What is the most definitive method to diagnose pneumothorax?

The most definitive method to diagnose pneumothorax is through a CT scan. This imaging technique offers high sensitivity and specificity, allowing for the clear visualization of pleural air and even small pneumothoraces that might not be easily detectable on other imaging modalities. While chest X-rays are commonly used as a first-line imaging tool for pneumothorax and can be quite effective, especially in larger cases, they may sometimes miss smaller pneumothoraces or may have misinterpretation due to the angles of the images taken.

Ultrasound can also be helpful, particularly in emergency settings, as it can show pleural sliding and the presence of air in the pleural space, but it is not as definitive as CT scans. A Complete Blood Count, on the other hand, does not provide any direct information about the presence of pneumothorax or the state of the pleural space; it is rather used to evaluate components such as red blood cells, white blood cells, and platelets, which are important in different clinical scenarios. Therefore, while chest X-rays are highly utilized for initial evaluation, the CT scan stands out as the most definitive method for diagnosing pneumothorax due to its detailed imaging capabilities.