Gastroenterology & Internal Medicine & Emergency Medicine & Family Medicine
Melena (blood in stools)
Melena is defined as the passage of black, tarry, foul-smelling, and sticky stools (resembling «pitch tar») resulting from the breakdown of blood in the digestive tract by digestive enzymes and intestinal bacteria—hemoglobin is converted into black hemosiderin (iron sulfide). It typically indicates upper gastrointestinal bleeding (UGIB)—originating from the esophagus, stomach, or duodenum (upstream of the ligament of Treitz)—where at least 50–100 mL of blood has remained long enough to be broken down. Melena must be distinguished from rectal bleeding (bright red blood in the stool—a sign of lower gastrointestinal bleeding in most cases), hematemesis (vomiting of red blood or coffee-ground-like material—UGB), and non-melena black stools (intake of iron + bismuth + charcoal + spinach + licorice). The most common cause of melena is peptic ulcer disease (50–60% of cases of upper gastrointestinal bleeding), followed by esophagitis + esophageal varices (portal hypertension + cirrhosis) + Mallory-Weiss syndrome + angiodysplasias + gastric cancers. Melena constitutes a medical emergency—mortality in severe cases remains 3–10% in developed countries despite therapeutic advances. Assessment of severity (Glasgow-Blatchford score or Rockall score) guides the decision to hospitalize and the timing of endoscopy. High-dose IV proton pump inhibitor (PPI) is initiated immediately, and endoscopy is performed within 24 hours (or within 6–12 hours if hemodynamic instability is present).
Pathophysiology, etiologies, and clinical evaluation
- Mechanism of Melena and Classification of Gastrointestinal Bleeding: Mechanism of melena formation: blood from an upper gastrointestinal (GI) bleed (above the ligament of Treitz – duodenojejunal junction) → blood in contact with gastric acids + digestive enzymes + intestinal bacteria → hemoglobin breakdown → conversion to hemosiderin (iron sulfide) → black, tarry, foul-smelling stools → minimal volume: 50–100 mL of blood in the stomach + sufficiently slow transit (>8h) → an abundant upper GI bleed with rapid transit can cause hematochezia (bright red blood) and not melena + melena vs. hematochezia vs. hematemesis: melena: black, tarry stools → upper GI bleed (esophagus + stomach + duodenum) → or proximal small bowel bleed (rare) + hematochezia: bright red blood at the anal level or mixed with stool → lower GI bleed (colon + rectum + anus) → but if upper GI bleed is very abundant → can cause hematochezia + hematemesis: vomiting bright red blood (active bleeding) + or coffee-ground appearance (digested blood = slower bleeding) → upper GI bleed + severity classification: minor hemorrhage: hemodynamically stable + Hb >100 g/L + no signs of hypovolemia → moderate hemorrhage: mild tachycardia + Hb 70–100 g/L → severe hemorrhage: hemodynamic instability (tachycardia >100 bpm + hypotension) <90 mmHg) + Hb <70 g/L → urgent transfusion + ICU management → Glasgow-Blatchford score (GBS): 0 = very low risk (discharge possible) → ≥1 = hospitalization + endoscopy → parameters: blood urea + hemoglobin + systolic BP + HR + presence of melena + syncope + liver disease + heart failure → excellent triage tool
- Etiologies of upper gastrointestinal bleeding and risk factors: Main causes of melena by frequency: gastroduodenal ulcer (GDU): 50–60% of cases of melena → duodenal ulcer (50–60% of GDUs) + gastric ulcer (30–40% of cases) → causes: H. pylori (80% of duodenal ulcers) + NSAIDs + aspirin + stress (Curling’s ulcer + Cushing’s syndrome) → site of bleeding: posterior wall of the duodenal bulb (gastroduodenal artery) → potentially massive hemorrhage → acute gastric mucosal lesions (AGML): stress + sepsis + burns + NSAIDs + alcohol → + esophageal/gastric varices (portal hypertension — alcoholic cirrhosis + HBV + HCV): 10–20% of HDH → mortality 20–30% per episode → high risk of recurrence → Mallory-Weiss syndrome: longitudinal tear of the gastroesophageal