Thoracentesis
Once the presence of an excess fluid in the pleural cavity, or pleural effusion, is suspected and location of fluid is confirmed, a sample of fluid can be removed for testing. The procedure to remove fluid in the chest is called a diagnostic thoracentesis. The doctor inserts a small needle or a thin, hollow, plastic tube in the chest wall and withdraws fluid.Thoracentesis can be done in the doctors office or at the hospital. Ultrasound is used to guide the needle to the fluid that is trapped in small pockets around the lungs. Thoracentesis usually does not cause serious complications. Generally, a chest x-ray is done after the procedure to evaluate the lungs. Possible complications of thoracentesis include the following:

Bleeding and bruising where the needle went in. In rare cases, bleeding may occur in or around the lung. The doctor can use a chest tube to drain the blood. In some cases, surgery is needed. Infection where the needle went in
Injury to the liver or spleen (in rare cases)
Pain. Pneumothorax, or buildup of air in the pleural space, with a collapsed or partially collapsed lung. Sometimes air comes in through the needle or the needle makes a hole in the lung. Usually, a hole seals itself—but sometimes air builds up around the lung and makes it collapse. A chest tube removes the air and lets the lung expand again.The lung fluid is examined under a microscope and is evaluated for the presence of chemicals and for its color and texture.
Medical use
In the late twentieth century, oral cholera vaccines started to be used on a massive scale, with millions of vaccinations taking place, as a tool to control cholera outbreaks in addition to the traditional interventions of improving safe water supplies, sanitation, handwashing and other means of improving hygiene. The Dukoral monovalent vaccine from Sweden, which combines formalin, heat-killed whole cells of Vibrio cholerae O1 and a recombinant cholera toxin B subunit, was licensed in 1991, mainly for travellers. Out of a million doses sold during the following decade, 63 negative side effects were reported. The Shanchol/mORCVAX bivalent vaccine, which combines the O1 and O139 serogroups, was originally licensed in Vietnam in 1997 and given in 20 million doses to children in Vietnam during the following decade. As of 2010, Vietnam continued to incorporate oral cholera vaccination in its public health programme, administering the vaccination through targeted mass vaccination of school-aged children in cholera endemic regions.The cholera vaccine is widely used by backpackers and persons visiting locations where there is a high risk of cholera infection. However, since it does not provide 100 percent immunity from the disease, food hygiene precautions are also recommended when visiting an area where there is a high risk of becoming infected with cholera. Although the protection observed has been described as "moderate", herd immunity can multiply the effectiveness of vaccination. Dukoral has been licensed for children two years of age and older, Shanchol for children one year of age and older.