Thoracentesis

Thoracentesis

Thoracentesis is a medical procedure used to take fluid or air out of the space around the lungs. Doctors do this to help diagnose or treat certain health problems. During the procedure, a thin tube, called a cannula, is carefully placed into the chest after a local numbing medicine is applied.

This procedure was first done by Morrill Wyman in 1850 and later described by Henry Ingersoll Bowditch in 1852. Today, doctors often use ultrasound to guide the procedure, which helps make it safer and reduces the chance of problems.

The exact spot where the tube is placed can vary, but it is usually in the area between the ribs on the side of the chest, depending on what the doctor recommends. This careful approach helps ensure the procedure is done safely and effectively.

Indications

This procedure is used when fluid builds up in the chest outside the lung without a clear reason. Looking at this fluid helps doctors learn what’s wrong. Removing the fluid can make the patient more comfortable and help the lung work better.

The most common reasons for fluid to collect in the chest are cancer, congestive heart failure, pneumonia, and recent surgery. In places where tuberculosis is common, it can also cause fluid to collect.

When the heart or lungs are struggling because of air (pneumothorax), fluid (pleural fluid), or blood (hemothorax) outside the lung, doctors usually use a different method called tube thoracostomy instead.

Contraindications

Sometimes, doctors might decide not to do a thoracentesis. This is a procedure to remove fluid from the chest area. They might choose not to do it if the patient is not cooperative or has certain health conditions that make the procedure risky.

For example, if there is a problem with blood clotting that can’t be fixed, doctors might not do the procedure.

Other reasons include if there is a certain lung condition at the spot where the procedure would be done, if the patient is using special breathing support machines, or if they only have one working lung.

Complications

When doctors do a thoracentesis, there can be some risks. Big risks include pneumothorax, hemopneumothorax, bleeding, low blood pressure, and fluid buildup in the lungs.

Smaller risks are that no fluid might come out, small bruises under the skin, feeling worried, shortness of breath, and coughing after a lot of fluid is removed. Using ultrasound to guide the needle can help lower these risks.

Follow-up imaging

Before, doctors often took a chest X-ray after the procedure to check for pneumothorax. But now, because ultrasound is commonly used, this may not be needed for people who are okay and not on a breathing machine.

Interpretation of pleural fluid analysis

Doctors can find out why fluid builds up around the lungs in several ways. First, they decide if the fluid is a transudate or an exudate. An exudate happens when fluid leaks from blood vessels into areas that are inflamed or damaged. This can come from infections, inflammation, cancer, or other issues. A transudate happens when fluid builds up because of problems like heart failure or kidney disease.

They also check the fluid for things like amylase, glucose, pH, triglycerides, and cholesterol. These tests can help find clues about conditions such as infections, cancer, or ruptures in the esophagus. Counting the cells in the fluid and testing for bacteria can also help doctors understand what might be causing the fluid to collect. Looking at the cells under a microscope can sometimes show if cancer is present.

Main article: Light's criteria

See also: Light's criteria

Amylase

A high amylase level in the pleural fluid can show problems such as pancreatitis, pseudocyst, cancer, or esophageal rupture.

Glucose

Glucose is low if the pleural fluid value is less than half of the normal serum value. This can be a sign of conditions like lupus, bacterial empyema, malignancy, tuberculosis, or esophageal rupture (Boerhaave syndrome).

pH

Normal pleural fluid pH is around 7.60. A pleural fluid pH below 7.30 can be a sign of the same problems that cause low pleural fluid glucose.

Triglyceride and cholesterol

Chylothorax (fluid from lymph vessels leaking into the pleural cavity) may be identified by checking triglyceride and cholesterol levels. High levels can show a chylous effusion. The main cause for chylothorax is rupture of the thoracic duct, often because of trauma or malignancy such as lymphoma.

Cell count and differential

The number of white blood cells can show if there is an infection. The amount of red blood cells can show if there is bleeding.

Cultures and stains

If the effusion is caused by infection, microbiological culture may find the organism causing the infection. A Gram stain may also help identify the organism. A Ziehl–Neelsen stain may identify tuberculosis or other mycobacterial diseases.

Cytology

Cytology helps identify effusions due to malignancy. The most common causes are lung cancer, metastasis from elsewhere, and pleural mesothelioma. Normal cytology results do not always rule out malignancy, but they make it less likely.