Fluid around the lung (pleural effusion) is a potentially dangerous condition that can masquerade as something less worrisome. What may seem like chest pain or coughing due to a bad cold could actually have serious health ramifications. It’s not that rare, either. More than 1.5 million people are diagnosed with pleural effusion in the United States each year.

Pleural effusion occurs when fluid builds up in the space between the lung and the chest wall. This can happen for many different reasons, including pneumonia or complications from heart, liver, or kidney disease. Another reason could be as a side effect from cancer. “One of the most common reasons pleural effusion develops is due to congestive heart failure,” says Jonathan Puchalski, MD, a pulmonologist at Yale Medicine.

The symptoms of pleural effusion can range from none to shortness of breath to coughing, among others. The greater the build-up of fluid, the more likely symptoms will be noticeable. 

In addition to excess fluid, the tissue around the lung may become inflamed, which can cause chest pain. In extreme cases, a person can have up to four liters of excess fluid in the chest. It's very uncomfortable. “Imagine trying to breathe with two soda bottles pushed up against your lungs,” Dr. Puchalski says.

A physician will usually diagnosis pleural effusion based on interviewing the patient about symptoms and a physical examination. To confirm a diagnosis, he or she may also request an imaging test, which could be a chest X-ray, ultrasound, or computed tomography (CT) scan. To further help with diagnosis, a doctor may extract a sample of the excess fluid to be tested to determine the cause. 

The best way is to treat the cause of the effusion. If the cause is pneumonia, a doctor will likely prescribe antibiotics to treat the infection, which may also cause the fluid to go away. If fluid build-up has been caused by congestive heart failure, a physician will likely prescribe diuretics, such as Lasix, for treatment. 

For large pleural effusions, or for those with an unknown cause, the fluid will need to be drained through a procedure called thoracentesis. This involves inserting a needle in the space between the lung and the chest wall and draining the liquid. In these cases, a doctor may also send a sample of fluid to be tested for other causes, such as lung cancer, for example. Some patients may require a pleural drain that is inserted through the skin so that the buildup of fluid can be drained repeatedly without the need for repeated thoracentesis.

“My patients always want to know if it will come back,” says Dr. Puchalski. “Sometimes it does and sometimes it doesn’t.” He explains that the risk of recurrence is based mostly on the cause of the pleural effusion in the first place. For lung cancer patients, he explains, the buildup is likely to occur again.

At Yale Medicine, patients receive care from a team of physicians who specialize in dealing with pleural effusions. The clinical care team includes a physician assistant and an advanced practice registered nurse who are trained in this subspecialty. What makes Yale especially unique, Dr. Puchalski adds, is our ability to perform bilateral thoracenteses. This means that a patient can have fluid build-up removed from both lung areas in a single treatment, rather than scheduling two separate procedures. Patients can do this at Yale Medicine, Dr. Puchalski explains, due to a highly-trained staff. 

Another unique aspect of care at Yale Medicine is that doctors rarely ask patients to stop taking blood-thinning medication before the procedure. Many other medical centers require that patients stop blood thinners one week before the procedure, Dr. Puchalski says. However, Yale researchers conducted thorough research and found that this precaution did not affect the final outcome of the procedure. “We don’t make patients wait to undergo the procedure,” he says.