136. Gastrointestinal bleeding - classification, etiology, pathogenesis, clinical manifestations.

Gastrointestinal bleeding- classification, etiology, pathogenesis, and clinical manifestations.

GI bleeding is bleeding that occurs anywhere along the gastrointestinal tract, from the esophagus to the rectum. It can be acute or chronic and may present as overt or occult bleeding.

Classification

1. 1 By anatomical source

1. 2 By presentation

Etiology

Upper GI bleeding (more common)

• Peptic ulcer disease (gastric or duodenal ulcer).
• Esophageal varices (portal hypertension).
• Mallory-Weiss tear (mucosal laceration from forceful vomiting).
• Gastritis or erosive esophagitis.
• Gastric cancer.

Lower GI bleeding

• Diverticulosis (most common in elderly).
• Colorectal cancer or polyps.
• Inflammatory bowel disease (ulcerative colitis, Crohn's).
• Angiodysplasia.
• Hemorrhoids, anal fissures.

Pathogenesis

Upper GI bleeding

1. Mucosal injury or erosion (e.g., NSAID-induced ulceration) → vessel exposure → bleeding.
2. Portal hypertension → variceal dilatation → rupture.
3. Severe vomiting → mucosal tear at gastroesophageal junction (Mallory-Weiss).

Lower GI bleeding

1. Vascular fragility or angiodysplasia → spontaneous bleeding.
2. Diverticula → damage to adjacent vessels.
3. Inflammatory or neoplastic erosion → vessel disruption.

Clinical manifestations

Upper GI bleeding

• Hematemesis: vomiting of fresh red blood (active severe bleed) or "coffee-ground" material (partially digested blood).
• Melena: black, tarry, foul- smelling stools (digested blood from upper source).
• Signs of anemia: pallor, fatigue, weakness.

Lower GI bleeding

• Hematochezia: bright red or maroon blood per rectum (usually lower source

but can occur in massive UGIB).

• Occult blood loss: iron deficiency anemia, positive fecal occult blood tests.

Severe acute bleeding (any source)

• Hypovolemia → hypotension, tachycardia.
• Dizziness, syncope.
• Shock (in massive hemorrhage ).