Bloody Stool: Causes

What causes bloody stool?

Blood in the stool can indicate a relatively mild condition, such as hemorrhoids or constipation, or it can be due to a serious, even life-threatening condition, such as esophageal varices or colon cancer. Certain medications, such as aspirin, can also cause bloody stool.

Black, tarry stools usually indicate that the blood is coming from the upper gastrointestinal tract (esophagus, stomach and duodenum), while red or maroon-colored stools often originate from bleeding in the lower gastrointestinal tract (colon, rectum and anus). Bloody stool that is associated with dizziness, diarrhea, or vomiting blood should be immediately evaluated in an emergency setting. However, a diagnosis of the cause of blood in the stool can be delayed or missed because tiny amounts of blood may not be noticeable for long periods of time.

Upper gastrointestinal tract causes of bloody stool

Causes of bloody stool related to the upper gastrointestinal tract include:

• Bleeding peptic ulcer

• Blood vessel malformation

• Esophageal trauma

• Esophageal varices

• Gastritis

• Gastroenteritis

• Stomach cancer

• Stomach varices

• Swallowed blood from nosebleed

Lower gastrointestinal tract causes of bloody stool

Causes of bloody stool related to the lower gastrointestinal tract include:

• Anal fissure

• Anal sex

• Blood vessel malformation

• Bowel ischemia or bowel obstruction

• Colon cancer

• Constipation

• Diverticulosis

• Gastroenteritis

• Hemorrhoid

• Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)

• Intestinal infection (food poisoning)

• Intestinal polyps or intestinal tumor

• Meckel’s diverticulum (an abnormal pouch near the lower end of the small intestine)

• Rectal prolapse

Other causes of bloody stool

Bloody stool can be caused by:

• Medication side effects

• Radiation therapy

Serious or life-threatening causes of bloody stool

Any type of blood in the stool should be evaluated by a health care professional. In some cases, bleeding may accompany a serious or life-threatening condition including:

• Bleeding peptic ulcer

• Bowel obstruction

• Food poisoning

• Ruptured esophageal varices

• Severe abdominal trauma

What are the potential complications of bloody stool?

Over time, bloody stool can lead to serious complications including:

• Anemia

• Severe blood loss

• Shock