Fast Facts on Clinton's Operation

March 8, 2005 — -- Bill Clinton will be hospitalized on Thursday to remove fluid that has built up around his lungs. This procedure is not expected to present any significant risks to the former president.

In September of 2004, Clinton underwent quadruple bypass surgery.

As a result of that surgery, fluid and scar tissue has built up in the area surrounding his lungs.

Fluid buildup is following a coronary bypass operation is quite common and occurs in about 85 percent of patients.

Most cases of fluid buildup resolve on their own, but in some cases the fluid persists -- these cases require medical attention.

The majority of cases are treated by thoracentesis, a procedure that uses a needle inserted into the chest to remove fluid.

In Clinton's case, the fluid around the lungs appears to have become thick and fibrous, which means it cannot be removed with a needle.

The thick, fibrous nature of the fluid is putting pressure on his lung and is causing a partial lung collapse. This is sometimes known as "trapped lung."

Trapped lung occurs when the membrane surrounding the lungs becomes encased in a fibrous case or peel, preventing full expansion of the lung.

The procedure Clinton is scheduled to have is known as a decortication, the removal of part or all of the outer surface of an organ.

By removing the fibrous case or peel through decortication, the lung will be allowed to breathe fully again.

The procedure is done under general anesthesia.

Following the operation and several days of recovery, Clinton is expected to be fully active.

Sources: Chest: The Cardiopulmonary and Critical Care Journal;