Lower Gastrointestinal Bleeding (LGIB)

What is Lower Gastrointestinal Bleeding

Lower gastrointestinal (GI) bleeding is the result of bleeding from the colon, rectum, or anal area. The colon is the last part of the digestive tract, where stool, also called feces, is formed.

If you have lower GI bleeding, you may see blood in or on your stool. It may be bright red.

Bleeding that originates distal to the ligament of Treitz is considered LGIB . There is wide variability in clinical presentation based on the volume of blood loss and whether the bleeding is acute or chronic, overt or occult.

Lower GI bleeding often stops without treatment. Continued or heavy bleeding needs emergency treatment at the hospital.

How common is Lower Gastrointestinal Bleeding

The annual incidence of LGIB has steadily risen from 20 to 30 per 100,000 population during the past 2 decades, whereas hospitalization for upper gastrointestinal bleeding (UGIB) has declined by 50%

Who are at increased risk? 

Age is the strongest risk factor with a 200-fold increased incidence between the third to ninth decades of life. This relationship is explained by the large proportion of LGIB arising from age-related gastrointestinal (GI) pathophysiologic conditions such as diverticulosis, angiodysplasia, and ischemic colitis from atherosclerosis. High nonsteroidal antiinflammatory drug (NSAID) consumption in this population, including cyclooxygenase-2 (COX-2) inhibitors, compounds the risk of bleeding from diverticulosis and angiodysplasia.

What are the causes?

Lower GI bleeding may be caused by:

  • A condition that causes pouches to form in the colon over time (diverticulosis).
  • Swelling and irritation (inflammation) in areas with diverticulosis (diverticulitis).
  • Inflammation of the colon (inflammatory bowel disease).
  • Swollen veins in the rectum (hemorrhoids).
  • Painful tears in the anus (anal fissures), often caused by passing hard stools.
  • Cancer of the colon or rectum.
  • Noncancerous growths (polyps) of the colon or rectum.
  • A bleeding disorder that impairs the formation of blood clots and causes easy bleeding (coagulopathy).
  • An abnormal weakening of a blood vessel where an artery and a vein come together (arteriovenous malformation).

Common Causes of Lower Gastrointestinal Bleeding

EtiologyEstimated Percentage
Small bowel6
No site8
Upper gastrointestinal source8

Do all angiodysplasias cause Lower Gastrointestinal Bleeding? 

No. Asymptomatic angiodysplasias are occasionally found during routine endoscopy. They are more common among older adults (> 50 years). Most (75%) bleeding colonic angiodysplasia are found in the right colon. Small bowel angiodysplasia may occur anywhere, limiting the ability for complete endoscopic treatment by injection, laser, clips, or thermal techniques. Endoscopic treatment has been shown to be effective, however, and should be attempted if they are within reach, are actively bleeding, or are thought to be the source of bleeding or anemia. One should be cautious with any endoscopic treatment of these lesions, especially in the thin-walled right colon. Long-term octreotide may have a role in reducing transfusion requirements in patients with multiple or difficult-to-reach small bowel angiodysplasias.

What increases the risk?

You are more likely to develop this condition if:

  • You are older than 60 years of age.
  • You take aspirin or NSAIDs on a regular basis.
  • You take anticoagulant or antiplatelet drugs.
  • You have a history of high-dose X-ray treatment (radiation therapy) of the colon.
  • You recently had a colon polyp removed.

What are the symptoms of Lower Gastrointestinal Bleeding?

Symptoms of this condition include:

  • Bright red blood or blood clots coming from your rectum.
  • Bloody stools.
  • Black or maroon-colored stools.
  • Pain or cramping in the abdomen.
  • Weakness or dizziness.
  • Racing heartbeat.

How is this diagnosed?

This condition may be diagnosed based on:

  • Your symptoms and medical history.
  • A physical exam. During the exam, your health care provider will check for signs of blood loss, such as low blood pressure and a rapid pulse.
  • Tests, such as:
    • Flexible sigmoidoscopy. In this procedure, a flexible tube with a camera on the end is used to examine your anus and the first part of your colon to look for the source of bleeding.
    • Colonoscopy. This is similar to a flexible sigmoidoscopy, but the camera can extend all the way to the uppermost part of your colon.
    • Blood tests to measure your red blood cell count and to check for coagulopathy.
    • An imaging study of your colon to look for a bleeding site. In some cases, you may have X-rays taken after a dye or radioactive substance is injected into your bloodstream (angiogram).

What role does urgent colonoscopy have in the diagnosis of Lower Gastrointestinal Bleeding? 

