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…
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…
Epidemiology & Clinical Spectrum Irritable bowel syndrome (IBS) affects ~10–15% of the global population, with a 2:1 female-to-male predominance. It is classified into subtypes based on stool morphology (Bristol Stool…
