Pleural Effusions

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What are Fetal Pleural Effusions?

A pleural effusion is an accumulation of fluid around the lungs. Pleural effusions can be isolated (primary hydrothorax, also called called chylothorax) or secondary to other conditions such as bronchopulmonary sequestrations, congenital diaphragmatic hernia, cardiac anomalies, fetal infections, metabolic disorders, chromosomal or syndromal disorders. Pleural effusions can be seen on ultrasound as a black rim of fluid in the fetal chest. Sometimes, pleural effusions can be a sign of fetal heart failure. They are then associated with fluid in the fetal abdomen (ascites), fluid around the heart (pericardial effusion) and fluid under the skin. When fluid effusions are present in multiple compartments in the setting of heart failure, this is called ‘hydrops’.

What is the outcome for fetuses with Pleural Effusions?

Mild to moderate primary hydrothorax, which does not lead to heart failure, displacement of the heart or severe lung compression has good outcomes when managed conservatively and the outlook for a normal life is excellent.

Severe pleural effusions however lead to increased pressure in the chest, thereby impacting lung development and heart function. Severe effusions can sometimes lead to heart failure and hydrops. Without prenatal treatment, these fetuses will only survive in 25% of cases.

What other tests should be considered?

Every fetus with suspected pleural effusions, needs to be referred to a specialized perinatal center such as the Fetal Medicine Unit at Mount Sinai Hospital. A detailed ultrasound will be performed to determine the extent and the cause of the pleural effusion. Sometimes, a detailed heart ultrasound (echocardiogram) will be required. Further investigations include maternal blood work to determine the cause of the effusion and in certain circumstances amniocentesis will be performed to determine the fetal karyotype and to exclude fetal infections.

Ongoing ultrasounds are used to monitor the severity of the effusion and to look for signs of heart failure.

What therapy is available?

Fetuses with mild hydrothorax do not require any prenatal therapy. After birth, the infant will be assessed by a neonatologist (doctor specialized in newborn care). Sometimes the effusion may need to be drained after birth by use of a special catheter (chest tube) and babies may be fed with a special formula to prevent re-accumulation of the fluid.

Fetuses with moderate and severe hydrothorax benefit from antenatal drainage of the effusion. Such drainage can be achieved by (repeated) thoracocentesis, but the effusion usually re-accumulates within a couple of days. When earlier in pregnancy, insertion of a chest shunt may therefore be the preferred option. Shunt migration or obstruction leads to the need for repeated procedures in 10-20% of cases. The average gestational age at delivery after chest shunt insertion is 34 to 35 weeks. Neonatal survival after chest shunt insertion is 55% in hydropic fetuses and 85% in non-hydropic fetuses. Care after birth is similar to what is described above for infants with mild hydrothorax.

Special Pregnancy Program

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Fetal Medicine: 416-586-4800 x 7756
Fax: 416-586-3216

Maternal Medicine: 416-586-4800 x 7000
Fax: 416-586-5109

Main clinic hours: Monday to Friday, 8am to 4pm

Prenatal Diagnosis & Medical Genetics

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phone: 416-586-4800 x 4523
fax numbers:
416-586-4723 or 416-586-8384

Perinatal Mental Health

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Phone: 416-586-4800 x 8325
Fax: 416-586-8596