What is hematochezia?

Hematochezia: Definition, Causes, and Management

Hematochezia is defined as the passage of bright red blood per rectum, indicating bleeding from a source in the lower gastrointestinal tract. This clinical presentation requires prompt evaluation to identify the source and determine appropriate management 1.

Clinical Significance and Causes

Hematochezia represents a potentially serious condition that can range from mild to life-threatening bleeding. The most common causes include:

• Diverticulosis (30% of cases) 2
• Angiodysplasia (3-40% depending on population) 1
• Hemorrhoids (common in outpatient setting) 1
• Colorectal cancer/polyps (6-15% of cases) 1
• Colitis (inflammatory, ischemic, infectious) (16-21% of cases) 1
• Anorectal conditions (fissures, ulcers) 1
• Anorectal varices (in patients with portal hypertension) 1

Clinical Presentation and Risk Stratification

The presentation of hematochezia varies based on severity:

• Mild hematochezia: Small amounts of bright red blood on toilet paper or coating stool
• Severe hematochezia: Large volume of bright red blood, with or without clots, potentially causing hemodynamic instability

Important risk factors to assess:

• Hemodynamic status (blood pressure, heart rate)
• Hemoglobin drop (≥1.5 g/dL indicates serious bleeding) 1
• Need for blood transfusion
• Age (risk of significant pathology increases with age)
• Comorbidities (especially liver disease, coagulopathy)

Diagnostic Approach

For patients with hematochezia, the following diagnostic algorithm is recommended:

1. Initial assessment:

   • Vital signs to assess hemodynamic stability
   • Digital rectal examination to identify obvious anorectal sources
   • Nasogastric lavage if upper GI source suspected (10-15% of severe hematochezia cases have upper GI source) 1

2. Laboratory evaluation:

   • Complete blood count
   • Coagulation profile
   • Blood typing and cross-matching if severe bleeding

3. Endoscopic evaluation:

   • For mild hematochezia: Anoscopy and flexible sigmoidoscopy as initial approach
   • For severe hematochezia: Urgent colonoscopy after bowel preparation within 24 hours 1, 3
   • Upper endoscopy if nasogastric lavage positive or if colonoscopy negative in severe bleeding 1

4. Imaging studies:

   • CT angiography for active, severe bleeding when endoscopy is not feasible or non-diagnostic
   • Consider CT scan if suspicion of other pathology (abscess, inflammatory bowel disease, neoplasm) 1

Management Principles

Management depends on severity and identified cause:

• Resuscitation for severe bleeding:

  • Crystalloid fluid replacement
  • Blood transfusion (maintain Hb >7 g/dL) 1
  • Correction of coagulopathy

• Endoscopic therapy for active bleeding sources:

  • Injection therapy, thermal coagulation, or mechanical methods (clips, bands)
  • For diverticular bleeding: Epinephrine injection, thermal therapy, or endoclips
  • For angiodysplasia: Argon plasma coagulation or thermal therapy
  • For hemorrhoids: Band ligation, sclerotherapy, or infrared coagulation

• Interventional radiology for persistent bleeding not controlled by endoscopy:

  • Angiography with embolization

• Surgery for uncontrolled bleeding or specific pathology requiring resection

Special Considerations

1. Distinguishing hemorrhoidal bleeding from other sources:

   • Hemorrhoidal bleeding typically presents as bright red blood on toilet paper or coating stool
   • Exclusive reliance on patient description is unreliable; examination is essential 1
   • Hemorrhoids alone do not cause positive fecal occult blood tests 1

2. Anorectal varices vs. hemorrhoids:

   • Anorectal varices are distinct from hemorrhoids and occur in portal hypertension
   • Varices appear as serpiginous submucosal veins crossing the dentate line 1
   • Management differs significantly from hemorrhoids, requiring treatment of underlying portal hypertension 1

3. Colorectal cancer risk:

   • Hematochezia in young adults (<50 years) carries a 2.4-11% risk of colorectal cancer 1
   • Higher risk with accompanying iron deficiency anemia or weight loss 1
   • Colonoscopy is recommended for evaluation of hematochezia regardless of age 1

Pitfalls to Avoid

1. Assuming hemorrhoids are the cause without adequate examination

   • Other serious pathology may be overlooked 1

2. Delaying evaluation in young patients

   • Early-onset colorectal cancer is increasing in incidence 1

3. Failing to consider upper GI sources

   • Up to 15% of severe hematochezia cases have upper GI sources 1

4. Inadequate bowel preparation for colonoscopy

   • Poor visualization may miss significant lesions

5. Overlooking medication effects

   • NSAIDs, anticoagulants, and antiplatelets can exacerbate bleeding

Hematochezia requires thorough evaluation with a structured approach to identify the source and guide appropriate management, as it can be a manifestation of serious underlying pathology including colorectal cancer.