Thoracentesis | What Is Thoracentesis?

Thoracentesis is a surgical procedure in which a needle is inserted into the chest to drain air or fluid collected inside the pleural sacs, which envelop the lungs. It can be performed for diagnostic purposes, where the pleural cavity contents are examined to determine the disease that caused their accumulation.

It also has therapeutic purposes, such as relieving the pressure on the lungs and facilitating respiration.


Thora: From “thorax,” meaning the chest.

Centesis: To puncture a bodily structure to withdraw fluid.

Anatomical overview

The lungs are housed in the chest, extending from the root of the neck above to the diaphragm below. Each lung is covered by a “sac” called the pleural cavity, consisting of two layers with a thin film of fluid ordinarily present in between. During respiration: Each lung expands and repeatedly shrinks, with the pleural fluid allowing both layers of the pleura to slide on each other to permit lung expansibility, by lubricating their contacting surfaces.

Several diseases and injuries, which will be discussed below, can cause air or fluids to accumulate abnormally within the pleural space. Since the pleura is directly in contact with the lungs, this can compress the respiratory organs by applying direct pressure on them. In severe cases, the lung may collapse and occupy only a fraction of its allocated space within the chest when seen on X-Ray, with the enlarged pleura encroaching more and more upon the lung tissues. With its size reduced, the affected lung can no longer perform its function adequately.

The lungs and the pleural cavities are placed inside the rib cage, a sturdy, protective bony barrier consisting of twelve pairs of ribs, with the breastbone or sternum in the middle. It functions to protect the body’s most important organs from trauma: The lungs and the heart.

For a needle to be placed in the pleural space, the physician will need to insert it in the space between two ribs, often referred to as an “intercostal space.” You can palpate both the bones and the spaces between them by feeling them on your chest, especially in thin individuals, by applying gentle pressure with the fingers. The heart’s powerful thrusts can be detected while doing this.