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Gastrointestinal bleeding

Last updated: September 7, 2020


Gastrointestinal (GI) bleeding is a symptom of conditions that damage the wall GI tract. GI bleeding is categorized into upper GI bleeding (UGIB) and lower GI bleeding (LGIB) depending on the source of the bleeding relative to the ligament of Treitz. In the majority of cases, bleeding is localized in the esophagus, stomach, or duodenum (UGIB). LGIB may occur in the rectum, colon, jejunum, and, in rare cases, the ileum. Gastric and duodenal ulcers are the most common causes; angiodysplasia, inflammatory diseases, and carcinomas can also cause GI bleeding. Depending on the source of the bleeding and how long the blood remains in the digestive tract, clinical symptoms may include vomiting blood (hematemesis), tarry black stool (melena), and fresh blood in the stool (hematochezia). Diagnosis includes evaluation of blood loss (e.g., hematocrit) and localization of the source of bleeding (e.g., endoscopy). Hospitalization is essential to monitor for signs of hemodynamic instability and shock caused by anemia and severe blood loss. The source of bleeding can often be located and treated simultaneously during endoscopy with injection therapy (e.g., epinephrine) or ligation.


Most common etiologies of GI bleeding [4]
(UGIB) [5] (LGIB) [6]
Erosive or inflammatory
Traumatic or iatrogenic
  • Lower abdominal trauma
  • Anorectal trauma (e.g., anorectal avulsion, impalement injuries)
  • Following open or endoscopic surgery (e.g., anastomotic bleeding following a gastric bypass)
Other causes

See “Differential diagnosis of lower gastrointestinal bleeding in children.”

Bleeding from the upper respiratory tract (e.g., nocturnal nosebleeds) can be mistaken for GI bleeding because the blood can be swallowed and vomited or appear in the stool as melena. Careful examination and history taking is the key to differentiating respiratory sources of bleeding from GI ones.

Clinical features

Description Cause
  • Vomiting blood, which may be red or coffee-ground in appearance
  • Black, tarry stool with a strong offensive odor
  • Most commonly due to bleeding in the upper GI tract
  • The passage of bright red (fresh) blood through the anus (with or without stool)
    • Colonic bleeding: maroon, jelly-like traces of blood in stools
    • Rectal bleeding: streaks of fresh blood on stools

Both melena and hematochezia can be caused by either UGIB or LGIB.

Unexplained iron deficiency anemia in men or postmenopausal women should raise suspicion for GI bleeding.


In case of hemodynamic instability, hemodynamic resuscitation should be initiated before further diagnostic workup (see “Treatment” below).

Localization of bleeding

  • Definitions
    • Occult GI bleeding: bleeding in quantities too small to be macroscopically observable (requires chemical tests or microscopic examination to be detected)
    • Overt GI bleeding: macroscopically observable bleeding with accompanying clinical symptoms (e.g., anemia, tachycardia)
  • Fecal occult blood test
    • May detect small quantities of blood
    • Cannot differentiate between UGIB and LGIB [9]
    • A positive result should be followed up with endoscopy/colonoscopy.
  • Endoscopy
    • Colonoscopy: a procedure during which a flexible fiber-optic instrument is passed through the anus to visualize the mucosa of the colon
    • Upper endoscopy: a procedure during which a flexible fiber-optic instrument is passed through the mouth to visualize the inner layer of the upper GI tract up to the duodenal papilla
    • Should be performed within 24 hours of admission [10]
    • Used to identify the source of intestinal bleeding (e.g., bleeding vessel, mucosal inflammation)
    • Biopsies can be taken for further diagnosis (e.g., colorectal/gastric carcinoma).
    • Therapy can be initiated immediately (e.g., epinephrine injection therapy, clipping of a bleeding vessel).
  • Nasogastric tube lavage: a procedure in which a nasogastric tube is passed into the stomach and releases small amounts of liquid, which are removed with other contents of the stomach (e.g., blood in the case of GI bleeding)
    • Rule out UGIB.
    • Identify the site of bleeding and possibly initiate therapy.
    • Blood that is bright red or has a coffee-ground appearance indicates UGIB.
    • Results are negative in ∼15% of patients with UGIB.
  • Other: If the above diagnostics fail to locate the source of the bleeding, evaluate for small bowel bleeding.

Approach according to the patient's hemodynamic status

Hemodynamically stable patient Hemodynamically unstable patient
Suspected UGIB
Suspected LGIB

Forrest classification

The Forrest classification describes the type of lesion seen during endoscopy and helps to evaluate the risk of renewed hemorrhage (without the need for repeated intervention).


Description Risk of recurring hemorrhage
I Active hemorrhage
Ia Spurting arterial hemorrhage 85–100% of cases
Ib Oozing hemorrhage 25–55% of cases
II Inactive hemorrhage
IIa Lesion with a visible vessel 20–50% of cases
IIb Lesion with an adherent clot 20–40% of cases
IIc Flat lesion covered with hematin 5–10% of cases
III Lesion without active hemorrhage (flat ulcer base) 5% of cases

Laboratory tests [12]


Initial management [12]

If there is any suspicion of GI bleeding, two large-caliber peripheral venous catheters should be inserted and preparations should be made for a possible blood transfusion.

Interventions to stop bleeding [14][15]

  • Endoscopy
    • Used to locate the site of the (suspected) bleeding and to initiate therapy
  • Angiography: vasoconstriction of a bleeding vessel via e.g., intraarterial vasopressin infusion or embolization
  • Surgery (laparotomy): if bleeding cannot be contained through endoscopic intervention (rarely the case)

Treatment of underlying disease

See “Treatment” sections in “Crohn disease“, “Ulcerative colitis“, “Peptic ulcer disease“, “Hemorrhoids“, “Intestinal ischemia“, “Gastric cancer“, “Colorectal cancer“, and “Portal hypertension.“

Differential diagnoses

Upper GI bleed

Lower GI bleed

The differential diagnoses listed here are not exhaustive.


We list the most important complications. The selection is not exhaustive.


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