junction following repeated vomiting → 5–10% of HDH → generally self-limiting + severe esophagitis + stomach cancer (10% of HDH) + gastric and duodenal angiodysplasias (especially in the elderly + IR + aortic stenosis — Heyde syndrome) + aorto-enteric fistula (late complication of aortic prosthetic surgery): melena + sentinel sign → surgical emergency → risk factors for severe HDH: advanced age + use of NSAIDs + anticoagulants + antiplatelet agents + aspirin + cirrhosis + alcoholism + chronic kidney disease (CKD) + history of upper gastrointestinal bleeding (UGD) + Helicobacter pylori + corticosteroids + SSRIs (increase the risk of GI bleeding)
Support and treatment according to etiology
| Appearance / treatment | Data, protocols and results | Key studies and recommendations |
|---|---|---|
| Initial stabilization and urgent gastroscopy Hemodynamic resuscitation — 2 large IV lines — Lactated Ringer's NaCl — RBC transfusion threshold Hb 70-80 — IV PPI bolus infusion — gastroscopy 24h — instability 6-12h — Glasgow-Blatchford — Rockall — endoscopic hemostasis — clips — epinephrine injection — thermal coagulation |
Initial management of melena with upper gastrointestinal bleeding: immediate hemodynamic assessment: BP + HR + oxygen saturation + level of consciousness → if unstable (HR >100 + systolic BP <90 mmHg) → call 911 + immediate resuscitation → vascular access: 2 large-bore IV lines (16 G minimum) → fluid resuscitation: 0.9% NaCl 1L over 3 hours or Ringer’s lactate 500 mL as rapid IV → goal: SBP ≥90 mmHg + HR <100 bpm → red blood cell transfusion: liberal threshold → Hb <70 g/L in healthy subjects → Hb <80 g/L in patients with coronary artery disease + the elderly → Villanueva 2013 — NEJM (TRIGGER trial n=921): restrictive strategy (transfusion if Hb <70) vs. liberal strategy (Hb <90) → restrictive strategy associated with better survival (95 % vs. 91 %) and fewer bleeding recurrences → high-dose IV PPI: omeprazole 80 mg IV bolus → then continuous infusion 8 mg/h × 72 h → mechanism: increased gastric pH → clot stabilization (the clot lyses at pH <5 → PPIs maintain pH >6) → Leontiadis 2007 — Cochrane: PPI + acute peptic ulcer → reduced risk of recurrence + surgery → urgent endoscopy: within 24 hours for most patients + within 6–12 hours if: persistent hemodynamic instability + or profuse hematemesis + or cirrhosis with suspected varices → endoscopy allows for: etiological diagnosis + ulcer classification (Forrest criteria) + endoscopic hemostasis if active bleeding or high risk of recurrence → Forrest criteria: Ia (active arterial jet) + Ib (active oozing) + IIa (visible non-bleeding vessel) + IIb (adherent clot) → mandatory hemostasis → IIc (pigmented black spot) + III (clean base) → low risk + no hemostasis → endoscopic hemostasis: adrenaline injection (1:10,000) + thermocoagulation (hot probe + argon plasma coagulation) + or placement of hemostatic clips → adrenaline injection alone is insufficient → always combine with a second mechanical or thermal method → Cochrane meta-analyses: combined hemostasis is superior | Villanueva 2013 — NEJM (TRIGGER trial n=921): Restrictive vs. liberal transfusion + IVIG → restrictive strategy superior → reference + Leontiadis 2007 — Cochrane: PPI + ulcerative GI bleeding → reduced recurrence + surgery → reference + Laine 2012 — NEJM: Gastroscopy + endoscopic hemostasis + IVIG → review + Barkun 2019 — Annals of Internal Medicine (ESGE + BSG guidelines): High-dose IVIG → stabilization + PPI + endoscopy → INESSS Québec + RAMQ: IV PPI + gastroscopy → reimbursed + digestive emergencies in Quebec → gastroenterologist on call |
| Hemorrhagic gastroduodenal ulcer and esophageal varices Forrest Ia, Ib, IIa, IIb - endoscopic hemostasis - oral PPI after 72h - H. pylori eradication - NSAIDs stop - varices elastic band ligation - terlipressin octreotide - TIPS - propranolol secondary prevention - Sengstaken-Blakemore tube - variceal mortality |
