1. To evaluate the diagnostic yield and safety of thoracoscopic pleural lavage and pleural brushing in cases of undiagnosed exudative pleural effusion.

The diagnosis of etiology of pleural effusions remains a challenging issue even after diagnostic thoracocentesis and closed pleural biopsy in significant number of cases. In order to get a pleural biopsy or the diagnosis of undiagnosed pleural effusion, several techniques were used, such as percutaneous needle pleural biopsy, CT guided pleural biopsy, medical thoracoscopy, video-assisted thoracoscopy and open thoracotomy.

Medical thoracoscopy plays a huge role with a great diagnostic yield in the diagnosis of exudative pleural effusion. Pleural biopsy is considered to be a gold standard investigation of choice in patients with undiagnosed exudative pleural effusions. It can be used to describe the diagnostic and therapeutic exploration of the pleural space mostly under local anesthesia with or without conscious sedation, unlike video-assisted thoracoscopic surgery (VATS), which is conducted under general anesthesia with single lung ventilation.

Pleural biopsy with forceps is the usual mode of obtaining thoracoscopic specimens from suspected pleural lesions. However, this may be associated with complications like bleeding that hinders further biopsy, additionally, the decision to take biopsy could be difficult, especially when the targeted lesions are on the visceral pleura or near the vessels.

On the other hand, pleural brush could be used to safely obtain pleural specimens through medical thoracoscopy from suspected areas either in the parietal, visceral pleura or near the vascular structure.

The use of pleural lavage performed by injecting normal saline to pleural space and aspirated at the time of thoracoscopy would provide a higher diagnostic yield than the cytologic analysis of the fluid obtained at thoracentesis and could provide additional diagnostic information to thoracoscopic biopsy. This finding could be explained by one of the following:

1. The cells in the lavage are fresher and have not undergone degeneration as have many cells in the pleural fluid.
2. The lavage procedure could dislodge cells that would not have been detached otherwise. Tumor cells seeded in the subserous layer are exfoliated into the pleural cavity, and lavage could lead to the recovery of malignant cells.
3. Biopsies of the parietal and visceral pleura could have exposed the tumor and allowed malignant cells to be shed into the lavage fluid.

Inclusion Criteria:

• Patients will have documented exudative pleural effusion in whom the initial pleural tapping and closed pleural biopsy (CPB) will not be conclusive
• strong clinical and radiological data suggestive for alternative pathological diagnosis
• who will be admitted to our department

Exclusion Criteria:

• Patients with excess rib crowding with narrow inter-costal space and loculated pleural effusion cannot undergo thoracoscopy
• Patients with bleeding diathesis
• hemodynamic instability
• Arrhythmias
• intractable cough cannot be eligible to do thoracoscopy