DeepSite - 🧬 RemixLearn the step-by-step process for effectively eliminating tuberculosis as a diagnosis.
Tuberculosis (TB) is a potentially serious infectious disease that mainly affects the lungs. The bacteria that cause tuberculosis are spread from person to person through tiny droplets released into the air via coughs and sneezes.
Accurate diagnosis is crucial because TB treatment is lengthy and has significant side effects. Conversely, missing a TB diagnosis can have serious public health consequences.
TB remains one of the top 10 causes of death worldwide according to WHO.
Follow these steps systematically to evaluate for tuberculosis
Evaluate for signs and symptoms of TB including chronic cough (≥2 weeks), fever, night sweats, weight loss, and hemoptysis.
Assess for TB risk factors including:
Perform a tuberculin skin test (Mantoux) or interferon-gamma release assay (IGRA) to detect TB infection.
These tests cannot distinguish between latent and active TB. Negative tests don't completely rule out active TB.
Collect 3 sputum specimens (8-24 hours apart, at least one early morning specimen) for:
Obtain chest radiograph (CXR). Consider CT chest if high suspicion with negative CXR.
Look for upper lobe infiltrates, cavities, lymphadenopathy, miliary pattern, or pleural effusion.
For suspected extrapulmonary TB, consider:
Consider alternative diagnoses if all of the following are negative and clinical suspicion remains low:
TB can only be confidently ruled out after thorough evaluation in high-risk patients.
Understanding the different tests available for TB diagnosis
Direct visualization of acid-fast bacilli in sputum samples. Results typically available within 24 hours.
Sensitivity: 45-80%
Specificity: ~95%
Nucleic acid amplification test that detects TB DNA and rifampin resistance. Results in 2 hours.
Sensitivity: ~85% (smear+)
Specificity: ~98%
Growth of M. tuberculosis in liquid or solid media. Required for drug susceptibility testing.
Sensitivity: ~80%
Time: 2-6 weeks
Intradermal injection of purified protein derivative (PPD) measured after 48-72 hours.
Sensitivity: 60-80%
Specificity: 80-95%
Measures IFN-γ response to TB-specific antigens (ESAT-6, CFP-10). Doesn't cross-react with BCG.
Sensitivity: 80-90%
Specificity: ~95%
Classic findings include apical infiltrates, cavities, lymphadenopathy, or miliary pattern.
Cannot confirm diagnosis
Useful in screening
Visual representation of the diagnostic pathway
Signs, symptoms, risk factors
This algorithm provides a simplified view of TB diagnosis. Clinical judgment is always required, especially for high-risk patients.
Further reading and guidelines for TB diagnosis
Comprehensive global guidelines for TB diagnosis and treatment from the World Health Organization.
Visit ResourceDetailed diagnostic algorithms and treatment recommendations from the U.S. CDC.
Visit ResourceInteractive tools and calculators for TB diagnosis interpretation and risk assessment.
Visit ResourceSubscribe to our monthly newsletter for the latest in tuberculosis diagnosis and treatment.
We respect your privacy. Unsubscribe at any time.