Gastrointestinal Bleeding, Acute Lower

Essentials of Diagnosis

• Hematochezia usually present

• 10% of cases of hematochezia are due to upper gastrointestinal source

• Stable patients can be evaluated by colonoscopy

• Massive active bleeding calls for evaluation with sigmoidoscopy, upper endoscopy, angiography, or nuclear bleeding scan

General Considerations

• Lower GI bleeding is defined as that arising below the ligament of Treitz, ie, small intestine or colon; up to 95% of cases derive from the colon

• Lower tract bleeding

  • 33% less common than upper tract bleeding

  • Tends to have a more benign course

  • Is less likely to present with shock or orthostasis (< 20%) or to require transfusions (< 40%)

• Spontaneous cessation in > 75%; hospital mortality in < 4%

• Most common causes in patients age < 50 years

  • Infectious colitis

  • Anorectal disease

  • Inflammatory bowel disease

• Most common causes in patients age > 50 years

  • Diverticulosis (over 50% of cases)

  • Angioectasias (5%)

  • Neoplasms (polyps or carcinoma) (7%)

  • Ischemia

  • Radiation-induced proctitis

  • Solitary rectal ulcer

  • Nonsteroidal anti-inflammatory drug (NSAID)-induced ulcers

  • Small bowel diverticula

  • Colonic varices

• Risk of lower GI bleeding is increased in patients taking

  • Aspirin

  • Nonaspirin antiplatelet agents

  • Nonsteroidal anti-inflammatory drugs (NSAIDs)

• Diverticular bleeding

  • Acute, painless, large-volume maroon or bright red hematochezia occurs in 3–5% of patients with diverticulosis, often associated with the use of NSAIDs

  • Bleeding more commonly originates on the right side

  • > 95% require less than 4 units of blood transfusion

  • Bleeding subsides spontaneously in 80% of patients but may recur in up to 25%

• Angioectasias

  • Painless bleeding ranging from occult blood loss to melena or hematochezia

  • Bleeding most commonly originates in the cecum and ascending colon

  • Causes: congenital; hereditary hemorrhagic telangiectasia; autoimmune disorders, typically scleroderma

• Neoplasms: benign polyps and carcinoma cause chronic occult blood loss or intermittent anorectal hematochezia

• Anorectal disease

  • Small amounts of bright red blood noted on the toilet paper, streaking of the stool, or dripping into the toilet bowl

  • Clinically significant blood loss can sometimes occur

• Ischemic colitis

  • Hematochezia or bloody diarrhea associated with mild cramps

  • In most cases, bleeding is mild and self-limited

Demographics

• Diverticular bleeding is more common in patients age > 50 years

• Angiodysplasia bleeding is more common in patients age > 70 years and in those with chronic kidney disease

• Ischemic colitis is most commonly seen

  • In older patients due to atherosclerotic disease—postoperatively, after ileoaortic or abdominal aortic aneurysm surgery

  • In younger patients due to vasculitis, coagulation disorders, estrogen therapy, and long-distance running

Symptoms and Signs

• Brown stools mixed or streaked with blood suggest rectosigmoid or anal source

• Painless large-volume bleeding suggests diverticular bleeding

• Maroon stools suggest a right colon or small intestine source

• Black stools (melena) suggest a source proximal to the ligament of Treitz, but dark maroon stools arising from small intestine or right colon may be misinterpreted as "melena"

• Bright red blood per rectum occurs uncommonly with upper tract bleeding and almost always in the setting of massive hemorrhage with shock

• Bloody diarrhea associated with cramping abdominal pain, urgency, or tenesmus suggests inflammatory bowel disease (especially ulcerative colitis), infectious colitis, or ischemic colitis

Differential Diagnosis

• Diverticulosis

• Angioectasias, eg, idiopathic arteriovenous malformation, CREST syndrome, hereditary hemorrhagic telangiectasias

• Colonic polyps

• Colorectal cancer

• Inflammatory bowel disease

• Hemorrhoids

• Anal fissure

• Ischemic colitis

• Infectious colitis

• Radiation colitis or proctitis

• NSAID-induced ulcers of small bowel or right colon

Laboratory Tests

• Complete blood count, including platelet count

• Prothrombin time/INR

• Serum creatinine, blood urea nitrogen

• Type and cross-match

Imaging Studies

• In most settings, multidetector CT angiography is preferred to technetium-labeled red blood cell scanning to detect active arterial bleeding and to help localize bleeding to the small intestine, right colon, or left colon

• Urgent angiography

  • Performed if scintigraphy or CT angiography demonstrates active bleeding in an attempt to localize the bleeding site and make embolization therapy possible

  • May be performed without first attempting a scintigraphy or CT angiography in patients with massive lower gastrointestinal bleeding and continued hemodynamic instability

Diagnostic Procedures

• Nasogastric tube aspiration to exclude upper tract source

• Anoscopy

• Colonoscopy

  • Preferred initial study in most cases of acute, large-volume bleeding requiring hospitalization

  • However, the timing of this procedure is controversial

    • One trial compared colonoscopy within 24 hours versus elective colonoscopy

    • Colonoscopy within 24 hours did not reduce length of stay, rebleeding, or mortality

    • Thus, patients with stable vital signs and whose lower gastrointestinal bleeding appears to have stopped, colonoscopy can be performed electively within 24–36 hours of admission after appropriate resuscitation and bowel cleansing

• Small intestine push enteroscopy or video capsule imaging in patients with unexplained recurrent hemorrhage of obscure origin, suspected from the small intestine

• Upper endoscopy in massive hemotochezia to exclude upper GI source

Surgery

• Surgery indicated in patients with ongoing bleeding that requires > 6 units of blood transfusion within 24 hours or > 10 total units and in whom endoscopic or angiographic therapy failed

• Limited resection of the bleeding segment of small intestine or colon, if possible

• Total abdominal colectomy with ileorectal anastomosis, if bleeding site cannot be precisely identified

Therapeutic Procedures

• Therapeutic colonoscopy: high-risk lesions (eg, diverticulum with active bleeding or a visible vessel, or an angioectasia) can be treated endoscopically with saline or epinephrine injection, cautery (bipolar or heater probe), application of metallic clips or bands, and application of a hemostatic powder (TC-325)

• Angiography with selective embolization achieves immediate hemostasis in more than 95% of patients when a bleeding lesion is identified

Complications

• Major complications from intra-arterial embolization (mainly ischemic colitis) occur in 5% of patients; rebleeding occurs in up to 25%

Prognosis

• 25% of patients with diverticular hemorrhage have recurrent bleeding

When to Admit

• All patients with significant hematochezia