Hemorrhagic peptic ulcer — specific treatment: after endoscopic hemostasis + IV PPI for 72 hours → switch to high-dose oral PPI: omeprazole 40 mg twice daily for 2–4 weeks → then standard dose → H. pylori eradication: mandatory if H. pylori is positive → triple therapy or quadruple therapy depending on local resistance patterns (see H. pylori fact sheet) → eradication verified by urea breath test 4 weeks after treatment → discontinue NSAIDs/aspirin if possible → if NSAIDs are necessary → add continuous PPI therapy → cirrhosis + enhanced gastroprotection → hemostatic surgery (hemostatic gastrectomy): if 2 attempts at endoscopic hemostasis fail → or massive bleeding inaccessible to endoscopy → interventional angiography (embolization): alternative to surgery if patient is at high surgical risk + esophageal variceal bleeding (portal hypertension): the most serious hemorrhagic complication of cirrhosis → mortality 20–30% per episode → acute treatment of bleeding varices: terlipressin (Glypressin) 2 mg IV × 4/day × 5 days: splanchnic vasoconstrictor → reduces portal pressure → or octreotide (Sandostatin) 50 µg IV bolus → followed by infusion at 50 µg/h × 5 days → initiated AS SOON AS THE DIAGNOSIS IS SUSPECTED → even before endoscopy → systematic antibiotic prophylaxis: ceftriaxone 1 g IV × 1/day × 7 days → reduces the risk of infection + improves survival (Fernandez 2006 — Gastroenterology) → endoscopic elastic band ligation (EBL): standard endoscopic treatment for varices → superior to sclerotherapy → Villanueva 2019 NEJM + Sengstaken-Blakemore balloon: if massive uncontrolled bleeding → temporary hemostasis → bridge to TIPS or re-endoscopy + TIPS (Transjugular Intrahepatic Portosystemic Shunt): if second endoscopic attempts fail or uncontrollable bleeding → portosystemic shunt → Garcia-Tsao 2017 — Hepatology (AASLD): Early TIPS (within 72 hours) in patients with Child-Pugh B or C cirrhosis → improves survival → secondary prevention of varices: propranolol 20–80 mg × 2/day or carvedilol → to reduce portal pressure + repeat LEB sessions every 2–4 weeks until complete obliteration | Fernandez 2006 — Gastroenterology: antibiotic prophylaxis + varices + survival → reference + Garcia-Tsao 2017 — Hepatology (AASLD guidelines): varices + early TIPS + treatment → Villanueva 2019 — NEJM: EMB + varices + treatment + Barkun 2019 — Annals of Internal Medicine (ESGE + BSG guidelines): high-dose HDH → treatment + follow-up + Laine 2012 — NEJM: endoscopic hemostasis + ulcer + Cochrane + Leontiadis 2007 — Cochrane: PPI + ulcer recurrence + INESSS Quebec + RAMQ: oral PPI + terlipressin + octreotide + antibiotic prophylaxis → reimbursed for indications + interventional gastroenterology Quebec: CHUM + MUHC + CHQ |
| Differential diagnosis, workup, and follow-up after heart-lung transplant Black, non-melenic stools, bismuth, iron — rectorrhagia vs. melena — CBC, reticulocytes — BUN, creatinine — coagulation, INR — blood type — Fecal Occult Blood test — aortoenteric fistula — oral PPI as a bridge — H. pylori eradication check — NSAID restart — antiplatelet resumption |
Differential diagnosis of melena and initial biological assessment: non-melena black stools: oral iron (very frequent - very black + dry stools) + bismuth subsalicylate (Pepto-Bismol) + activated charcoal + licorice + large amounts of spinach → non-melena odor → guaiac test (Hemoccult) negative (does not detect non-hemoglobin pigments) → vs true melena: guaiac test positive + characteristic odor + tarry texture → hematochezia vs melena: bright red blood = lower GI bleeding (colon + rectum + anus) in the majority → but very heavy upper GI bleeding (UGIB) can cause hematochezia (red blood) → if hemodynamically unstable patient + hematochezia → always look for UGIB → obligatory rectal exam + CBC can indicate high UGIB with low Hb + biological assessment for any suspected UGIB: CBC + reticulocytes (acute bleeding = normocytic anemia + reticulocytes not yet elevated in the first hours) + creatinine + BUN (elevated BUN/creatinine ratio if UGIB - prerenal azotemia from absorption of