Diagnostic Accuracy of Sonographic Septations in Tuberculous and Malignant Pleural Effusions

Abstract

Background: Discrimination between tuberculous (TB) and malignant pleural effusions is a real practical challenge because both exist as exudative lymphocytic type. Transthoracic ultrasonography not only identifies and quantifies pleural effusion but also displays sonographic septations, which are frequently seen in TB pleural effusions and can help in differentiation between tuberculosis and malignancy successfully, without any invasive procedure. We designed this study to determine the diagnostic usefulness of these septations for tuberculous and malignant pleural effusions.
 Material and Methods: This prospective study was conducted in the OPD of Gulab Devi Chest Hospital Lahore, Pakistan, a 1500 bedded tertiary care hospital, from November 2016 to February 2018. Total of 339 consecutive cases, aged 14-83 years with radiological evidence of pleural effusion were included in the study. After detailed history, thorough physical examination, radiological, haematological and biochemical findings were recorded. Pleural fluid macroscopic, cytological, microbiologic and biochemical analysis results were also recorded. Ultrasonography was done, septated and non-septated pleural effusions identified and findings were noted. SPSS-16 was used for statistical evaluation. Fisher Exact test was utilized for comparison between TB and malignant cases with P-value < 0.05 taken as significant. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), diagnostic accuracy and positive likelihood ratio were calculated.
 Results: Out of total 339 cases, 49 (14.45%) were malignant and 290 (85.55%) were non-malignant. In the malignant group, only 03 cases (6.12%) showed sonographic septations. In the non-malignant group, 259/290 (89.31%) cases showed tuberculous etiology and 187/259 (72.20%) of these cases displayed sonographic septations. By considering septations as predictor of TB, statistical analysis revealed a sensitivity of 79.23%, specificity of 92.85%, PPV of 98.42%, NPV of 44.31% and diagnostic accuracy of 81.29%, respectively.
 Conclusions: Sonographic septations can be a valuable predictor of tuberculosis, in a population with high prevalence of the disease. We found it to be a useful feature in differentiating between a malignant and tuberculous etiology, in exudative lymphocytic pleural effusions. It can be used with confidence in patients who are unfit for interventional procedures.