[Nosology and epidemiology of gastrointestinal bleeding]

Gastrointestinal bleeding (GIB) is a frequent and potentially life-threatening emergency. It is defined as any bleeding originating from the digestive tract, either overt (hematemesis, hematochezia, melena) or occult. From a nosological perspective, GIB is classified into upper GIB (proximal to the Treitz ligament), lower GIB (colonic or anorectal origin), suspected small bowel bleeding (SSBB), mid-GIB (jejunal or ileal lesions), and obscure GIB (no source identified despite complete evaluation). Over the past 20 years, the incidence of upper GIB has declined by 30-50%, mainly due to Helicobacter pylori eradication, proton pump inhibitors use, and reduced tobacco consumption. Conversely, lower GIB is increasing, and in some countries has surpassed upper GIB in frequency. Hospital mortality has decreased from about 10% to 5-7% owing to advances in diagnostics, therapeutic endoscopy, and healthcare organization. Cirrhotic patients and the elderly remain at particularly high risk.