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Overview of Gastrointestinal Bleeding


Parswa Ansari

, MD, Hofstra Northwell-Lenox Hill Hospital, New York

Reviewed/Revised May 2023
Topic Resources

Hematochezia is the passage of gross blood from the rectum and usually indicates lower GI bleeding but may result from vigorous upper GI bleeding with rapid transit of blood through the intestines.

Melena is black, tarry stool and typically indicates upper GI bleeding, but bleeding from a source in the small bowel or right colon may also be the cause. About 100 to 200 mL of blood in the upper GI tract is required to cause melena, which may persist for several days after bleeding has ceased. Black stool that does not contain occult blood may result from ingestion of iron, bismuth, or various foods and should not be mistaken for melena.

Chronic occult bleeding can occur from anywhere in the GI tract and is detectable by chemical testing of a stool specimen.

Acute, severe bleeding also can occur from anywhere in the GI tract. Patients may present with signs of shock Symptoms and Signs Shock is a state of organ hypoperfusion with resultant cellular dysfunction and death. Mechanisms may involve decreased circulating volume, decreased cardiac output, and vasodilation, sometimes... read more . Patients with underlying ischemic heart disease may develop angina or myocardial infarction because of coronary hypoperfusion.

Etiology of GI Bleeding

There are many possible causes (see table ), which are divided into upper GI (above the ligament of Treitz), lower GI, and small bowel.

Medications associated with GI bleeding include anticoagulants (eg, heparin, warfarin, dabigatran, apixaban, rivaroxaban, edoxaban), those affecting platelet function (eg, aspirin and certain other nonsteroidal anti-inflammatory drugs [NSAIDs], clopidogrel, selective serotonin reuptake inhibitors [SSRIs]), and those affecting mucosal defenses (eg, NSAIDs).


Common Causes of Gastrointestinal (GI) Bleeding

Upper GI tract

Gastric or duodenal erosions (20–30%)

Erosive esophagitis (5–10%)

Angioma (5–10%)


Lower GI tract (percentages vary with the age group sampled)

Colitis: Radiation, ischemic, infectious

Small-bowel lesions (rare)


Evaluation of GI Bleeding

In acutely ill patients, stabilization with airway management, IV fluids, or transfusions is essential before and during diagnostic evaluation.


History of present illness should attempt to ascertain quantity and frequency of blood passage. However, quantity can be difficult to assess because even small amounts (5 to 10 mL) of blood turn water in a toilet bowl an opaque red, and modest amounts of vomited blood appear huge to an anxious patient. However, most can distinguish between blood streaks, a few teaspoons, and clots.

Patients with hematemesis should be asked whether blood was passed with initial vomiting or only after an initial (or several) nonbloody emesis. In addition, the clinician should ask specific questions to distinguish between hematemesis and hemoptysis because patients may confuse the two symptoms.

Patients with rectal bleeding should be asked whether pure blood was passed; whether it was mixed with stool, pus, or mucus; or whether blood simply coated the stool or toilet paper. Those with bloody diarrhea should be asked about travel or other possible exposure to GI pathogens.

Review of symptoms should include presence of abdominal discomfort, weight loss, easy bleeding or bruising, previous colonoscopy or endoscopy results, and symptoms of anemia (eg, weakness, easy fatigability, dizziness).

Past medical history should inquire about previous GI bleeding (diagnosed or undiagnosed); known inflammatory bowel disease, bleeding diatheses, and liver disease; and use of any medications or drugs that increase the likelihood of bleeding or chronic liver disease (eg, alcohol).

Physical examination

General examination is focused on vital signs and other indicators of shock or hypovolemia Shock Shock is a state of organ hypoperfusion with resultant cellular dysfunction and death. Mechanisms may involve decreased circulating volume, decreased cardiac output, and vasodilation, sometimes... read more (eg, tachycardia, tachypnea, pallor, diaphoresis, oliguria, confusion) and anemia (eg, pallor, diaphoresis). Patients with lesser degrees of bleeding may simply have mild tachycardia (heart rate > 100) or no signs at all.

Orthostatic changes in pulse (a change of > 10 beats/minute) or blood pressure (a drop of 10 mm Hg) often develop after acute loss of 2 units of blood. However, orthostatic measurements are unwise in patients with severe bleeding because they can possibly cause syncope and they generally lack sensitivity and specificity as a measure of intravascular volume, especially in older adults.

External stigmata of bleeding disorders (eg, petechiae, ecchymoses) are sought, as are signs of chronic liver disease (eg, spider angiomas, ascites, palmar erythema) and portal hypertension (eg, splenomegaly, dilated abdominal wall veins).

