Role of Chest Sonography in Evaluation of Pleurodesis in Patients With Malignant Pleural Effusion

Malignant pleural effusion (MPE) imposes a significant burden on patients and health-care providers. Most of the malignant pleural effusions are the result of metastases to the pleura from other sites. The primary tumors were, in the decreasing order of frequency: lung (37%), breast (17%), unknown site (10%), lymphoma (9%), gastrointestinal (8%), ovary (7%) and mesothelioma (3%) .

Management of malignant effusions depends on palliation of dyspnea and prevention of the re accumulation of pleural fluid to provide the highest possible quality of life, regardless of the need for other treatment modalities. Most patients require definitive treatment, usually drainage and chemical pleurodesis to relieve symptoms and prevent fluid recurrence. Pleurodesis is defined as the symphysis between the visceral and parietal pleural surfaces; its function is to prevent accumulation of either air or fluid into the pleural space. Effusions of malignant origin are the most common indication for pleurodesis Thoracic ultrasound (TUS) can easily visualize pleural effusions and help in identifying malignant effusion and the presence of pleural adhesions or thick pleural peel and could therefore have a role in predicting long-term pleurodesis success or failure in MPE.

One of the easiest sign to identify during chest sonography is the movement of the visceral pleura compared to immobility of the parietal pleura. This sign of 'pleural sliding', firstly described in veterinary medicine and was used to exclude the presence of pneumothorax when present and to suspect atelectasis, fibrosis or pleural adhesions (pleurodesis) when absent. Thoracic ultrasonography easily detects the sign of 'pleural sliding', due to the movement of the visceral pleura on the parietal pleura This sign is absent when pleurodesis is successful. Contrast-enhanced chest CT has become the imaging modality of choice to detect pleural effusions and assist the differentiation between benign andmalignant effusions detected bystandard radiographs. Chest CT findings characteristic of malignant pleural disease include (i) circumferential pleural thickening, (ii) nodular pleural thickening, (iii) parietal pleural thickening greater than 1 cm, and (iv) mediastinal pleural involvement or evidence of a primary tumour.(9'10) The reported specificities of each of these individual findings range from 22% to 56% and sensitivities range from 88% to 100%.(9;11) Histological confirmation of the diagnosis, however, remains necessary. Chest CT should be performed before large-volume thoracocentesis to allow visualization of both the visceral and parietal pleurae, which may identify a pleural mass and appropriate site for needle biopsy.