The most notable potential complication after thoracentesis is the developmnent of a pneumothorax. Fortunately, even when present, these rarely require the placement of a chest tube. If you suspect a pneumothorax, obtain a chest x-ray (CXR). CXRs are not routinely required after an uncomplicated thoracentesis, but should be obtained if:

• air was aspirated from the pleural space during the procedure
• the patient develops chest pain,dyspnea, or hypoxemia during or after the procedure
• multiple needle insertions were required
• the patient is critically ill
• the patient is being mechanically ventilated

Other complications of thoracentesis include pain, coughing, localized infection, hemothorax, intraabdominal-organ injury, air embolism, and post-expansion pulmonary edema. Post-expansion pulmonary edema is rare and can most likely be avoided by limiting therapeutic aspirations to less than 1500mL. To avoid complications, adhere to the following:

1. Understand how to use all equipment, especially the 3-way stopcock. Improper use of the stopcock may lead to pneumothorax
2. Firmly establish the level of the effusion with your clinical exam prior to initiating the procedure.  If this is not possible, the procedure should be performed with ultrasound guidance
3. Check for coagulopathy or thrombocytopenia
4. Always advance the needle along the superior aspect of the rib to avoid intercostal vessel and nerve injury
5. Limit therapeutic drainage to 1500mL to avoid post-expansion pulmonary edema
6. Always remove the needle when the patient is at end expiration. Negative intrathoracic pressure generated during inspiration may lead to pneumothorax