Thoracentesis is a relatively common procedure in pulmonology. Thoracentesis is only performed when the patient has a pleural effusion and aims at one or both of these two goals: (1) Remove and analyse the pleura fluid to determine the cause of pleural effusion (2) Drain the excess fluid to help the patient breathe easier when they have trouble breathing. The procedure is very safe, easily performed, quick and could be guided by CT scan images.