What is hematochezia?

Hematochezia: Definition, Evaluation, and Management

Hematochezia is the passage of bright red blood or clots from the rectum, typically indicating bleeding from a source in the lower gastrointestinal tract. 1

Definition and Clinical Significance

Hematochezia presents as bright red blood per rectum and must be differentiated from melena (darkened, digested blood), which typically suggests an upper gastrointestinal source. Key characteristics include:

• Bright red blood that may drip or squirt into the toilet bowl 1
• May be mixed with stool or appear separately 1
• Requires prompt evaluation as it can indicate significant pathology

Common Causes

The most common causes of hematochezia include:

• Diverticulosis (20-41% of cases) 1
• Angiodysplasia (2-40% of cases) 1
• Hemorrhoids (common but often overdiagnosed) 1
• Ischemic colitis 1
• Colorectal cancer/polyps (6-15% of cases) 1
• Inflammatory bowel disease and other colitis 1
• Anorectal conditions (fissures, ulcers) 1

It's important to note that approximately 10-15% of patients presenting with acute severe hematochezia actually have an upper gastrointestinal source of bleeding identified on upper endoscopy 1.

Diagnostic Approach

Initial Assessment

1. Hemodynamic evaluation: Assess vital signs, including blood pressure and heart rate to determine severity 2
2. Laboratory tests: Complete blood count, serum electrolytes, BUN, creatinine, and coagulation studies 1
3. Blood typing and cross-matching for potential transfusion in severe cases 1

Endoscopic Evaluation

• Anoscopy and flexible sigmoidoscopy are the minimum recommended procedures for bright red rectal bleeding 1
• Complete colonoscopy is indicated when:
  • Bleeding is atypical for hemorrhoids
  • No source is evident on anorectal examination
  • Patient has significant risk factors for colonic neoplasia 1
  • There is suspicion of a more proximal source of bleeding 1

Imaging Studies

• CT Angiography (CTA) is recommended as the first-line imaging alternative to endoscopy for stable patients with gastrointestinal bleeding 2
• Nuclear Medicine Labeled Red Cell Scan can detect slower bleeding rates (0.05-0.1 mL/min) 2

Management Considerations

Blood Transfusion Strategy

• Restrictive transfusion strategy with hemoglobin trigger of <70 g/L (target 70-90 g/L) for most patients 2
• Higher threshold of 80 g/L for patients with cardiovascular disease 2
• Maintain mean arterial pressure >65 mmHg while avoiding fluid overload 2

Endoscopic Management

• Early endoscopy (within 24 hours) is recommended for suspected GI bleeding 2
• Endoscopic intervention options include clipping, thermal therapy, injection therapy, and band ligation for active bleeding 2

Special Considerations

• Anorectal varices due to portal hypertension should not be confused with hemorrhoids and require different management approaches 1
• Patients with hematochezia but negative initial evaluations may require small bowel evaluation if bleeding persists 2
• Fecal occult blood should not be attributed to hemorrhoids until the colon is adequately evaluated 1

Follow-up and Prevention

• Iron supplementation for patients discharged with anemia 2
• Gastroenterology follow-up within 2 weeks if discharged 2
• Screening for H. pylori and eradication if positive in relevant cases 2

Important Clinical Pearls

• The incidence of lower gastrointestinal bleeding increases significantly with age 1
• Physicians' clinical assessment alone cannot reliably predict which patients have significant pathology 3
• Anemia due to hemorrhoidal disease is rare (0.5 patients/100,000 population) 1
• Patients with hematochezia who have substantial lesions are more likely to report blood mixed within stool, more frequent episodes, and shorter duration of bleeding before seeking medical care 3