The most common problem that occurs from Thoracentesis is for more air to get into the area around the lung, causing the lung to collapse.  This happens 5% to 20% of the time.  Most often the collapsed lung gets better on its own, but sometimes a tube has to be put in to get the air out.  This tube would stay in for several days.  You would have to remain in the hospital.

You may feel short of breath immediately after the procedure, but this should get better.  Very rarely, the needle goes through an organ, causing bleeding.  Sometimes the needle can cause an infection.  The goal of Thoracentesis is to gain important information and to make you feel better, but there is always a chance it will make you worse.