TB of the lungs is usually detected in the chest radiograph (x-ray) and confirmed by sputum examinations. With a special staining method and microscopical examination of sputum it is possible to detect bacteria in the sputum. If TB grows in the culture it confirms the diagnosis. Sometimes it is necessary to perform a bronchoscopy or computed tomography (CT) of the lungs.
A small child swallows sputum and cannot produce samples like adults. Therefore a specimen for staining and culturing is obtained by gastric aspirate. This is performed in the hospital.
Various imaging techniques are used when examining TB in other sites than lungs. In addition, a sample of the tissue or pus from the body site where the disease is located is taken and examined.