Pulmonary tuberculosis: An observational study to compare radiographic abnormalities with reference to smear microscopy status

Abstract

Interpretation of Chest X Ray (CXR) in relation to sputum smear microscopy can be useful in early diagnosis of pulmonary TB. The study aimed to compare the CXR findings in pulmonary TB cases with positive sputum microscopy and negative sputum microscopy. Patients with presumptive pulmonary TB were grouped into smear positive pulmonary TB and smear negative pulmonary TB groups based on CXR and sputum smear microscopy. CXR findings in the two groups were compared using chi square and students- t test. A total of 225 patients with presumptive pulmonary TB were evaluated. Of these, 174 subjects were included in the study: 129 (74.2%) in smear positive pulmonary TB group and 45(25.8%) in smear negative pulmonary TB group. Parenchymal involvement was the most common finding in both smear positive and smear negative groups seen in 118 (91.5%) and 42 (93.3%) subjects, respectively. The area of parenchymal involvement was significantly more in smear positive group as compared to smear negative group (p<0.001). Cavitation was more commonly associated with smear positive group (p=0.005) Nodal enlargement was significantly more common among smear negative subjects (p<.001). CXR could detect 25.8% smear negative pulmonary TB cases. Extensive parenchymal infiltration and cavitation were more commonly associated with smear positive patients whereas nodal involvement was significantly more common in smear negative patients.