Bloody stools often indicate an injury or disorder in the digestive tract. Your health care provider may use the term "melena" to describe black, tarry, and foul-smelling stools or "hematochezia" to describe red or maroon-colored stools.

Blood seen in the stool can originate anywhere along the intestinal tract.

A black stool usually means that the blood is coming from the upper part of the gastrointestinal (GI) tract (esophagus, stomach, or early small intestine). Passing maroon-colored stools or bright red blood (hematochezia) usually suggests that the blood is coming from the large bowel or the rectum. However, sometimes massive bleeding in the stomach small intestine can cause bright red bloody stools.

The ingestion of black licorice, lead, iron pills, Pepto-Bismol (or similar medications containing bismuth subsalicylate) or blueberries can all also cause black stools. Health care providers can test black stools to confirm the presence of blood.

Bleeding in the esophagus or stomach (such as peptic ulcer disease), can also cause vomiting blood.

Bleeding into the stomach or intestines (GI bleeding) is the most serious source of bloody stools. The color of the stool can suggest the location of the bleeding. However, this is not always reliable and any diagnosis should be confirmed by trying to identify the site of bleeding through endoscopy or x-ray studies.

Black color:

• Bleeding stomach or duodenal ulcer
• Gastritis
• Esophageal varices
• Mallory-Weiss tear (a tear in the esophagus from violent vomiting)

Maroon color:

• All causes of black stool:
  • Bleeding ulcer
  • Gastritis
  • Esophageal varices
  • Mallory-Weiss tear
• Diverticular bleeding
• Vascular malformation
• Intestinal infection (such as bacterial enterocolitis)
• Inflammatory bowel disease
• Tumor
• Colon polyps or colon cancer

Bright red color:

• All causes of black or maroon-colored stool:
  • Bleeding ulcer
  • Gastritis
  • Esophageal varices
  • Mallory-Weiss tear
  • Diverticular bleeding
  • Vascular malformation
  • Intestinal infection
  • Inflammatory bowel disease
  • Tumor
  • Colon polyps or colon cancer
• Hemorrhoids
• Anal fissures