From the Guidelines
Melena is defined as the passage of black tarry stools, which occurs due to the presence of digested blood in the gastrointestinal tract. According to the guidelines for non-variceal upper gastrointestinal haemorrhage 1, melena is characterized by the vomiting of altered black blood, also known as coffee ground vomiting, and the passage of black tarry stools. This condition typically indicates bleeding from the upper GI tract (esophagus, stomach, or small intestine), as blood that originates higher in the digestive system gets broken down by digestive enzymes, turning it black 1.
The characteristic appearance of melena results from hemoglobin being converted to hematin by stomach acid and intestinal enzymes. Melena has a distinctive, foul odor and sticky consistency. It's considered a medical emergency requiring prompt evaluation, as it may indicate serious conditions like peptic ulcers, gastritis, esophageal varices, or even cancer. Blood loss can be significant—even a small amount of visible melena may represent substantial bleeding.
Some of the common causes of acute upper gastrointestinal haemorrhage include peptic ulcer, gastroduodenal erosions, oesophagitis, varices, Mallory Weiss tear, upper gastrointestinal malignancy, and vascular malformations 1. Anyone experiencing melena should seek immediate medical attention for proper diagnosis through endoscopy, imaging studies, and blood tests to identify and treat the underlying cause. The presence of melena distinguishes it from hematochezia (bright red blood in stool), which typically indicates lower GI tract bleeding. Prompt medical evaluation and treatment are essential to prevent complications and improve outcomes in patients with melena.
From the Research
Definition of Melena
- Melena is defined as tarry black stool, which is a symptom encountered in pediatric and adult clinical practice 2, 3, 4.
- It is a sign of upper gastrointestinal bleeding, which can present as melena or hematemesis, and can also present as hematochezia in cases of brisk bleeding 4.
Causes of Melena
- The bleeding source of melena can vary from the upper gastrointestinal tract to the small intestine 2.
- The most common causes of melena include duodenal ulcer, gastric ulcer, esophagitis, and esophageal varices 2.
- The upper gastrointestinal tract is the most common source of bleeding, with the small intestine being a less common source 2.
Diagnosis and Management
- Endoscopy is effective in identifying bleeding, but it does not always identify the source of bleeding 2.
- Esophagogastroduodenoscopy is the primary endoscopic method of choice for diagnosing and managing melena 2, 4.
- Small bowel capsule endoscopy may be useful in identifying the bleeding source in patients without upper gastrointestinal lesions 2.
- Risk factors that increase the propensity for recurrent bleeding should be identified and addressed 4.