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 does melena look like?

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. 

What causes melena?

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

The most common cause of melena is peptic ulcer disease, in which painful ulcers or sores develop in the stomach or small intestine. This can be caused by an infection of Heliobacter pylori (H. pylori), which causes inflammation of the stomach known as gastritis, leading to high acid secretion that damages the mucosa and can lead to ulcer development. Similarly, chronic use of aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) can also lead to gastritis and resultant ulcers of the GI tract. 

Damage to the GI tract can result from various other conditions, such as Mallory–Weiss tears, which refers to tears or lacerations and consequent bleeding in the lower esophagus typically caused by excessive vomiting. Additionally, conditions associated with excessive acid production, such as 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. In some cases, GI bleeding can also be indicative of 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. The increase in pressure can cause esophageal and gastric varices, which are fragile and bleed easily.

Blood disorders that are characterized by excessive bleeding and frequent bruising, such as hemophilia and thrombocytopenia, can also contribute to bleeding in the GI tract.

What symptoms are associated with melena?

Symptoms that may be seen with melena vary depending on the amount of blood loss and the source of bleeding. Significant blood loss can lead to symptoms of low blood volume, anemia, or shock, such as weakness, shortness of breath, pale skin, clamminess, dizziness, confusion, and tachycardia or a fast heart rate. 

Individuals with mild blood loss often only experience symptoms associated with the source of bleeding. If bleeding occurs in the small intestine, individuals may experience abdominal pain. Bleeding from the mouth, esophagus, or stomach often results in painful swallowing, indigestion, or vomiting blood (also referred to as hematemesis).

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 do you treat melena?

Diagnosis or treatment begins by identifying the sources of bleeding in order to determine and treat the underlying cause. An assessment of the individual’s medical history is performed to identify related causes, such as chronic NSAID use. A nasogastric lavage (also known as the pumping of stomach contents) can be used to determine the severity of blood loss and to prepare the GI tract for endoscopy, which is a minimally invasive procedure used to look inside the body. An upper endoscopy will often be performed to determine the exact source of bleeding.

Medication therapy with proton pump inhibitors, such as 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. 

If necessary, the bleeding can be controlled through a combination of endoscopic therapies. The most commonly performed endoscopic therapy is injection therapy, in which medication is injected directly into the source of bleeding to encourage coagulation (blood clotting). It is often combined with other endoscopic therapies, such as thermal techniques that apply heat probes to cauterize the bleeding, or mechanical techniques that apply pressure, using devices like clips or rubber band ligation.

In some cases, 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. Finally, severe cases may need blood transfusions.

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.

What are the most important facts to know about melena?

Melena refers to black, tar-like, sticky stools and usually results from upper gastrointestinal bleeding. The source of bleeding can come from damage to the lining of the GI tract, breakage of swollen blood vessels, or other conditions that prolong bleeding such as hemophilia. Symptoms typically depend on the amount of blood lost and the source of bleeding. Significant blood loss is a medical emergency and can cause symptoms of low blood volume, anemia, or shock, such as weakness, shortness of breath, pale skin, dizziness, and tachycardia. In cases of mild blood loss, symptoms are usually associated with the source of bleeding and can include abdominal pain, painful swallowing, indigestion, or vomiting blood. Treatment involves finding and treating the underlying cause. If necessary, the bleeding can be controlled through a combination of endoscopic therapies that inject medications to encourage coagulation, apply heat probes to cauterize the bleeding, and apply pressure using devices like clips or rubber band ligation. Finally, severe cases may need blood transfusions.