A digital rectal examination is necessary to search for stool color, masses, and fissures. Anoscopy is done to diagnose hemorrhoids. Chemical testing of a stool specimen for occult blood completes the examination if gross blood is not present.

Red flags

Several findings suggest hypovolemia or hemorrhagic shock:

  • Syncope

  • Hypotension

  • Pallor

  • Diaphoresis

  • Tachycardia

  • Oliguria

Interpretation of findings

The history and physical examination suggest a source of bleeding in about 50% of patients, but findings are rarely diagnostic, and confirmatory testing is required.

Weight loss and anorexia, with or without a change in stool, suggest a GI cancer.

Bloody diarrhea, fever, and abdominal pain suggest ischemic colitis Ischemic Colitis Ischemic colitis is a transient reduction in blood flow to the colon. Symptoms are left lower quadrant pain and rectal bleeding. Diagnosis is by CT or colonoscopy. Treatment is supportive with... read more Ischemic Colitis , inflammatory bowel disease Overview of Inflammatory Bowel Disease Inflammatory bowel disease (IBD), which includes Crohn disease and ulcerative colitis, is a relapsing and remitting condition characterized by chronic inflammation at various sites in the gastrointestinal... read more (eg, ulcerative colitis Ulcerative Colitis Ulcerative colitis is a chronic inflammatory and ulcerative disease arising in the colonic mucosa, characterized most often by bloody diarrhea. Extraintestinal symptoms, particularly arthritis... read more Ulcerative Colitis , Crohn disease Crohn Disease Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract. Symptoms include diarrhea... read more Crohn Disease ), or an infectious colitis (eg, Shigella Shigellosis Shigellosis is an acute infection of the intestine caused by the gram-negative Shigella species. Symptoms include fever, nausea, vomiting, tenesmus, and diarrhea that is usually bloody... read more , Salmonella Nontyphoidal Salmonella Infections Nontyphoidal salmonellae are gram-negative bacteria that primarily cause gastroenteritis, bacteremia, and focal infection. Symptoms may be diarrhea, high fever with prostration, or symptoms... read more Nontyphoidal <i >Salmonella</i> Infections , Campylobacter Campylobacter and Related Infections Campylobacter infections typically cause self-limited diarrhea but occasionally cause bacteremia, with consequent endocarditis, osteomyelitis, or septic arthritis. Diagnosis is by culture... read more , amebiasis Amebiasis Amebiasis is infection with Entamoeba histolytica. It is acquired by fecal-oral transmission. Infection is commonly asymptomatic, but symptoms ranging from mild diarrhea to severe dysentery... read more ).

Hematochezia suggests diverticulosis Colonic Diverticulosis Colonic diverticulosis is the presence of one or more diverticula in the colon. Most diverticula are asymptomatic, but some become inflamed or bleed. Diagnosis is by colonoscopy, capsule endoscopy... read more Colonic Diverticulosis or angiodysplasia Vascular Gastrointestinal Lesions Several distinct congenital or acquired syndromes involve abnormal mucosal or submucosal blood vessels in the gastrointestinal tract. These vessels may cause recurrent bleeding, which is rarely... read more Vascular Gastrointestinal Lesions . Fresh blood only on toilet paper or the surface of formed stools suggests internal hemorrhoids Hemorrhoids Hemorrhoids are dilated vessels of the hemorrhoidal plexus in the anal canal. Symptoms include irritation and bleeding. Thrombosed hemorrhoids are usually painful. Diagnosis is by inspection... read more Hemorrhoids or fissures Anal Fissure An anal fissure is an acute longitudinal tear or a chronic ovoid ulcer in the squamous epithelium of the anal canal. It causes severe pain, sometimes with bleeding, particularly with defecation... read more Anal Fissure , whereas blood mixed with the stool indicates a more proximal source. Occult blood in the stool may be the first sign of colon cancer Colorectal Cancer Colorectal cancer is extremely common. Symptoms include blood in the stool and change in bowel habits. Diagnosis is by colonoscopy. Treatment is surgical resection and chemotherapy for nodal... read more Colorectal Cancer or a polyp Polyps of the Colon and Rectum An intestinal polyp is any mass of tissue that arises from the bowel wall and protrudes into the lumen. Most are asymptomatic except for minor bleeding, which is usually occult. The main concern... read more Polyps of the Colon and Rectum , particularly in patients > 45 years.

Blood in the nose or trickling down the pharynx suggests the nasopharynx as the source.


