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Melena

What Is It, Causes, Symptoms, Bleeding, Treatment, and More

Author: Jennifer Cheung, RN

Editors: Antonella Melani, MD, Lisa Miklush, PhD, RN, CNS, Ahaana Singh

Illustrator: Jillian Dunbar

What is melena?

Melena refers to black stools that occur as a result of gastrointestinal bleeding. This bleeding typically originates from the upper gastrointestinal (GI) tract, which includes the mouth, esophagus, stomach, and the first part of the small intestine. In some cases, bleeding in the ascending colon of the large intestine, which is located in the lower GI tract, can also result in melena.

Melena should not be confused with hematochezia, which refers to fresh blood in the stools that leads to maroon or red-colored stools. This blood typically comes from the lower GI tract, most often from rectal bleeding, such as hemorrhoids.

What causes melena?

Melena often results from damage to the upper GI tract lining, swollen blood vessels, or bleeding disorders.

• Peptic ulcer disease, which is characterized by painful ulcers or sores that develop in the stomach or small intestine, can result in melena. Peptic ulcer disease can be caused by:

  • Heliobacter pylori (H. pylori) infection 

  • Chronic use of aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs). 

• Damage to the GI tract

  • Mallory–Weiss tears (tears or lacerations and consequent bleeding in the lower esophagus typically caused by excessive vomiting) 

  • Excessive acid production

    • Gastroesophageal reflux disease (GERD) may cause severe inflammation of the esophagus known as erosive esophagitis, which in turn can lead to ulceration and consequent bleeding. 

  • Tumor development, including adenocarcinomas, squamous cell carcinomas, carcinoid tumors, and lipomas.

• Swollen blood vessels, or varices, can also lead to upper GI bleeding. 

  • This most commonly occurs with portal hypertension, which refers to increased blood pressure in the portal vein.

    • Liver disease such as cirrhosis, or liver scarring, can cause the blockage of blood flow through the liver, thus causing blood to back up in the portal vein, which then leads to increased pressure or portal hypertension. 

• Blood disorders that are characterized by excessive bleeding and frequent bruising:

  • Hemophilia

  • Thrombocytopenia

What symptoms are associated with melena?

Melena appears as black, tar-like, sticky stools. The black color is caused by enzymes breaking down and digesting the blood as it moves through the GI tract. This color is often accompanied by a strong, foul odor. 

Associated symptoms that may be seen with melena vary depending on the amount of blood loss and the source of bleeding. 

• Significant blood loss 

  • Low blood volume

  • Anemia

  • Shock (weakness, shortness of breath, pale skin, clamminess, dizziness, confusion, and tachycardia or a fast heart rate) 

• Mild blood loss 

  • Symptoms associated with the source of bleeding. 

    • Bleeding in the small intestine:

      • Abdominal pain 

    • Bleeding from the mouth, esophagus, or stomach: 

      • Painful swallowing

      • Indigestion

      • Vomiting blood (i.e., hematemesis)

How do you diagnose melena?

Diagnosis begins by identifying the sources of bleeding in order to determine and treat the underlying cause. 

• Clinical evaluation

  • Medical history review 

    • Identify related causes, such as chronic NSAID use. 

• Procedural diagnosis

  • Nasogastric lavage (also known as the pumping of stomach contents) can be used to determine the severity of blood loss. 

  • Upper endoscopy (a minimally invasive procedure used to look inside the body) will often be performed to determine the exact source of bleeding.

How do you treat melena?

• Medications 

  • Proton pump inhibitors (e.g., esomeprazole or pantoprazole) can help reduce acid production, which encourages the healing of peptic ulcers and thus reduces the risk of recurrent bleeding. 

  • Proton pump inhibitors, along with antibiotics, can also be used to treat H. Pylori infection, which is another potential cause of melena. 

• Procedures

  • If necessary, the bleeding can be controlled through a combination of endoscopic therapies. 

    • Injection therapy involves the injection of medication directly into the source of bleeding to encourage coagulation (blood clotting). 

    • Thermal techniques apply heat probes to cauterize the bleeding. 

    • Mechanical techniques apply pressure, using devices like clips or rubber band ligation.

  • Angiographic embolization may be performed, in which medication or coils are placed onto a guided catheter to block blood flow at the location of bleeding. 

  • Surgical therapies can also be used to stitch up ulcers or lacerations. 

  • Severe cases may need blood transfusions.

Frequently Asked Questions

Is melena a sign of active bleeding?

If melena is accompanied by symptoms of shock, it can be a sign of active bleeding. In such cases, it is considered a medical emergency and it is important to seek medical attention immediately. On the other hand, cases with no apparent symptoms of shock should seek medical attention if the melena continues beyond 5 to 7 days. 

How long does melena last?

Depending on the amount of blood loss and the individual’s gastrointestinal motility, melena may continue up to 5 days after the bleeding has stopped.

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