What is the appropriate diagnosis and treatment for melena (black stool)?

Black Stool (Melena): Diagnosis and Management

Immediate Assessment and Stabilization

All patients presenting with melena require urgent hemodynamic assessment and hospital evaluation, as mortality rates are significant and early specialist intervention reduces death compared to delayed treatment. 1

Initial Resuscitation Priority

• Establish two large-bore IV lines immediately and begin aggressive fluid resuscitation with normal saline while simultaneously assessing hemodynamic stability—this takes absolute priority before any diagnostic procedures. 1
• Check pulse and blood pressure: patients with pulse >100 bpm and systolic BP <100 mmHg represent severe bleeding requiring intensive monitoring. 1
• Transfuse packed red blood cells to maintain hemoglobin >7 g/dL in most patients, or >9 g/dL in those with massive bleeding or cardiovascular comorbidities. 2, 1, 3
• Insert urinary catheter and monitor hourly urine output (target >30 ml/h indicates adequate resuscitation). 1
• If shock persists after 2 liters of saline, add plasma expanders as this indicates ≥20% blood volume loss. 1

Critical Pitfall to Avoid

• Never perform endoscopy before achieving adequate resuscitation—this is a critical error that increases mortality. 1

Diagnostic Workup

Laboratory Evaluation

• Obtain complete blood count to assess for anemia in all patients with stool color changes. 2
• Check blood urea nitrogen (BUN) and BUN/creatinine ratio, as these predict need for endoscopic intervention. 4
• Perform stool hemoccult testing if bleeding is suspected. 2

Endoscopic Evaluation

• Esophagogastroduodenoscopy (EGD) is the initial procedure of choice as it has both diagnostic and therapeutic capabilities. 1, 3
• All patients with melena require sigmoidoscopy at minimum. 2
• For hemodynamically stable patients, perform early elective endoscopy ideally within 24 hours of admission. 1, 3
• For unstable patients or those with ongoing bleeding, perform emergency endoscopy within 24 hours. 3
• In severely bleeding patients, consider endotracheal intubation before endoscopy to prevent pulmonary aspiration. 1

Nasogastric Tube Placement

• Insert nasogastric tube to assess for upper GI source of bleeding. 2

Common Causes to Identify

The most common sources of melena include:

• Peptic ulcers (most common, especially duodenal ulcers). 1, 5
• Gastroduodenal erosions. 1
• Esophagitis. 1, 5
• Esophageal varices. 1, 5
• Mallory-Weiss tears. 1

The upper gastrointestinal tract is the most common bleeding source in both adults and children. 5

Therapeutic Interventions

Endoscopic Therapy

• During EGD, apply appropriate endoscopic therapy if active bleeding, non-bleeding visible vessel, or adherent clot is found. 3
• Available treatments include injection therapy, mechanical therapy (endoscopic clips), or ablative therapy (argon plasma coagulation). 3

Post-Endoscopy Medical Management

• Following successful endoscopic therapy in patients with ulcer bleeding, administer high-dose proton pump inhibitor therapy (80 mg omeprazole stat followed by infusion of 8 mg hourly for 72 hours). 1, 3
• Address underlying causes: Helicobacter pylori eradication, acid suppression, and counsel regarding NSAID use. 1

Refractory Bleeding

• If endoscopic therapy is unsuccessful or bleeding recurs, consider angiographic embolization techniques. 3
• External beam radiation therapy can effectively manage both acute and chronic gastrointestinal bleeding when endoscopic and interventional approaches fail. 3

Further Evaluation if Upper Endoscopy Negative

• Proceed to colonoscopy if upper endoscopy is negative, as the bleeding source may be colonic. 2
• Consider small bowel capsule endoscopy in patients without upper gastrointestinal lesions, as the small intestine can be the bleeding source. 5

Special Populations Requiring Aggressive Management

• Elderly patients (>65 years) have significantly higher mortality rates and require more aggressive management. 3
• Patients with significant comorbidities (especially cardiovascular, renal, or liver disease) are at higher risk for complications. 1, 3
• Specifically assess for cirrhosis as these patients require specialized management and have significantly higher mortality. 1

Important Distinction: True Melena vs. Simple Black Stools

• Black stools that lack the sticky, tar-like consistency and characteristic odor of melena typically do not represent digested blood and generally do not require urgent GI evaluation unless other concerning features are present. 1
• Obtain detailed medication and dietary history (iron supplements, bismuth, activated charcoal, certain foods) to identify non-bleeding causes when simple black stools are present. 1