Utilizing thoracic ultrasonography in determining the characteristics of pleural fluid: Development of a novel sonographic scoring system.

Background: To evaluate the utility of thoracic ultrasound imaging (USI) in assessing the nature of pleural fluid (PF) using a scoring system.

Methods: The files of patients who underwent thoracic USI and thoracentesis due to PF accumulation were retrospectively examined. PF sonographic patterns and pleural thicknesses were retrieved from the USI records. Based on the Light's criteria, PFs were classified into transudative PF (TPF) and exudative PF (EPF). A scoring system was established based on the sonographic patterns and pleural thickness. Sonographic scores and other clinical, radiological, and demographic characteristics of the two groups were comparatively analyzed.

Results: Among the 64 cases analyzed, 32 (50%) were categorized as TPF. The average pleural thickness in the TPF group was 1.4 mm. The hypoechoic sonographic pattern rate in the TPF group (75%) was significantly different from that in the EPF group (p < 0.001). A hypoechoic sonographic pattern (p = 0.002) and pleural thickness >1.5 mm (p = 0.031) were independent predictors of EPF. The scoring system demonstrated a sensitivity of 84.38% and a specificity of 75.00% for predicting EPF when the sonographic score was ≥3.

Conclusion: Thoracic USI can serve as a noninvasive method to predict the nature of PFs by combining sonographic patterns and pleural thickness.