Ultrasonographic diagnosis of secondary cardiac position alterations led by fetal thoraco-abdominal anomalies: a report of three cases.

Background: Congenital diaphragmatic hernia (CDH) and congenital diaphragmatic eventration (CDE) are rare congenital anomalies. They occur in approximately one in 2,000-3,000 and 2,500-5,000 children respectively. It is difficult to distinguish between CDE and right diaphragmatic hernia in fetal period, which can cause changes in the position of the heart and lead to dysplasia of the right lung; absence of the right lung can lead to secondary dextrocardia. These are common in dextrocardia and lung agenesis, which are the main obstacles for diagnosis. Case Description: This paper reports on three cases of fetal extracardiac structural abnormalities leading to secondary cardiac position changes. Two cases were identified with excessive left displacement of the fetal heart due to congenital right diaphragmatic hernia (right lobe of liver) and congenital right diaphragmatic eventration, respectively. The third case was diagnosed by prenatal echocardiography as having primary dextrocardia with an abnormal origin of the right pulmonary artery. Comparative analysis of pathological results after induced labor showed that two cases were in accordance with prenatal ultrasound diagnosis, and the third case showed that the absence of right lung resulted in secondary dextrocardia and persistent left superior vena cava. Conclusions: CDH and severe diaphragmatic eventration involve three systems: respiration, circulation and digestion. When ultrasound finds that the fetal heart is abnormal, further check is needed to see whether there are lesions in the heart, lung, diaphragm and abdomen; secondary dextrocardia is more common in the absence or dysplasia of the right lung.