Homocystinuria (HCU) is a rare autosomal recessive inherited metabolic disorder most commonly caused by cystathionine β-synthase (CBS) deficiency, leading to markedly elevated plasma homocysteine (…

Retropharyngeal abscess (RPA) is a potentially life-threatening deep neck space infection occurring in the space between the posterior pharyngeal wall and the prevertebral fascia. It predominantly…

Spinal epidural abscess (SEA) is a suppurative infection of the epidural space — a high-risk, low-prevalence infectious disease emergency with up to 90% of patients misdiagnosed on their first ED v…

Aneurysmal subarachnoid hemorrhage is a neurosurgical emergency caused by rupture of an intracranial aneurysm (85% of spontaneous SAH), with a mortality rate of ~50% and mean age of onset in the mi…

Galactosemia is an autosomal recessive inborn error of galactose metabolism, most commonly caused by deficiency of galactose-1-phosphate uridyltransferase (GALT) (classic galactosemia, Type I). It…

Myocarditis is an inflammatory disease of the myocardium caused by infectious or noninfectious etiologies, presenting classically with chest pain, arrhythmia, and/or heart failure/cardiogenic shock…

Acute severe MR is a medical emergency caused by sudden disruption of the mitral valve apparatus, most commonly from chordal rupture (myxomatous disease), papillary muscle rupture (post-MI), or inf…

Placental abruption is the premature partial or complete separation of a normally implanted placenta from the uterine decidua, complicating 0.6%–1.2% of pregnancies and representing a leading cause…

Clavicle fractures account for 2.6–4% of all fractures and are among the most common injuries seen in the ED, most frequently affecting males younger than 30 years. [1-2] The majority (~80%) involv…

Pompe disease is a rare autosomal recessive lysosomal storage disorder caused by deficiency of the enzyme acid alpha-glucosidase (GAA), leading to pathological glycogen accumulation in skeletal, ca…

Rib fractures are among the most common injuries from blunt thoracic trauma, occurring in up to 40% of trauma patients, with an overall mortality of approximately 10%. [1] Morbidity and mortality p…

An acute asthma exacerbation is a deterioration in baseline symptoms or lung function requiring a change in treatment, ranging from mild episodes manageable with rescue therapy to life-threatening…

Posterior epistaxis accounts for 10–20% of all epistaxis cases, arising from branches of the sphenopalatine and ascending pharyngeal arteries. It is more profuse, harder to control, and carries a g…

Sarcoidosis exacerbation refers to acute worsening of a known sarcoidosis diagnosis, most commonly presenting with increased cough, dyspnea, chest pain, and fatigue. In patients with advanced pulmo…

Budd-Chiari syndrome (BCS) is a rare condition characterized by thrombotic obstruction of the hepatic venous outflow tract, from the small intrahepatic venules to the hepatic vein–IVC junction, res…

Vasovagal syncope is the most common cause of syncope across all age groups, accounting for approximately two-thirds of syncope diagnoses, and is mediated by a reflex causing inappropriate vasodila…

Hypocalcemia is defined as a serum calcium level <8.5 mg/dL (2.12 mmol/L) or ionized calcium <4.8 mg/dL (1.20 mmol/L). It ranges from asymptomatic to life-threatening and requires a systematic appr…

Pulmonary contusion is the most common parenchymal injury in blunt chest trauma, occurring in 30–75% of cases, defined by alveolar hemorrhage and parenchymal destruction. [1-2] Symptoms typically m…

Animal bites account for approximately 1% of all ED visits in the United States (~1.5 million annually), with dogs responsible for the majority, followed by cats and then humans. [1-2] The followin…

Chilblains (pernio) is an uncommon, self-limited inflammatory condition of the acral skin caused by an abnormal vasospastic response to nonfreezing cold and damp exposure, presenting as erythematou…

Preeclampsia is a progressive, multi-organ hypertensive disorder of pregnancy occurring after 20 weeks' gestation, defined by new-onset hypertension (SBP ≥140 or DBP ≥90 mm Hg) with proteinuria or…

Second-degree AV block Mobitz type I (Wenckebach) is a typically benign conduction disturbance at the level of the AV node, characterized by progressive PR prolongation before a dropped QRS complex…

Localised tetanus is a rare form of tetanus in which muscle spasms and rigidity are confined to the area near the site of injury, usually a single limb.[1-2] It is more common in individuals with p…

Neonatal sepsis is a life-threatening systemic infection occurring within the first 28 days of life, classified as early-onset sepsis (EOS, ≤72 hours) or late-onset sepsis (LOS, >72 hours), with di…