Gastrointestinal bleeding

Last updated: June 29, 2022

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Gastrointestinal (GI) bleeding can be caused by a number of conditions. It can manifest as overt GI bleeding with hematemesis, melena, or hematochezia, or as occult GI bleeding, with nonspecific symptoms related to iron deficiency anemia. GI bleeding can be classified as upper GI bleeding (UGIB) if the site of hemorrhage is proximal to the ligament of Treitz (e.g., esophageal variceal bleeding, bleeding peptic ulcer) or as lower GI bleeding (LGIB) if the site of hemorrhage is distal to the ligament of Treitz (e.g., diverticular bleeding, malignancy, small bowel bleeding). Overt UGIB typically manifests with hematemesis; hematochezia and melena may occur if the bleeding is brisk. Overt LGIB typically manifests with hematochezia; melena may occur if the bleeding is from the small bowel or proximal colon. The initial management of a patient with overt GI bleeding should focus on hemodynamic resuscitation and endoscopic identification of the source of hemorrhage, if feasible, or via angiography, followed by measures to control bleeding (endoscopically, surgically, or via angioembolization). Sigmoidoscopy is an appropriate initial investigation in young patients with scant hematochezia and no features of underlying malignancy or IBD. In all patients (i.e., with overt or occult GI bleeding), the underlying cause should be identified and treated.

See also “Esophageal variceal hemorrhage”.

  • Upper gastrointestinal bleeding (UGIB)
  • Lower gastrointestinal bleeding (LGIB)
  • 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)
  • Obscure gastrointestinal bleeding: gastrointestinal bleeding that persists or recurs after an initial negative evaluation to find the source of bleeding.

Most common etiologies of GI bleeding [3]

Overview of the most common etiologies of GI bleeding
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.


Features of overt GI bleeding
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
  • Can also occur in bleeding from the small bowel or the right colon
  • 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 (e.g., in men or postmenopausal women) should raise suspicion for GI bleeding.

The following recommendations are consistent with the 2019 International Consensus Group (ICG) nonvariceal UGIB guidelines, the 2016 American College of Gastroenterology (ACG) LGIB guideline, the 2014 American Society for Gastrointestinal Endoscopy (AGSE) LGIB guidelines. [9][10][11]

All patients [9][10][11][12][13][14]

Upper endoscopy, colonoscopy, and transcatheter angiography are dual diagnostic/therapeutic procedures that allow rapid localization of the source of bleeding and hemostatic interventions.

Stable patients

Unstable patients

Exercise caution with volume resuscitation in the absence of massive ongoing bleeding or hemorrhagic shock, especially if the source of hemorrhage is inadequately controlled. Aggressive crystalloid and blood product administration in these patients can increase the risk of rebleeding and death. [10][14]

Urgent consultations [15]

Consult surgery and interventional radiology early for patients with ongoing severe hemorrhage and high-risk features of GI bleeding (especially those too unstable to tolerate bowel preparation).

These measures should be initiated as soon as possible prior to procedures (e.g., endoscopy, angioembolization)

Evidence does not support the routine use of tranexamic acid in patients with acute GI bleeding. [22]


All patients with GI bleeding should be risk-stratified to guide the diagnostic and therapeutic approach, timing of endoscopy, and patient disposition.

High-risk features of GI bleeding [10][12][13]

Patient factors

Features at presentation
Interpretation: > 1 feature is associated with a risk of severe or recurrent bleeding
Glasgow Blatchford score [13][25]
Parameters Findings Score
Laboratory features BUN < 18.2 mg/dL 0
18.2 mg/dL–22.3 mg/dL 2
22.4 mg/dL–27.9 mg/dL 3
28 mg/dL–69.9 mg/dL 4
≥ 70 mg/dL 6
Hemoglobin : > 13 g/dL : > 12 g/dL 0
: 12–13 g/dL : 10–12 g/dL 1
: 10–12 g/dL : N/A 3
: < 10 g/dL : < 10 g/dL 6
Clinical features Systolic blood pressure > 110 mm Hg 0
100–109 mm Hg 1
90–99 mm Hg 2
< 90 mm Hg 3
Additional criteria

Heart rate ≥ 100/min

Melena at presentation 1
Syncope at presentation 2
Liver disease 2
Heart failure 2


  • Score 0: low-likelihood of rebleeding or need for urgent intervention
  • Score ≥ 1: higher likelihood of rebleeding and/or need for urgent intervention [26]

Post-endoscopy [10][13][27]

  • Colonoscopy: Inpatient treatment is recommended if there are features requiring intervention or associated with rebleeding.
  • Upper endoscopy: The Forrest classification is commonly used to determine the need for hemostatic interventions during the procedure and can help guide disposition by predicting the risk of rebleeding.
Forrest classification of bleeding peptic ulcers [28]
Stage Description Risk of recurring hemorrhage

Active hemorrhage

(Stage I)

