Hematochezia vs. Melena

Attribute	Hematochezia	Melena
Definition	Bright red blood in the stool	Dark, tarry stool containing digested blood
Color of Stool	Bright red	Dark, blackish
Causes	Lower gastrointestinal bleeding, hemorrhoids, anal fissures, diverticulosis, colorectal cancer	Upper gastrointestinal bleeding, peptic ulcers, gastritis, esophageal varices, stomach cancer
Associated Symptoms	Abdominal pain, rectal pain, diarrhea, constipation	Abdominal pain, nausea, vomiting, fatigue
Consistency of Stool	Usually liquid or semi-liquid	Thick, sticky, and tar-like
Odor	May have a metallic smell	May have a foul smell
Medical Evaluation	May require colonoscopy, sigmoidoscopy, or other imaging tests	May require upper endoscopy, stool tests, or other imaging tests

Introduction

Hematochezia and melena are two medical terms used to describe different types of gastrointestinal bleeding. While both conditions involve the presence of blood in the stool, they differ in terms of the color, consistency, and location of the bleeding. Understanding the attributes of hematochezia and melena is crucial for accurate diagnosis and appropriate treatment. In this article, we will explore the characteristics of each condition and highlight their key differences.

Hematochezia

Hematochezia refers to the passage of bright red blood in the stool. It is typically indicative of lower gastrointestinal bleeding, originating from the colon, rectum, or anus. The blood in hematochezia is fresh and unaltered by the digestive process, giving it a vibrant red color. Patients with hematochezia may notice blood on the toilet paper, in the toilet bowl, or mixed with their stool.

Common causes of hematochezia include hemorrhoids, anal fissures, diverticulosis, inflammatory bowel disease (such as ulcerative colitis or Crohn's disease), colorectal polyps, and colorectal cancer. In some cases, excessive intake of certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can also lead to gastrointestinal bleeding and hematochezia.

When evaluating a patient with hematochezia, healthcare providers may perform a thorough physical examination, review the patient's medical history, and order diagnostic tests such as colonoscopy, flexible sigmoidoscopy, or imaging studies to identify the source of bleeding. Treatment for hematochezia depends on the underlying cause and may range from conservative measures, such as dietary modifications and medication, to surgical interventions.

Melena

Melena, on the other hand, refers to the passage of dark, tarry stools due to upper gastrointestinal bleeding. The blood in melena has undergone partial digestion in the stomach and small intestine, resulting in its characteristic black appearance. Melena is often associated with bleeding from the esophagus, stomach, or duodenum.

Common causes of melena include peptic ulcers, gastritis, esophageal varices, Mallory-Weiss tears, and stomach cancer. Certain medications, such as iron supplements or bismuth-containing compounds, can also cause the stool to appear black and tarry, mimicking melena. It is important to differentiate true melena from other causes of dark stools to ensure appropriate management.

Diagnosing the underlying cause of melena typically involves a combination of physical examination, medical history review, laboratory tests (including blood counts and coagulation studies), endoscopic procedures (such as esophagogastroduodenoscopy), and imaging studies. Treatment for melena depends on the specific cause and may involve medications to control bleeding, endoscopic interventions, or surgery.

Differences between Hematochezia and Melena

While both hematochezia and melena involve gastrointestinal bleeding, there are several key differences between the two conditions:

• Color: Hematochezia is characterized by bright red blood in the stool, while melena presents as dark, tarry stools.
• Location: Hematochezia typically originates from the lower gastrointestinal tract, including the colon, rectum, or anus. Melena, on the other hand, arises from bleeding in the upper gastrointestinal tract, such as the esophagus, stomach, or duodenum.
• Consistency: Hematochezia is associated with fresh, unaltered blood that may be mixed with the stool or seen separately. Melena, in contrast, results from partially digested blood, giving the stool a sticky, tar-like consistency.
• Causes: Hematochezia is commonly caused by conditions such as hemorrhoids, anal fissures, diverticulosis, inflammatory bowel disease, polyps, or colorectal cancer. Melena, on the other hand, is often associated with peptic ulcers, gastritis, esophageal varices, Mallory-Weiss tears, or stomach cancer.
• Diagnostic Approach: Evaluating hematochezia typically involves colonoscopy, flexible sigmoidoscopy, or imaging studies to identify the source of bleeding. Diagnosing melena, on the other hand, often requires endoscopic procedures like esophagogastroduodenoscopy.

Conclusion

Hematochezia and melena are distinct terms used to describe different types of gastrointestinal bleeding. Hematochezia refers to the passage of bright red blood in the stool, originating from the lower gastrointestinal tract, while melena describes the presence of dark, tarry stools resulting from upper gastrointestinal bleeding. Understanding the attributes and differences between these conditions is crucial for accurate diagnosis and appropriate management. If you experience any signs of gastrointestinal bleeding, it is important to seek medical attention promptly to determine the underlying cause and receive appropriate treatment.