Black Tarry Stools (Melena): Evaluation and Management
Patients presenting with black, tarry stools require immediate risk stratification using validated prognostic scales (Blatchford or Rockall score), followed by urgent upper endoscopy within 24 hours after appropriate resuscitation, as melena indicates upper gastrointestinal bleeding with significant mortality risk (11% in-hospital, 33% if bleeding develops during hospitalization). 1
Initial Assessment and Risk Stratification
Immediate Clinical Evaluation
Black, tarry stools (melena) represent upper gastrointestinal bleeding from digested blood 1. Key clinical predictors of high-risk bleeding include:
- Age >65 years
- Hemodynamic instability (pulse >100 bpm, systolic BP <100 mmHg)
- Hemoglobin <8 g/dL
- Fresh hematemesis (patients with both hematemesis and melena have more severe bleeding than melena alone) 1
- Elevated BUN:creatinine ratio >30 (LR 7.5 for upper GI source) 2
- Comorbidities (cardiac, hepatic, renal disease)
- Anticoagulation or antiplatelet use
Risk Stratification Tools
Use the Blatchford score first - it accurately identifies low-risk patients who can be managed as outpatients without urgent endoscopy 3. The score incorporates:
- Hemoglobin level
- Blood urea level
- Pulse and systolic blood pressure
- Presence of syncope or melena
- Evidence of hepatic or cardiac disease
A Blatchford score of 0 has an LR of 0.02 for requiring urgent intervention - these patients do not need immediate hospitalization 2.
For hospitalized patients, apply the Rockall score (pre-endoscopy version initially, then complete score post-endoscopy) to predict rebleeding and mortality 3.
Resuscitation and Pre-Endoscopy Management
Immediate Actions
- Establish IV access (two large-bore lines if hemodynamically unstable)
- Transfuse if hemoglobin <8 g/dL or signs of shock 3
- Admit under gastroenterology service with surgical consultation available 1
- NPO status until endoscopy completed
- Nasogastric lavage with blood or coffee grounds increases likelihood of upper GI source (LR 9.6) 2
Critical pitfall: Blood clots in stool (LR 0.05) make upper GI bleeding much less likely - consider lower GI source 2.
Endoscopic Evaluation
Timing and Approach
Perform upper endoscopy within 24 hours for all patients with melena and positive risk stratification 1. Earlier endoscopy (within 12 hours) for:
- Hemodynamic instability despite resuscitation
- Active hematemesis
- High-risk Rockall or Blatchford scores
Expected Findings
A source is identified in approximately 80% of cases 1:
- Peptic ulcer: 35-50% (most common)
- Gastroduodenal erosions: 8-15%
- Esophagitis: 5-15%
- Varices: 5-10%
- Mallory-Weiss tear: 15%
High-risk endoscopic stigmata requiring intervention:
- Active arterial bleeding
- Non-bleeding visible vessel
- Adherent clot
- Ulcer >2 cm
- Posterior duodenal or lesser curve gastric location
Post-Endoscopy Management
Pharmacologic Therapy
For bleeding peptic ulcers after successful endoscopic therapy, administer high-dose PPI: omeprazole 80 mg IV bolus followed by 8 mg/hour continuous infusion for 72 hours 1. This applies to all ulcer locations (duodenal, gastric, stomal).
Monitoring
- Continuous observation of vital signs, urine output for 4-6 hours post-endoscopy
- Allow oral intake if hemodynamically stable 4-6 hours post-procedure 1
- Rebleeding indicators: fresh melena/hematemesis, BP drop, pulse rise, hemoglobin fall >20 g/L over 24 hours 1
Management of Rebleeding
If rebleeding occurs, perform repeat endoscopy to confirm and attempt repeat endoscopic therapy once 1. This approach has equivalent or better outcomes than immediate surgery.
Indications for urgent surgery (without repeat endoscopy):
- Uncontrolled bleeding despite endoscopic therapy
- Second rebleed after repeat endoscopic intervention
- Giant posterior duodenal ulcer with multiple bleeding points in elderly patient with comorbidities
When Upper Endoscopy is Non-Diagnostic
If upper endoscopy is negative (occurs in 24% of melena cases), proceed with colonoscopy 4, 5. The right colon is the most likely source when upper endoscopy is non-diagnostic:
- Colonoscopy identifies source in 37% of cases with non-diagnostic EGD 4
- Right-sided arteriovenous malformations, colitis, large polyps (≥20 mm), tumors, or ulcers are typical findings 5
- Diagnostic yield: 4.8% for suspected bleeding source 5
Melena in obscure GI bleeding doubles the odds (OR 1.97) of finding a bleeding site in the proximal small intestine - if capsule endoscopy or deep enteroscopy is needed, begin with antegrade approach 6.
Avoid: Small bowel contrast studies, flexible sigmoidoscopy alone, barium enema alone, or angiography as initial tests - these have poor yield 4.
Key Clinical Pearls
- Melena alone indicates less severe bleeding than melena plus hematemesis 1
- Mortality is lower in specialist gastroenterology units due to protocol adherence 1
- Combined medical-surgical care is essential for critically ill patients 1
- Tachycardia (LR 4.9) and hemoglobin <8 g/dL (LR 4.5-6.2) strongly predict severe bleeding requiring urgent intervention 2