Diagnosis of Tuberculosis: Specimen Collection

Authors: Madhukar Pai, MD, PhD—Author and Series Editor; Pamela Chedore, MLT—Co-author
Number of pages: 7
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Overview: A good diagnostic approach for TB requires collection of the right clinical specimen(s) of adequate quality and quantity. For pulmonary TB, sputum is the most important sample for laboratory testing. Although blood is a popular sample in the Indian private sector, there is no accurate blood test for active TB. For extra-pulmonary TB, it is critical to obtain specimens from the site of disease, and this usually includes collection of tissue (biopsy) and/or body cavity fluids from the suspected disease site. For childhood TB diagnosis, sputum can be collected from older children. In young children, fasting gastric aspirates are the routinely collected samples. For latent TB infection diagnosis, there are two main options – interferon- gamma release assays which require venous blood samples, or the tuberculin skin test (Mantoux), which is an intra-dermal skin test. In all the above situations, clear instructions on specimen collection should be provided to patients as well as to laboratories and clinics. Quality of specimens can often have a big impact on test results, and every effort should be made to ensure quality in specimen collection, transport and processing.

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Diagnosis of Tuberculosis: Importance of Appropriate Specimen Collection

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