blood proteins in the intestine) + electrolytes + coagulation panel (PT + PTT + INR - if cirrhosis or anticoagulants) + blood type + antibody screen (crossmatch) → infectious workup if fever + alcohol breath test if intoxication → follow-up after ulcerative UGIB: H. pylori eradication x 4 weeks + follow-up test (urea breath test or fecal antigen test) → resume NSAIDs: if necessary → PPI continuous + evaluate the actual indication for NSAIDs → resume antiplatelets (aspirin + clopidogrel): early resumption if high cardiovascular risk (after confirmed endoscopic hemostasis) → Sung 2010 - Annals of Internal Medicine: early resumption of aspirin after hemostasis vs discontinuation → lower overall mortality with early resumption → follow-up gastroscopy: not systematic if Forrest IIc or IIc+ or if hemostasis confirmed → systematic if Forrest IIa/IIb or after varix hemostasis | Villanueva 2013 — NEJM (TRIGGER): transfusion strategy + Barkun 2019 — Annals of Internal Medicine: H. pylori high dose → guidelines → post-hemorrhage follow-up + Sung 2010 — Annals of Internal Medicine: aspirin resumption after hemostasis + H. pylori + Leontiadis 2007 — Cochrane: PPI + ulcer → reference + Laine 2012 — NEJM: endoscopic hemostasis + follow-up + INESSS Quebec + RAMQ: oral PPI + H. pylori breath test + follow-up gastroscopy → reimbursed within indications + Gastroenterology Quebec: MUHC + CHUM + H. pylori protocols |
ℹ️
Melena is a medical emergency—any black, tarry, foul-smelling stool requires immediate evaluation to rule out upper gastrointestinal bleeding: The Glasgow-Blatchford score guides the decision for hospitalization. High-dose IV PPI (omeprazole 80 mg bolus + 8 mg/h) should be started immediately. Gastroscopy should be performed within 24 hours (or within 6–12 hours if hemodynamically unstable). In a cirrhotic patient, start terlipressin or octreotide AND antibiotic prophylaxis (ceftriaxone) even before gastroscopy. Never confuse black stools due to iron or bismuth intake with true melena.
Situations requiring a 911 call or immediate emergency care
Black tarry stools + tachycardia (>100 bpm) + hypotension (SBP <90 mmHg) + lightheadedness + pallor + cold sweats → Upper gastrointestinal bleeding with hemorrhagic shock → Call 911 → 2 large-bore IV lines → 0.9% NaCl fluid resuscitation (1L over 3 hours) → Red blood cell transfusion if Hb <70 g/L → IPP IV 80 mg bolus → gastroscopy within 6 hours.
Cirrhotic patient + melena or hematemesis + abundant rectorrhagia + tachycardia Esophageal variceal rupture until proven otherwise → call 911 → terlipressin 2 mg IV or octreotide 50 mcg IV bolus → ceftriaxone 1 g IV → urgent gastroscopy within 6–12h → if uncontrollable bleeding → Sengstaken-Blakemore tube + TIPS.
History of prosthetic aortic surgery (aortobifemoral bypass + aortic endoprosthesis) + melena + or low-volume hematemesis (sentinel melena) + back or abdominal pain Aortoenteric fistula → Absolute surgical emergency → Call 911 → Emergency aortic CT angiography → Vascular surgery → DO NOT perform gastroscopy as a first-line treatment if aortoenteric fistula is suspected (risk of sudden decompression).
Consult at Clinique Omicron
Clinique Omicron physicians evaluate any patient presenting with black stools to differentiate true melena from non-melenic black stools (iron + bismuth). They apply the Glasgow-Blatchford score to decide on hospitalization, initiate high-dose PPIs, prescribe urgent gastroscopy, immediately refer unstable patients to the emergency room, ensure post-discharge follow-up (H. pylori eradication + oral PPI + coagulation assessment), and coordinate with the gastroenterologist. Consultations are available at several service points in Quebec and via telemedicine. To make an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not substitute for medical advice from a physician or gastroenterologist. Any melena with hemodynamic instability is a life-threatening emergency — call 911 immediately.
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