Ia Spurting arterial hemorrhage ∼ 90%
Ib Actively oozing hemorrhage ∼ 50%

Evidence of a recent hemorrhage

(Stage II)

IIa Nonbleeding ulcer with a visible vessel ∼ 50%
IIb Ulcer with an adherent clot ∼ 30%
IIc Flat ulcer with a dark base (covered with hematin) ∼ 10%

Clean-based ulcer

(Stage III)

III Flat ulcer base (no active hemorrhage) < 5%
  • Low risk (Forrest IIc–III): can usually be managed as outpatients with PPI therapy
  • Higher risk (Forrest I–IIb): Typically require inpatient care

Determining patient disposition should be a multifactorial decision based on a combination of risk stratification, patient factors (e.g., functional status, support system), and available healthcare resources. [9][10][12][13]

Inpatient [9][10][12][13][26]

Outpatient [9][10][12][13][26][29]

  • Discharge without a period of observation may be possible for patients with:
  • Discharge after a period of observation can be considered if all the following parameters are met: The optimal duration of the observation period is unclear and practice varies (e.g., 6–24 hours).
  • Follow-up: Advise follow-up within 24 hours (earlier if symptoms recur) for further diagnostic evaluation and long-term management as needed.

Approach to low-risk GI bleeding

Approach to overt GI bleeding

Diagnostic approach for overt GI bleeding [10][30]
Suspected UGIB [13][14] Suspected LGIB [9]
Supportive features [31]
Testing strategy for hemodynamically stable patients
Testing strategy for hemodynamically unstable patient

Laboratory studies [12]

Anemia, low hematocrit, coagulopathy, and elevated BUN at presentation are signs of severe GI bleeding. [10]

An elevated BUN to creatinine ratio in a patient with hematochezia suggests a brisk UGIB. [10][33]

Nasogastric aspirate (NG aspirate) [10]

This test is not routinely recommended other than as an adjunct in patients with hematochezia with only moderate PTP of UGIB as the source. [9]

  • Procedure: Instill 200–300 ml of warm isotonic saline via NG tube, then aspirate gastric contents for inspection. [34]
  • Findings
    • Positive: Bright red blood or coffee-grounds; active UGIB confirmed [13][35]
    • Inconclusive: Nonbloody and nonbilious
    • Negative: Nonbloody and bilious ; active UGIB less likely

In patients with suspected UGIB, nasogastric tube aspiration is poorly sensitive as ∼ 15% of patients with active UGIB can have a false negative result. [13]


These procedures allow for bleeding source identification, diagnostic biopsies (e.g., for gastric or colorectal cancer), and hemostatic interventions (e.g., epinephrine injection, vessel clipping). They should ideally be performed within 24 hours of admission.

EGD [9][10][13][14]

Consider intubation prior to endoscopy if there is a high risk of aspiration.

Colonoscopy [9][10]

  • Preparation
  • Timing [10][39]
    • High-risk clinical features and/or ongoing GI bleeding: within 24 hours of presentation (after rapid bowel prep)
    • All other inpatients: at the next available opportunity (after rapid bowel prep)
  • Findings and further management (see “Treatment” for details)

Lower endoscopy without bowel preparation (including sigmoidoscopy) is not recommended in the workup of acute LGIB. [10]

Angiography [32][33][40]

Optimize hydration before CTA or transcatheter angiography to mitigate the risk of contrast nephropathy (patients with severe GI bleeding are already at high risk due to hypovolemia).

Evaluation of small bowel bleeding [30][41]

Consider the following in addition to CT angiography:

VCE is preferred in hemodynamically stable patients with negative EGD and colonoscopy. Hemodynamically unstable patients with suspected small bowel bleeding should undergo angiography. [30]

Approach [9][10][11]

Endoscopic hemostasis [10][11][13]

  • Indications: any high-risk endoscopic findings
    • Signs of active bleeding
    • Nonbleeding visible vessel
    • Adherent clot [11][13]
  • Modalities [13]

Interventional radiology (angiography) [9][10][11][30][40]

  • Indications
    • Preferred therapy in patients with ongoing GI bleeding and hemodynamic instability refractory to resuscitation
    • An alternative to colonoscopy in patients with acute LGIB who cannot tolerate bowel preparation.
    • Consider in patients with rebleeding or ongoing bleeding despite endoscopic hemostasis. [32]
  • Techniques


  • Indications
    • Consider if other therapeutic options have failed. [9]
    • Consider in hemodynamically unstable patients with ongoing bleeding.
  • Procedure: exploratory laparotomy and surgical hemostasis

CTA for hemorrhage localization prior to surgery can help plan a more targeted intervention (e.g., bowel resection) and reduce perioperative risk (e.g., due to a missed source of bleeding). [10]

Treatment of the underlying cause

Differential diagnoses of upper GI bleeding

Differential diagnoses of lower GI bleeding

The differential diagnoses listed here are not exhaustive.

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

All inpatients

Suspected UGIB

Suspected LGIB

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