Several tests are done to help confirm the suspected diagnosis:

  • Complete blood count (CBC), coagulation profile, and often other laboratory studies

  • Nasogastric tube (NGT) for all but those with minimal rectal bleeding

  • Upper endoscopy for suspected upper GI bleeding

  • Colonoscopy for lower GI bleeding (unless clearly caused by hemorrhoids)

  • Sometimes angiography for upper and lower GI bleeding

CBC should be obtained in patients with large-volume or occult blood loss. Patients with more significant bleeding also require coagulation studies (eg, platelet count, prothrombin time [PT], partial thromboplastin time [PTT]) and liver tests (eg, bilirubin, alkaline phosphatase, albumin, aspartate aminotransferase [AST], alanine aminotransferase [ALT]). Type and cross-match are done if bleeding is ongoing. Hemoglobin and hematocrit may be repeated up to every 6 hours in patients with severe bleeding.

Nasogastric aspiration and lavage should be done in all patients with suspected upper GI bleeding (eg, hematemesis, coffee-ground emesis, melena, massive rectal bleeding). Bloody nasogastric aspirate indicates active upper GI bleeding, but about 10% of patients with upper GI bleeding have no blood in the nasogastric aspirate. Coffee-ground material indicates bleeding that is slow or stopped. If there is no sign of bleeding, and bile is returned, the NGT is removed; otherwise, it is left in place to monitor continuing or recurrent bleeding. Nonbloody, nonbilious return is considered a nondiagnostic aspirate.

Upper endoscopy (examination of the esophagus, stomach, and duodenum) should be done for upper GI bleeding. Because endoscopy may be therapeutic as well as diagnostic, it should be done rapidly for significant bleeding but may be deferred for 24 hours if bleeding stops or is minimal. Upper GI barium x-rays have no role in acute bleeding, and the contrast used may obscure subsequent attempts at angiography.

Flexible sigmoidoscopy and anoscopy may be all that is required acutely for patients with symptoms typical of hemorrhoidal bleeding. All other patients with hematochezia should have colonoscopy, which can be done electively after routine preparation unless there is significant ongoing bleeding. In such patients, a rapid prep (5 to 6 L of polyethylene glycol solution delivered via NGT or by mouth over 3 to 4 hours) often allows adequate visualization.

Angiography may be used to localize the source if it cannot be visualized with colonoscopy and ongoing bleeding is sufficiently rapid (> 0.5 to 1 mL/minute). Some angiographers first take a radionuclide scan to focus the examination, because angiography is less sensitive than the radionuclide scan. Angiography is useful in the diagnosis of upper as well as lower GI bleeding and permits certain therapeutic maneuvers (eg, embolization, vasoconstrictor infusion). The American Journal of Gastroenterology’s 2023 updated guidelines on management of patients with acute lower GI bleeding suggest CT angiography as the initial diagnostic test in patients with ongoing hemodynamically significant hematochezia. The decision of whether to proceed with endoscopy or angiography as the initial diagnostic or therapeutic test should be based on the patient's clinical status and on the expertise and infrastructure available at the treating hospital.

Diagnosis of occult bleeding can be difficult, because heme-positive stools may result from bleeding anywhere in the GI tract. Endoscopy is the preferred method, with symptoms determining whether the upper or lower GI tract is examined first. Double-contrast barium enema and sigmoidoscopy can be used for the lower tract when colonoscopy is unavailable or the patient refuses it.

If the results of upper endoscopy and colonoscopy are negative and occult blood persists in the stool, an upper GI series with small-bowel follow-through, CT enterography, small-bowel endoscopy (enteroscopy), capsule endoscopy (which uses a small pill-like camera that is swallowed), technetium-labeled colloid or red blood cell (RBC) scan, and angiography should be considered. Capsule endoscopy is of limited value in an actively bleeding patient.

Treatment of GI Bleeding

  • Secure airway if needed

  • IV fluid resuscitation

  • Blood transfusion if needed

  • Sometimes medications

  • In some, endoscopic or angiographic hemostasis

Hematemesis, hematochezia, or melena should be considered an emergency. Admission to an intensive care unit or other monitored setting, with consultation by both a gastroenterologist and a surgeon, is recommended for all patients with severe GI bleeding. General treatment is directed at maintenance of the airway and restoration of circulating volume. Hemostasis and other treatment depend on the cause of the bleeding.


A major cause of morbidity and mortality in patients with active upper GI bleeding is aspiration of blood with subsequent respiratory compromise. To prevent these problems, endotracheal intubation should be considered in patients who have inadequate gag reflexes or are obtunded or unconscious—particularly if they will be undergoing upper endoscopy.

