to identify the source of bleeding and exclude serious underlying pathology that could recur. 1, 2
Essential Initial Laboratory Tests
The following blood and stool tests should be performed regardless of symptom resolution:
- Complete Blood Count (CBC) to screen for anemia from blood loss and assess for ongoing occult bleeding 1
- Stool occult blood test to detect continued microscopic bleeding even after visible melena has resolved 3
- C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) to evaluate for inflammatory processes that could cause GI bleeding 1
- Serum chemistries and albumin if there are concerns about chronic disease or malabsorption 3
Endoscopic Evaluation
Upper endoscopy (esophagogastroduodenoscopy/EGD) is the primary examination of choice because the upper gastrointestinal tract is the most common source of melena:
- EGD should be performed to identify the bleeding source, as duodenal ulcer, gastric ulcer, esophagitis, and esophageal varices are the most common causes of melena 2
- The upper GI tract accounts for the vast majority of melena cases in both children and adults 2
- If EGD is nondiagnostic, colonoscopy should be considered, though the diagnostic yield is relatively low (4.8%) for identifying bleeding sources after negative EGD 4
Additional Testing Based on Clinical Context
Consider these tests if specific risk factors or symptoms are present:
- Small bowel capsule endoscopy may be useful if both EGD and colonoscopy are negative, as the small intestine can be a bleeding source in approximately 13% of melena cases 2
- Stool culture for bacterial pathogens (Salmonella, Shigella, Campylobacter) if there is associated diarrhea, fever, or recent travel 1
- Clostridium difficile testing if there is recent antibiotic use or hospitalization 1
Critical Pitfalls to Avoid
Do not assume that resolved symptoms mean no workup is needed. The underlying cause of melena (such as peptic ulcer disease, vascular malformations, or even malignancy) may still be present and can cause life-threatening rebleeding 2, 4. The fact that colonoscopy identifies colon tumors more frequently in patients with melena (OR 2.87) emphasizes the importance of complete evaluation even after symptom resolution 4.
Urgent evaluation is warranted if you have alarm features including significant weight loss, fever, continued or recurrent bleeding, severe anemia (hemoglobin ≥3 g/dL below normal), vomiting, or abnormal physical findings 1, 2.