Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Some Causes and Features of Gastrointestinal Bleeding

Some Causes and Features of Gastrointestinal Bleeding


Common Features†


Upper digestive tract (indicated by vomiting blood or dark brown material)

Ulcers or erosions of the esophagus, stomach, or first part of the small intestine (duodenum)

Pain that

  • Is steady and mild or moderately severe

  • Is usually located just below the breastbone

  • May awaken the person during the night and/or be relieved by eating

Painless ulcers can also cause bleeding

Upper GI endoscopy (examination of esophagus, stomach, and duodenum using a flexible viewing tube called an endoscope)

Usually very heavy bleeding

Upper GI endoscopy

In people who vomited one or more times before they started vomiting blood

Sometimes pain in the lower chest during vomiting

Upper GI endoscopy

Abnormal connections between the arteries and veins (arteriovenous malformations) in the intestine

Usually no other symptoms

Upper GI endoscopy

Lower digestive tract (indicated by passing blood in the stool)

Bright red blood only on toilet paper, dripping in the bowl, or on the surface of formed stools

Anoscopy (examination of the anus and rectum with a short, rigid tube) or sigmoidoscopy

Pain during bowel movements

Bright red blood only on toilet paper or on the surface of formed stools

Fissure seen during the doctor's examination

A doctor’s examination alone

Abnormal blood vessels (angiodysplasia) in the intestine

Painless, bright red blood from the rectum (hematochezia)

Usually in people over age 60 (most common cause of large intestine bleeding in this age group)

Colonoscopy (examination of the entire large intestine, rectum, and anus using an endoscope)

Bloody diarrhea, fever, and abdominal pain


Stool tests to look for infectious organisms

Sometimes CT scan

Sometimes fatigue, weakness, and/or a bloating sensation

Usually in middle-aged or older people

Colonoscopy and biopsy (examination of tissue samples taken from the lining of the intestine)

Often no other symptoms


Painless hematochezia

Sometimes in people already known to have diverticular disease


Sometimes CT scan or CT angiography

Rarely angiography (x-rays taken after injecting a dye into an artery using a catheter)

Bloody diarrhea, fever, and abdominal pain and cramps

Sometimes in people who have had several episodes of bleeding from the rectum

Colonoscopy and biopsy

* Causes are listed in order from the most common to the least.

† Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present.

‡ Although a doctor's examination is always done, it is mentioned in this column only if the diagnosis can sometimes be made by the doctor's examination alone, without any testing.

CT = computed tomography; GI = gastrointestinal.