Diagnosis	Red flags	Physical examination findings	Imaging findings	Special tests and calculations
Aortic dissection	Tearing sensation, pain radiates to back/abdomen, most severe at onset	Blood pressure/radial pulse discrepancy, aortic murmur, possible cardiac tamponade	CTA with obvious defect, CXR only sensitive with intrathoracic catastrophe	d-dimer often elevated
Malignant pleural effusion	History of malignancy, night sweats, older age, tobacco use, weight loss	Locally decreased breath sounds	CXR with unilateral or bilateral effusions	Apply Light criteria to thoracentesis fluid, pleural fluid cytology
Myocardial infarction	Angina, headache, arm/neck pain, nausea/vomiting	Diaphoresis, hypotension, third heart sound	CXR often normal	ECG with ST elevation in contiguous leads, abnormal cardiac enzyme studies
Pericarditis	Recent or current viral infection, prior pericarditis	Diffuse concave upward ST segments, PR segment depression without T wave inversion, positional chest pain	Possible cardiomegaly	ECG with diffuse ST elevation
Pneumonia	Fever, productive sputum, dyspnea	Egophony, leukocytosis, rhonchi, pleural rub	CXR or CT with consolidation	—
Pneumothorax	Acute onset dyspnea	Decreased breath sounds locally, hypotension, hypoxia, possible tracheal deviation, hyperresonance	Abnormal CXR indicating air in pleural space	Tension pneumothorax is often a clinical diagnosis before imaging
Pulmonary embolus	Acute onset dyspnea, history of deep venous thrombosis, history of malignancy, unilateral leg swelling	Hypotension, hypoxia, sinus tachycardia, respiratory distress	CXR with abrupt hilar cutoff, oligemia, or pulmonary infarction Filling defect often detectable with CTA	Dedicated clinical decision algorithm, d-dimer, hypoxia with alveolar-arterial gradient, ECG with right heart strain
Tuberculosis	Exposure to tuberculosis, hemoptysis, fever, night sweats, weight loss	Egophony, leukocytosis, pleural rub, rhonchi	Often consolidation, lymphadenopathy, and/or unilateral pleural effusion; cavitation common	Acid-fast bacilli Gram stain, sputum culture, purified protein derivative