Massive pericardial effusion in an early gestational fetus having intrapericardial diaphragmatic hernia

Intrapericardial diaphragmatic hernia is a very rare phenotype of congenital diaphragmatic hernia. Twelve cases of this condition have been reported under the age of 1 year since 1981, and in only four cases were abnormal findings observed antenatally. We report a case of a fetus with this disease in which pericardial effusion was noted in an earlier gestational age than any other previously reported cases. A 35-year-old pregnant woman was referred to our center at 16 weeks' gestation. Ultrasound revealed that the bilateral lungs of the fetus were very small due to the compression by massive pericardial effusion. Pregnancy was terminated at 18 weeks, and autopsy of the stillborn baby revealed intrapericardial diaphragmatic hernia and cardiac aneurysm of the right ventricle. In conclusion, when pericardial effusion is observed in a fetus, intrapericardial diaphragmatic hernia, a very rare type of congenital diaphragmatic hernia, must be included in a differential diagnosis.