Fluid resuscitation and blood product transfusion

Intravenous access should be obtained immediately. Short, large-bore (eg, 14- to 16-gauge) IV catheters in the antecubital veins are preferable to a central venous catheter unless a large (8.5 French) sheath is used. IV fluids are initiated immediately, as for any patient with hypovolemia or hemorrhagic shock (see Intravenous Fluid Resuscitation Intravenous Fluid Resuscitation Almost all circulatory shock states require large-volume IV fluid replacement, as does severe intravascular volume depletion (eg, due to diarrhea or heatstroke). Intravascular volume deficiency... read more ). Healthy adults are given normal saline IV in 500- to 1000-mL aliquots until signs of hypovolemia remit—up to a maximum of 2 L (for children, 20 mL/kg, that may be repeated once).

Patients requiring further resuscitation should receive transfusion with packed RBCs. Transfusions continue until intravascular volume is restored and then are given as needed to replace ongoing blood loss. Transfusions in older adults or those with coronary artery disease may be stopped when hemoglobin is stable at 8 unless the patient is symptomatic. Younger patients or those with chronic bleeding are usually not transfused unless hemoglobin is < 7 or they have symptoms such as dyspnea or coronary ischemia.

Platelet count should be monitored closely; platelet transfusion may be required with severe bleeding. Patients who are taking antiplatelet medications (eg, clopidogrel, aspirin) have platelet dysfunction, often resulting in increased bleeding. Platelet transfusion should be considered when patients taking these medications have severe ongoing bleeding, although a residual circulating medication (particularly clopidogrel) may inactivate transfused platelets. If patients are taking an antiplatelet medication or an anticoagulant for a recent cardiovascular indication, a cardiologist should be consulted, if possible, prior to stopping the medication, reversing the medication, or giving a platelet transfusion.

If a significant blood transfusion is required, fresh frozen plasma and platelets also should be transfused along with packed RBCs according to the institution's massive transfusion protocols. If the patient has a coagulopathy, correction with fresh frozen plasma or prothrombin complex concentrate should be considered.

The decision to reverse a patient's anticoagulation or antiplatelet therapy should be made based on the assessed bleeding risk counterbalanced with the patient's thrombotic risk. The currently published guidelines are unable to provide guidelines for treatment with fresh frozen plasma, prothrombin complex concentrates, or other reversal agents because of a paucity of evidence in the literature (see also the American College of Gastroenterology–Canadian Association of Gastroenterology’s 2022 Clinical Practice Guideline: Management of Anticoagulants and Antiplatelets During Acute Gastrointestinal Bleeding and the Periendoscopic Period).


An IV proton pump inhibitor (PPI) may be started in cases of possible upper GI bleeding and should be used if a gastroduodenal ulcer is confirmed as the source of bleeding.

Octreotide (a synthetic analog of somatostatin) is used in patients with suspected variceal bleeding. Octreotide is given as a 50-mcg IV bolus, followed by continuous infusion of 50 mcg/hour.


GI bleeding stops spontaneously in about 80% of patients. The remaining patients require some type of intervention. Specific therapy depends on the bleeding site. Early intervention to control bleeding is important to minimize mortality, particularly in older adults.

For peptic ulcer Peptic Ulcer Disease A peptic ulcer is an erosion in a segment of the gastrointestinal mucosa, typically in the stomach (gastric ulcer) or the first few centimeters of the duodenum (duodenal ulcer), that penetrates... read more Peptic Ulcer Disease , ongoing bleeding or rebleeding is treated with endoscopic coagulation (with bipolar electrocoagulation, injection sclerotherapy, heater probes, or clips) (see the American Journal of Gastroenterology's 2021 ACG Clinical Guideline: Upper Gastrointestinal and Ulcer Bleeding). Hemostatic powder may be used as a temporizing agent, especially for peptic ulcers or cancer. Nonbleeding vessels that are visible within an ulcer crater are also treated. If endoscopic treatments do not stop the bleeding, upper endoscopy should be repeated. If reintervention fails, angiographic embolization of the bleeding vessel may be attempted, or surgery is required to oversew the bleeding site. Angiographic embolization has a higher recurrent bleeding rate than surgery but has the advantage of a lower complication rate and shorter hospital stay. If the patient has been treated medically for peptic ulcer disease but has recurrent bleeding, surgeons do acid-reduction surgery Surgery Surgery at the same time.

