The risks of thoracentesis usually are minor. They include:
- Pneumothorax. This is a condition in which air collects in the pleural space (the space between the lungs and chest wall). Sometimes air comes in through the needle, or the needle makes a hole in the lung. Usually, a hole will seal itself. If enough air gets into the pleural space, however, the lung can collapse. Your doctor may need to put a tube in your chest to remove the air and let the lung expand again.
- Pain, bleeding, bruising, or infection where the needle or tube was inserted. Although rare, bleeding can occur in or around the lungs. Your doctor may need to put a tube in your chest to drain the blood. Sometimes surgery is needed to treat the bleeding.
- Liver or spleen injuries. These complications are very rare.
Your doctor may do a chest x ray after the procedure to check for lung problems.