Pathophysiology & Diagnostic Criteria Achalasia is a primary esophageal motility disorder rooted in neurodegenerative loss of inhibitory neurons (primarily nitric oxide– and VIP-producing) in the myenteric plexus of the lower…
Pathophysiology & Clinical Context Acute cholangitis is an acute bacterial infection of the biliary tree secondary to biliary obstruction (most commonly choledocholithiasis), leading to stasis, ascending infection, and systemic inflammation.…
Definition & Pathophysiology Acute pancreatitis (AP) is an acute inflammatory process of the pancreas, characterized by autodigestion of pancreatic tissue due to premature activation of pancreatic enzymes (e.g., trypsinogen →…
Pathophysiology Overview Chronic pancreatitis (CP) is a progressive, irreversible inflammatory pancreatic disorder characterized histopathologically by: Fibrotic replacement of parenchyma Calcification (in ~75% of alcoholic CP) Ductal distortion (strictures, dilatation, stones)…
Definition & Pathophysiology GERD is a chronic, often relapsing disorder characterized by the reflux of gastric (and duodenal) contents—acid, bile, pepsin, and pancreatic enzymes—into the esophagus, pharynx, or larynx, resulting…
I. Definition & Pathophysiology Peptic ulcer disease (PUD) is characterized by localized defects in the gastroduodenal mucosa that extend through the muscularis mucosae, resulting from an imbalance between aggressive factors…
I. Definition & Epidemiologic Context Splenomegaly is defined as a spleen that exceeds the 95th percentile for age- and sex-matched controls—typically: Transverse diameter >12 cm in adolescents Length >7.3 cm +…
Epidemiology and Pathophysiology Insulinomas are rare, typically benign (85–90%), functioning pancreatic neuroendocrine tumors (pNETs) arising from β-cells of the islets of Langerhans. Incidence is ~1–2 cases per million person-years, with…
Epidemiology and Burden of Disease Hepatitis A virus (HAV), a non-enveloped, positive-sense single-stranded RNA virus belonging to the Picornaviridae family (genus Orthohepatovirus), remains one of the most prevalent causes of…
Epidemiology and Global Burden Hepatitis E virus (HEV), a non-enveloped, positive-sense, single-stranded RNA virus belonging to the Hepeviridae family (genus Orthohepevirus, species HEV-A), is a globally significant cause of acute…
Authored for clinicians with emphasis on evidence-based practice, updated guidelines (AASLD 2018, EASL 2017/2024 updates), and practical decision-making tools. Epidemiology & Virology Primer (Clinician Refresher) HBV is a Hepadnaviridae family,…
Epidemiology and Clinical Significance Chronic functional constipation (CFC) affects approximately 12–27% of the general adult population, with prevalence rising sharply with age—up to 30–40% in individuals ≥65 years. It is…
Epidemiology & Pathogenesis Giardia lamblia (syn. G. duodenalis, G. intestinalis) is a flagellated protozoan parasite and a leading cause of protozoal gastroenteritis worldwide. The CDC estimates over 280 million cases…
Definition and Pathophysiology Lactose intolerance (LI) is a clinical syndrome characterized by the development of digestive symptoms following ingestion of lactose—the primary carbohydrate in mammalian milk. It results from lactose…
Definition and Disease Spectrum Microscopic colitis (MC) is a chronic, immune-mediated inflammatory disorder of the colon characterized by persistent, non-bloody, watery diarrhea, with normal-appearing mucosa on endoscopy but distinctive histopathological…