Ileocolonoscopy, following a rapid polyethylene glycol bowel purge, is the diagnostic method of choice for LGIB. This can establish a diagnosis in 74% to 90% of cases. Small studies have shown that alternative preparations that capitalize on the natural cathartic properties of severe colonic bleeding, augmented with tap water enemas, hydroflush waterjet irrigation pumps, and mechanical suction, offer a rapid purge-free evaluation with high diagnostic and intervention yields. To date, no study has shown that urgent colonoscopy improves clinical outcomes or lowers costs when compared with routine elective colonoscopy.

What is the role of nuclear medicine scintigraphy, computed tomography (CT) and magnetic resonance enteroclysis, CT angiography, interventional angiography, and barium small bowel follow through in the diagnosis and treatment of LGIB? 

All represent second-line tests following a nondiagnostic upper and lower endoscopy in a hemodynamically stable patient—especially in the setting of ongoing bleeding. 

Diagnostic Modalities for Lower Gastrointestinal Bleeding

Imaging ModalitySite DetectedActive BleedingTherapeutic AbilityAdvantages and Disadvantages





Can also visualize nonbleeding lesions and detect recent bleeding.
Cross-sectional CT enteroclysis MR enteroclysis




Can visualize nonbleeding lesions and detect recent bleeding.




0.05-0.1 mL/min
0.3-1 mL/min
0.5-1 mL/min

Can detect slow bleeding or delayed bleeding. Variable accuracy.
Rapid, accurate; can also detect recent bleeding.






CT, Computed tomography; CT-A, computed tomography angiography; DBE, double balloon endoscopy; MR, magn

How can continued or recurrent Lower Gastrointestinal Bleeding be determined? 

This determination can be challenging. Frequent monitoring of the patient’s hematocrit should be performed. However, early in presentation, the hematocrit is likely to underestimate the degree of blood loss because of volume contraction. On the other hand, through dilutional effects from crystalloid hydration, the hematocrit may decrease—even in the absence of ongoing active bleeding. This decrease may not represent continued hemorrhage. Hemodynamic parameters should be monitored for signs of worsening volume depletion, especially in the setting of adequate volume resuscitation.

What are the more common causes of small intestinal bleeding? 

Small intestinal bleeding is commonly caused by ulceration (Crohn’s, NSAIDs), angiodysplasias, and malignancy.

What endoscopic methods are available for hemostasis? 

Diverticular bleeding can be treated with submucosal injections of dilute epinephrine, or with contact electrocautery devices, or with hemostatic metallic clip placement. Using suction to evert a diverticulum followed by band ligation or hemostatic metallic clip placement has also been safely used. Angiodysplasias can be treated with contact electrocautery, argon plasma coagulation, or metallic clips. Visible vessels and postpolypectomy bleeding can be managed with electrocautery or endoscopically deployed metallic clips.

How is this treated?

Treatment for this condition depends on the cause of the bleeding. Heavy or persistent bleeding is treated at the hospital. Treatment may include:

  • Getting fluids through an IV tube inserted into one of your veins.
  • Getting blood through an IV tube (blood transfusion).
  • Stopping bleeding through high-heat coagulation, injections of certain medicines, or applying surgical clips. This can all be done during a colonoscopy.
  • Having a procedure that involves first doing an angiogram and then blocking blood flow to the bleeding site (embolization).
  • Stopping some of your regular medicines for a certain amount of time.
  • Having surgery to remove part of the colon. This may be needed if bleeding is severe and does not respond to other treatment.

What are the first steps taken in the management of a patient with significant LGIB?

• Stabilize and resuscitate.

• Place at least one large-bore peripheral intravenous line (lactated Ringer or normal saline)

• Evaluate hemodynamic status: blood pressure, pulse, orthostatic vital signs if stable.

• Supplement oxygen by nasal cannula.

• Order laboratory tests: complete blood count, electrolytes, international normalized ratio in patients suspected of having a coagulopathy (liver disease or on warfarin), and type and screen for packed RBCs.

• Consider platelet transfusion if the patient is on aspirin.

• Get electrocardiogram for those with known arteriosclerotic heart disease or older than 50 years.

• Perform a physical examination:

• Ear, nose, and throat examination for telangiectasias or pigmented macules may indicate Osler-Weber-Rendu disease, Peutz-Jeghers syndrome, or vascular ectasia in the gut.

• Cardiac auscultation for aortic stenosis (Heyde syndrome) is perhaps associated with angiodysplasia of the GI tract and acquired type IIA von Willebrand syndrome.

• Abdominal examination should assess for bowel sounds, abdominal bruit, tenderness, masses, and surgical scars. Hepatosplenomegaly, ascites, or caput medusae may indicate chronic liver disease with portal hypertension, suggesting an esophageal, gastric, or colonic variceal bleed.

