The key difference between hematochezia and melena is that hematochezia is the passing of red colour fresh blood with stool, while melena is the passing of black, tarry, and sticky stools due to upper gastrointestinal bleeding.
Gastrointestinal bleeding occurs when there is a problem or a disease in your gastrointestinal tract. As a result, stool may be released with blood, or you may vomit blood. Your stool may also appear black. This bleeding can be a mild, severe, or life-threatening situation. Hence, prompt medical treatment is essential. Bleeding can occur from any site of the GI tract, such as esophagus, stomach, small intestine, large intestine or colon, rectum, and anus. Therefore, the treatments depend on the origin/source of the bleeding. Endoscopy is the most common test used to detect GI bleeding. Melena and hematochezia are two symptoms of GI bleeding. Melena occurs mainly due to upper GI bleeding, while hematochezia occurs mainly due to lower GI bleeding.
What is Hematochezia?
Hematochezia is a symptom of lower gastrointestinal bleeding, especially due to colon bleeding. In hematochezia, fresh blood can be seen in or with stools. Blood can come out mixed with stools or separately. Bright-coloured fresh blood is due to the blood travelling a small distance, unlike in melena. Causes for hematochezia can be cancers, neoplastic polyps, inflammatory conditions, ischemic colitis, and hemorrhoids. Anal fissures and anorectal stricture can also cause hematochezia. Together with hematochezia, symptoms such as diarrhea, changes in bowel habits, abdominal pain, and systemic symptoms such as fever and weight loss can be observed during the lower GI tract bleeding. In neonates, hematochezia can be due to blood swallowed at birth. Necrotizing enterocolitis and midgut volvulus are the other serious causes of hematochezia in a neonate.
What is Melena?
Melena is a condition in which black colour, sticky, tar-like stools is released from the anus due to upper gastrointestinal bleeding/hemorrhage. The upper gastrointestinal tract includes the mouth, esophagus, stomach, and the first part of the small intestine. Therefore, the digested blood released during the melena is mainly originated from the upper gastrointestinal tract. The black colour is due to the digestion of blood by the enzymes when going through the GI tract.
Upper gastrointestinal bleeding can occur due to damage to the upper GI tract lining, swollen blood vessels, and blood disorders such as hemophilia and thrombocytopenia. Some of the main symptoms of melena are abdominal pain, painful swallowing, indigestion, and vomiting blood. Melena can become a medical emergency if a significant amount of blood is lost.
What are the Similarities Between Hematochezia and Melena?
- Hematochezia and melena are two of the several symptoms of acute gastrointestinal bleeding.
- In both cases, blood is released with stools.
- They can be mild, severe, or life-threatening conditions.
- Endoscopy is the most common test for both conditions.
What is the Difference Between Hematochezia and Melena?
The key difference between hematochezia and melena is that hematochezia refers to the release of fresh blood in or with stool, while melena refers to the release of black, sticky, and tarry stools. Due to hematochezia, stools appear as maroon or red coloured, while due to melena, stools appear as black coloured. Moreover, blood originates from the lower GI tract in hematochezia, while blood originates from the upper GI tract in melena. In addition, fresh blood is released during hematochezia, while digested blood is released during the melena.
The below infographic presents the differences between hematochezia and melena in tabular form for side-by-side comparison.
Summary – Hematochezia vs Melena
Hematochezia and melena are two symptoms of gastrointestinal bleeding. Hematochezia refers to the passing of fresh red colour blood with stools. Blood in hematochezia originates from the lower GI tract. Melena refers to the passing of black tarry stools that has a foul odour. Blood in melena originates from the upper GI tract. So, this is the summary of the difference between hematochezia and melena.
1. “Hematemesis, Melena, and Hematochezia.” Clinical Methods – NCBI Bookshelf.
2. Gotter, Ana. “Hematochezia vs Melena: Symptoms, Causes, Diagnosis, Treatment.” Healthline, Healthline Media.