What is the evaluation and management approach for a patient presenting with melena (dark tarry stools)?

Evaluation of Dark Tarry Stools (Melena)

A patient presenting with melena requires urgent hospital evaluation with esophagogastroduodenoscopy (EGD) within 24 hours, as this represents upper gastrointestinal bleeding with significant mortality risk that is reduced by early specialist intervention. 1

Initial Assessment and Stabilization

Hemodynamic evaluation and resuscitation take priority:

• Assess vital signs immediately for signs of hemodynamic instability (tachycardia, hypotension, orthostatic changes) 1
• Establish intravenous access and initiate fluid resuscitation if needed 1
• Transfuse packed red blood cells to maintain hemoglobin above 7 g/dL (or above 9 g/dL in patients with massive bleeding or cardiovascular comorbidities) 1
• Obtain complete blood count, coagulation studies, type and cross-match 1

Confirming True Melena

Distinguish true melena from benign black stools:

• True melena has a sticky, tar-like consistency with characteristic foul odor indicating digested blood 1
• Black stools lacking this consistency typically represent dietary causes (iron supplements, bismuth, certain foods) and do not require urgent GI evaluation 1
• Obtain detailed medication and dietary history to exclude non-bleeding causes 1

Source Localization

Melena typically indicates upper GI bleeding proximal to the ligament of Treitz:

• Most common causes include peptic ulcers, gastroduodenal erosions, esophagitis, varices, and Mallory-Weiss tears 1
• In patients with obscure GI bleeding, melena doubles the odds of finding a bleeding source in the proximal small intestine 2
• Important caveat: Massive upper GI bleeding can present as bright red blood per rectum (hematochezia) if transit time is rapid 1
• Slow bleeding from the right colon can occasionally produce dark stools, though typically not true melena 1

Diagnostic Approach

EGD is the initial procedure of choice:

• Esophagogastroduodenoscopy has both diagnostic and therapeutic capabilities 1, 3
• For hemodynamically stable patients, perform early elective endoscopy ideally within 24 hours of admission 1
• In pediatric patients, the upper gastrointestinal tract is the most common bleeding source, making EGD the primary endoscopic method 4
• If EGD is negative and bleeding continues, consider small bowel capsule endoscopy, particularly in patients presenting with melena 4, 2

Risk Stratification

Identify high-risk patients requiring more aggressive management:

• Elderly patients (>65 years) have significantly higher mortality rates 1
• Patients with significant comorbidities (cardiovascular, renal, or liver disease) are at higher risk for complications 1
• Presence of vomiting, abnormal abdominal ultrasonography, or hemoglobin ≤3 g/dL below normal limit increases likelihood of finding bleeding source on EGD 4

Post-Endoscopic Management

Following successful endoscopic therapy:

• Initiate high-dose proton pump inhibitor therapy in patients with ulcer bleeding 1
• Continue monitoring hemoglobin and hemodynamic status 1
• Address underlying risk factors (NSAIDs, Helicobacter pylori, anticoagulation) 3

Common Pitfalls to Avoid

• Do not delay hospital evaluation: Early specialist intervention reduces mortality compared to delayed treatment 1
• Do not rely solely on patient descriptions: Patients use 23 different descriptors for stool color, and 22% show discrepancy between verbal description and actual color 5
• Do not assume all black stools are melena: Obtain medication history (iron, bismuth) and assess stool consistency 1
• Do not overlook small bowel sources: If EGD is negative in a patient with melena, pursue capsule endoscopy with antegrade approach 2