A hydrothorax is a medical condition wherein the pleural cavity, the space between the lungs and the chest, fills up with a pale, yellow and transparent fluid. This fluid is known as serous fluid, and normally serves the function of lubricating the lungs so they can move freely. The excess fluid causes the lungs to compress, and this leads to painful and difficult breathing, called dyspnea. This condition also leads to a lack of lung sounds when listening with a stethoscope, often the result of an underlying disorder.
There is a broader category, known as “pleural effusion”, of which a hydrothorax is one sub-category. Hydro means water and thorax means chest, so hydrothorax simply translates to “water in the chest.” The other categories include: hemothorax, blood in the chest; chylothorax, lymphatic fluid—chyme—in the chest; and pyothorax, also called empyema, which is pus in the chest. All of these terms refer to an excess of their particular fluid being in the chest, which is usually dangerous and indicative of an underlying disease or damage to the lungs.
The main cause of a hydrothorax is usually a problem with the liver known as cirrhosis. In cirrhosis of the liver, the liver function is decreased by scarring, nodule formation, and fibrosis, which are all the result of the liver repairing itself after the damage done by alcoholism, hepatitis B, and fatty-liver disease and other causes. It is unknown exactly how cirrhosis of the liver leads to hydrothorax, but it is believed that the malfunction of the liver causes an imbalance in the fluids of the body, and that excess can show up in the lungs.
Treating a hydrothorax presents several problems. The main difficulty is that most of the time, the hydrothorax is the result of the final stages of liver disease. It is not often recommended that the fluid be removed from the lung with a chest tube, as it will not stop the flow of excess fluid. The underlying cause has to be fixed, which usually means a liver transplant. Besides being risky, it is often difficult to find a donor for a liver transplant.
There is a another procedure, known as a transjugular intrahepatic portosystemic shunt (TIPS), that can be performed to fix a hydrothorax and is safer than a transplant. A TIPS procedure entails creating a passageway, or shunt, from the two main veins of the liver that bypass the scarring and allows the blood to flow smoothly through the liver. This reduces the overall pressure and lessens fluid build-up. Although it reduces the root of the problem, there is a danger that the liver itself will be damaged by the TIPS procedure.