What is fetal hydrothorax?

When abnormal amounts of fluid form within the chest of a fetus it is called fetal hydrothorax. This fluid may be in the space between the lungs and the chest wall (pleural space) or within the core of the lung or chest masses. Fetal hydrothorax may also be referred to as a pleural effusion. Because the chest is an enclosed space, the presence of fluid can compress the lungs and even displace the heart.
 
Compression of the lungs can interfere with their normal development in the womb. When this occurs, the lungs may not allow oxygen intake at the normal level (pulmonary hypoplasia). If fetal hydrothorax causes the heart to move it is called a mediastinal shift. When this happens a fetus has trouble receiving and pumping blood and may develop heart failure. When fetal hydrothorax worsens to cause fluid accumulation in other parts of the fetal body, it is called fetal hydrops.

Fetal Hydrothorax Diagnosis

Fetal hydrothorax may be detected during a routine ultrasound. If suspected, your doctor may refer you to a maternal-fetal medicine specialist who can perform a more thorough, detailed ultrasound examination. A maternal-fetal medicine specialist will also perform a test known as fetal echocardiogram. This test will allow him/her to determine the severity of the illness and the condition of the heart.

Fetal Hydrothorax Treatment

If a case of fetal hydrothorax is linked to fetal lung failure or fetal cardiac dysfunction, doctors may recommend one of the following prenatal intervention procedures:

• Fetal thoracentesis: In this procedure, doctors, under the guidance of ultrasound, insert a small needle into the chest of the fetus and drain the fluid. During thoracentesis, doctors are also able to obtain amniotic fluid, which can be tested along with the chest fluid, for underlying conditions that may have led to fetal hydrothorax. In up to 10 percent of patients, this procedure completely resolves fetal hydrothorax. However, many patients experience a recurrence of fluid buildup. For these patients, repeat thoracentesis is not a viable alternative, as it will not be able to prevent underdeveloped lungs.

• Thoracoamniotic shunting: For this procedure, doctors insert a small plastic tube (pigtail catheter) into the fetal chest. This allows the fluid to drain into the amniotic cavity in the uterus. This treatment provides relief of hydrothorax, continuous decompression of the fetal chest and offers the best chance to prevent underdeveloped lungs.