Severe, ongoing lower GI bleeding caused by diverticula Colonic Diverticulosis Colonic diverticulosis is the presence of one or more diverticula in the colon. Most diverticula are asymptomatic, but some become inflamed or bleed. Diagnosis is by colonoscopy, capsule endoscopy... read more Colonic Diverticulosis or angiomas Vascular Gastrointestinal Lesions Several distinct congenital or acquired syndromes involve abnormal mucosal or submucosal blood vessels in the gastrointestinal tract. These vessels may cause recurrent bleeding, which is rarely... read more Vascular Gastrointestinal Lesions can sometimes be controlled colonoscopically by clips, electrocautery, coagulation with a heater probe, or injection with dilute epinephrine (see the American Journal of Gastroenterology's 2023 Management of Patients With Acute Lower Gastrointestinal Bleeding: An Updated ACG Guideline). If these methods are ineffective or unfeasible, angiography with embolization or vasopressin infusion may be successful. However, because collateral blood flow to the bowel is limited, angiographic techniques have a significant risk of bowel ischemia or infarction unless super-selective catheterization techniques are used. In most series, the rate of ischemic complications is < 5%. Vasopressin infusion has about an 80% success rate for stopping bleeding, but bleeding recurs in about 50% of patients. Also, there is a risk of hypertension and coronary ischemia. Furthermore, angiography can be used to localize the source of bleeding more accurately.

Polyps can be removed by snare or cautery.

Surgery may be done in patients with continued lower GI bleeding (requiring > 6 units transfusion), but localization of the bleeding site is very important. If the bleeding site cannot be localized, subtotal colectomy is recommended. Blind hemicolectomy (with no preoperative identification of the bleeding site) carries a much higher mortality risk than does directed segmental resection and may not remove the bleeding site; the rebleeding rate is 40%. However, assessment must be expeditious so that surgery is not unnecessarily delayed. In patients who have received > 10 units of packed RBCs, the mortality rate is about 30%.

Acute or chronic bleeding of internal hemorrhoids stops spontaneously in most cases. Patients with refractory bleeding Treatment Hemorrhoids are dilated vessels of the hemorrhoidal plexus in the anal canal. Symptoms include irritation and bleeding. Thrombosed hemorrhoids are usually painful. Diagnosis is by inspection... read more Treatment are treated via anoscopy with rubber band ligation, injection, coagulation, or surgery.

Treatment reference

Geriatrics Essentials: GI Bleeding

Massive GI bleeding is tolerated poorly by older adults. Diagnosis must be made quickly, and treatment must be started sooner than in younger patients, who can better tolerate repeated episodes of bleeding.

Key Points

  • Rectal bleeding may result from upper or lower GI bleeding.

  • Orthostatic changes in vital signs are unreliable markers for serious bleeding.

  • Hematemesis, hematochezia, or melena should be considered an emergency and managed in an intensive care unit or other monitored setting.

  • IV fluid resuscitation should begin immediately and may require transfusion with blood products.

  • About 80% of patients stop bleeding spontaneously; various endoscopic techniques are usually the first choice for the remainder.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

Drugs Mentioned In This Article

Drug Name Select Trade
Albuked , Albumarc, Albuminar, Albuminex, AlbuRx , Albutein, Buminate, Flexbumin, Kedbumin, Macrotec, Plasbumin, Plasbumin-20
GaviLax, GIALAX , GlycoLax, Healthylax, MiraLax, Visine Dry Eye Relief, Vita Health
Anacin Adult Low Strength, Aspergum, Aspir-Low, Aspirtab , Aspir-Trin , Bayer Advanced Aspirin, Bayer Aspirin, Bayer Aspirin Extra Strength, Bayer Aspirin Plus, Bayer Aspirin Regimen, Bayer Children's Aspirin, Bayer Extra Strength, Bayer Extra Strength Plus, Bayer Genuine Aspirin, Bayer Low Dose Aspirin Regimen, Bayer Womens Aspirin , BeneHealth Aspirin, Bufferin, Bufferin Extra Strength, Bufferin Low Dose, DURLAZA, Easprin , Ecotrin, Ecotrin Low Strength, Genacote, Halfprin, MiniPrin, St. Joseph Adult Low Strength, St. Joseph Aspirin, VAZALORE, Zero Order Release Aspirin, ZORprin
Balfaxar, Kcentra
Bynfezia, Mycapssa, Sandostatin, Sandostatin LAR
Adrenaclick, Adrenalin, Auvi-Q, Epifrin, EpiPen, Epipen Jr , Primatene Mist, SYMJEPI, Twinject
Pitressin, Vasostrict
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