• Cutaneous purpura or petechiae suggest a coagulopathy, whereas spider angiomata or jaundice may be another indicator of chronic liver disease.

• Joint hypermobility, swelling, or deformity may indicate a connective-tissue disorder and possible use of aspirin or NSAIDs.

• Digital rectal examination is mandatory for all patients with LGIB to evaluate for prolapsed internal hemorrhoids or masses and to characterize the color and consistency of blood and stool in the rectal vault.

What is the role of surgery in LGIB? 

It is good practice to obtain surgical consultation in cases of GI hemorrhage. When there is massive hemorrhage with hemodynamic instability or recurrent bleeding despite other attempted therapies, surgery for definitive therapy may become necessary. If surgery is necessary, an accurate diagnosis is vital because extent of resection and consequent postoperative morbidity and mortality depend on localization of bleeding (small bowel, cecum/ascending, transverse, right colon) before surgery

How is postpolypectomy Lower Gastrointestinal Bleeding best managed? 

Postpolypectomy bleeding is the cause of 2% to 5% of all acute LGIB. Most bleeding occurs at a mean of 5 days after polypectomy. The majority of patients have been receiving NSAIDs or aspirin, antiplatelet agents, thrombin inhibitors, or anticoagulants. As such, fresh frozen plasma or platelet transfusions may be required along with endoscopic treatment. Endoscopic treatment has been shown to be successful in 95% of cases.

Follow these instructions at home:

  • Take over-the-counter and prescription medicines only as told by your health care provider. You may need to avoid aspirin, NSAIDs, or other medicines that increase bleeding.
  • Eat foods that are high in fiber. This will help keep your stools soft. These foods include whole grains, legumes, fruits, and vegetables. Eating 1–3 prunes each day works well for many people.
  • Drink enough fluid to keep your urine clear or pale yellow.
  • Keep all follow-up visits as told by your health care provider. This is important.

Contact a health care provider if:

  • Your symptoms do not improve.

Get help right away if:

  • Your bleeding increases.
  • You feel light-headed or you faint.
  • You feel weak.
  • You have severe cramps in your back or abdomen.
  • You pass large blood clots in your stool.
  • Your symptoms get worse.

What is the prognosis of Lower Gastrointestinal Bleeding 

Most cases of LGIB (65%-85%) are self-limited and uncomplicated; however, mortality can vary from 4% to as high as 23% if the bleeding occurred after hospitalization. Patients with massive LGIB requiring 4 to 6 units of red blood cells (RBCs) in 24 hours, who rebleed after a cessation period of 24 hours, or bleed for greater than 72 hours are at the highest risk of death. Traditionally, patients who meet one of these benchmarks are considered for surgery. This recommendation may not be as strong as it was in the past as recent studies reveal that large numbers of patients who met the aforementioned criteria have been successfully managed with nonoperative care.

How is history important in assessing a patient with LGIB? 

Clinical Characteristics and Historical Features in Suspected LGIB cases

Bleeding SourceAppearance of bloodVolumeBleeding OnsetSigns/Symptoms Associations
Diverticular4+2+1+4+AcutePainless, NSAIDs?
Colitis (UC, Crohn’s)4+2+1+2+ChronicDiarrhea, ABD pain, tenesmus
Malignancy3+2+2+1+ChronicPainless, weight loss, stool changes147.6131
Angiodysplasia4+3+1+3+Acute/IPainless, Heyde syndrome, prostate/cervical radiation
Hemorrhoidal4+1+1+Acute/IBlood around stool on tissue, dripping in toilet
Ischemic4+1+1+AcuteHypotension, bleeding preceded by ABD pain
Postpolypectomy4+2+3+AcuteHistory of polypectomy in past 14 days
Infectious3+1+1+Acute/SADiarrhea, fevers, acutely ill
Aortoenteric fistula4+1+4+AcuteHistory of AAA repair
UGIB1+3+4+4+AcuteAbdominal pain, NSAIDs, + NG lavage

AAA, Abdominal aortic aneurysm; ABD, abdominal; BRB, bright red blood; , intermittent; LGIB, lower gastrointestinal bleeding; NG, nasogastric; NSAID, nonsteroidal antiinflammatory drug; SA , subacute; UC, ulcerative colitis; UGIB, upper gastrointestinal bleeding.

What is the natural history of LGIB from diverticulosis?

  • • Bleeding is a complication in 17% of patients with colonic diverticular disease.
  • • Approximately 80% of patients stop bleeding spontaneously.
    • • Approximately 70% will not rebleed and will not require further treatment.
    • • Approximately 30% will rebleed and require treatment.

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