To demonstrated the efficacy and safety of taking biopsy specimens from parietal pleura in undiagnosed exudative pleural effusion

Pleural effusions are either transudate or exudate according to the biochemical analysis of aspirated pleural fluid. Thoracentesis or blind pleural biopsy may not provide a definitive diagnosis. Cryobiopsy has more successful diagnostic results than forceps biopsies with complications (only hemorrhage) during procedures. Cryobiopsy can obtain more diagnostic biopsies due to the size of the biopsies and best property in expressions of an artifact-free sample area

Inclusion Criteria:

• patients diagnosed as exudative pleural effusion according to Light criteria .informed written consents were taken from all patients enrolled in the study

Exclusion Criteria:

• patients who refused participation ,patients unfit for medical thoracoscopy (MT) will be excluded from the study such as:Uncooperative patient ,Severe uncorrected hypoxemia in spite of continuous oxygen administration, because it's necessary to keep oxygen saturation above 90 % during procedure ,patients who could not tolerate the lateral decubitus position for a period long adequate to do the thoracoscopy, unstable cardiovascular or hemodynamic condition, uncorrected Coagulation defects and small pleural space