Table 3 Sonographic findings in patients with malignant and benign pleural effusions
Sonographic findingMalignant disease(n = 33)Benign disease(n = 19)p value (Fisherexact χ2)
Parietal pleural thickening1650.090
    >1 cm1410.004
    <1 cm240.175
Visceral pleural thickening/nodularity500.145
Diaphragmatic thickening1940.019
Diaphragmatic nodules1000.009
Size of effusion
Nature of effusion
Liver metastases*200.527
Overall TUS diagnostic rate†26/3319/19N/A
Sensitivity 79%Specificity 100%
NPV = 73%PPV = 100%
  • NPV, negative predictive value; PPV, positive predictive value; TUS, thoracic ultrasound.

  • *Liver metastases were the sole abnormality detected in one patient on TUS.

  • †Diagnostic rate of TUS based on the criteria mentioned in the Methods section (ie, diaphragmatic and parietal pleural nodule or nodules, pleural thickening >1 cm or hepatic metastasis).