What are the causes of gastrointestinal (GI) bleeding?

Causes of Gastrointestinal Bleeding

Gastrointestinal bleeding has distinct causes based on anatomical location, with vascular lesions, peptic ulcer disease, and diverticulosis being the most common etiologies that require prompt identification to reduce morbidity and mortality.

Anatomical Classification of GI Bleeding

GI bleeding is classified based on the anatomical location of the bleeding source:

1. Upper GI Bleeding (above the ampulla of Vater)

   • Peptic ulcer disease
   • Erosive gastritis
   • Esophagitis
   • Varices (esophageal and fundic)
   • Cameron's erosions in hiatal hernias
   • Dieulafoy's lesion
   • Gastric antral vascular ectasia
   • Mallory-Weiss tears
   • Cancer 1

2. Mid GI Bleeding (ampulla of Vater to terminal ileum)

   • Angiodysplasia/vascular ectasias (most common in patients >40 years)
   • NSAID-induced small bowel disease
   • Dieulafoy's lesion (more common in younger patients)
   • Crohn's disease (more common in younger patients)
   • Small bowel tumors (more common in patients <50 years)
   • Hemobilia
   • Hemosuccus pancreaticus
   • Aortoenteric fistula 2

3. Lower GI Bleeding (colon and rectum)

   • Diverticulosis (20-40% of cases)
   • Angiodysplasia (3-40% of cases)
   • Hemorrhoids
   • Ischemic colitis
   • Inflammatory bowel disease
   • Infectious colitis
   • Colorectal cancer/polyps
   • Post-polypectomy bleeding
   • Radiation colitis 2, 3

Age-Related Patterns

The etiology of GI bleeding varies significantly by age:

• Younger patients (<40 years):

  • Dieulafoy's lesion
  • Crohn's disease
  • Small bowel tumors (in patients <50 years)

• Older patients (>40 years):

  • Vascular lesions (up to 40% of small bowel bleeding)
  • Diverticular disease (incidence increases dramatically with age)
  • Angiodysplasia
  • NSAID-induced mucosal injury 2

Risk Factors for GI Bleeding

Several factors increase the risk of GI bleeding:

• Medications:

  • Anticoagulants (particularly warfarin with INR >4.0)
  • NSAIDs (especially high-dose)
  • Antiplatelet agents 4, 1

• Medical conditions:

  • Advanced age (>65 years)
  • History of previous GI bleeding
  • Hypertension
  • Cerebrovascular disease
  • Anemia
  • Malignancy
  • Renal impairment
  • Liver disease with portal hypertension 4

Overlooked Sources of Bleeding

Common sources that may be missed during initial evaluation:

• Upper GI tract:

  • Cameron's erosions in hiatal hernias
  • Fundic varices
  • Dieulafoy's lesion
  • Gastric antral vascular ectasia

• Lower GI tract:

  • Small angiodysplasias
  • Early neoplasms 2

Clinical Pearls and Pitfalls

• In patients with obscure GI bleeding, the source is often a lesion that was overlooked during initial endoscopy rather than a truly occult source.
• Small bowel tumors are the most common cause of obscure bleeding in patients younger than 50 years and should be aggressively investigated.
• Up to 68% of GI bleeding cases without an obvious source on presentation may remain undiagnosed, as bleeding often stops spontaneously 5.
• Warfarin can cause major or fatal bleeding, especially within the first month of therapy and in patients with INR >4.0 4.
• The incidence of lower GI bleeding increases dramatically with age (>200-fold increase from age 20 to 80), primarily due to increasing prevalence of diverticulosis and angiodysplasia 2.

Diagnostic Approach Based on Bleeding Pattern

• Overt bleeding with hemodynamic instability: Urgent endoscopy or angiography
• Chronic intermittent bleeding: Colonoscopy is the preferred initial diagnostic approach
• Obscure GI bleeding with iron deficiency anemia: Capsule endoscopy after negative upper and lower endoscopy
• Severe, life-threatening bleeding with periods of stability: Technetium-99m red blood cell scan followed by angiography or urgent colonoscopy 2

Understanding the diverse causes of GI bleeding is essential for prompt diagnosis and appropriate management, which directly impacts patient outcomes in terms of morbidity and mortality.