What are the causes of Gastrointestinal (GI) bleeding?

From the Guidelines

Gastrointestinal (GI) bleeding is primarily caused by diverticulosis, inflammatory bowel disease, neoplasms, stress ulcers, surgical anastomoses, vascular lesions such as angiodysplasia, and diverticulosis.

Causes of GI Bleeding

• Diverticulosis: accounting for 30% of cases, with approximately 75% of episodes stopping spontaneously, especially in patients requiring transfusions of <4 units of blood over a 24-hour period 1
• Inflammatory bowel disease (IBD): including ulcerative colitis (UC) and Crohn's disease (CD), where bleeding is caused by inflammation/ulceration of the bowel, and usually resolves with medical treatment 1
• Neoplasms: including cancer and polyps, which can cause bleeding due to tumor erosion into blood vessels
• Stress ulcers: which can cause bleeding due to mucosal erosion and ulceration
• Surgical anastomoses: which can cause bleeding due to anastomotic leakage or ulceration
• Vascular lesions: such as angiodysplasia, which can cause bleeding due to abnormal blood vessel formation
• Other causes: including anorectal varices, ectopic varices, and portal hypertension 1

Clinical Presentation

• Hematochezia: bright red blood per rectum, which can be caused by lower GI bleeding
• Melena: darkened, digested blood per rectum, which suggests an upper GI source of bleeding
• Hemodynamic instability: which can occur due to severe blood loss, and requires immediate medical attention 1

Diagnosis and Management

• Endoscopy: including colonoscopy and sigmoidoscopy, which can help diagnose and treat the cause of bleeding 1
• Imaging techniques: including CT and catheter angiography, which can help localize the source of bleeding 1
• Medical treatment: including intravenous fluid and blood product resuscitation, and medical therapy to control bleeding 1
• Surgical intervention: which may be required in cases of severe bleeding or hemodynamic instability 1

From the Research

Causes of Gastrointestinal (GI) Bleeding

The causes of GI bleeding are diverse and can be categorized into upper and lower GI bleeding.

• Upper GI bleeding can be caused by:
  • Gastric ulcer 2
  • Duodenal ulcer 2
  • Esophageal varices 2
  • Mallory-Weiss tear 2
• Lower GI bleeding can be caused by:
  • Colonic diverticulosis 2, 3
  • Colonic ulcers 2
  • Carcinoma 2
  • Vascular ectasias 2
  • Angiodysplasias 3
  • Neoplasms 3
  • Colitis 3
  • Ischemia 3
  • Anorectal disorders 3
  • Postpolypectomy bleeding 3

Diagnostic Factors

Important diagnostic factors that increase morbidity and mortality include:

• Advanced age 4
• Serious comorbid conditions 4
• Hemodynamic instability 4
• Esophageal varices 4
• Significant hematemesis or melena 4
• Marked anemia 4

Diagnostic Tools

Diagnostic tools used to render a specific diagnosis include:

• Clinical assessment 5
• Upper endoscopy 2, 5
• Colonoscopy 2, 3, 5
• Scintigraphy 5
• Conventional arteriography 5
• Computed tomography angiography 5
• Magnetic resonance angiography 5