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 & Classification A hiatal hernia (HH) is defined as an abnormal protrusion of abdominal viscera—most commonly gastric tissue—through the esophageal hiatus of the diaphragm into the posterior mediastinum.…
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,…
Authored with input from current guidelines: American Society of Colon and Rectal Surgeons (ASCRS) 2022, European Association of Endoscopic Surgery (EAES)/European Society of Gastrointestinal Endoscopy (ESGE) 2020, National Institute for…
Definition and Pathophysiology Fecal impaction is a severe manifestation of chronic constipation characterized by the accumulation of hardened, dehydrated fecal matter in the rectum (rectal impaction) or proximal colon (colonic…
Epidemiology & Clinical Relevance Anal fissures represent one of the most common causes of anorectal pain and hematochezia, affecting approximately 1 in 10 individuals at some point in life, with…
