Melena is the presence of digested blood in the feces and makes the stools appear black and tarry. Melena is different from fresh blood in the stool (hematochezia). Melena may represent a severe, life-threatening illness, and should not be ignored. It must especially be addressed if it persists or worsens.
Melena develops when bleeding occurs into the stomach or small intestines. The bleeding must be high in the intestinal tract in order for the blood to be digested and become discolored. Bleeding into the colon or rectum (
hematochezia) appears as fresh blood in the stool.
General Causes Infectious agents
Certain drugs
Cancer
Foreign bodies in the stomach or intestines
Infiltrative and inflammatory gastrointestinal diseases
Ingestion of blood
Coagulopathies (bleeding disorders)
Metabolic and other diseases that cause gastrointestinal ulceration
Hemorrhagic gastroenteritis (HGE)
Perioperative hemorrhage (bleeding associated with surgery on the intestinal tract)
Gastrointestinal ischemia (lack of blood supply)
Ingestion of heavy metals (uncommon causes)
What to Watch For
Dark, almost black stools
Diarrhea
Vomiting
Pale gums
Other areas of bleeding or bruising on the body
Weight loss
Poor appetite
Excessive drinking or urinating
Excessive urinating
Diagnosis
A thorough history and physical examination are often helpful in determining if melena is present and in suggesting an underlying cause. To determine the exact cause, additional tests are usually necessary and include the following:
Complete blood count (CBC)
Biochemical profile
Urinalysis
Fecal examination
Abdominal and chest radiographs (X-rays)
Serology for certain infectious diseases
Coagulation profile
Abdominal ultrasonography
Upper gastrointestinal barium series
Endoscopy
