Absent pulmonary valve syndrome: prenatal cardiac ultrasound diagnosis with autopsy correlation

Absent pulmonary valve syndrome (APVS) is a rare conotruncal anomaly consisting of a severely hypoplastic pulmonary valve with annular stenosis, aneurysmal dilatation of main pulmonary artery with dilatation of one or both pulmonary artery branches, and a ventricular septal defect. Here, we report a prenatal echo diagnosis of APVS in a 27-year-old primi gravida at 20 weeks of gestation confirmed on fetal autopsy. A 'bow tie'-like hypoechoic shadow in fetal cardiac ultrasound observed by us in a modified four-chamber view was suggestive of aneurysmal dilatation of branch pulmonary arteries. The consequences of continuation of pregnancy including immediate neonatal complications and possible medical and multistaged surgical interventions were well explained. Parents opted for medical termination of pregnancy. Autopsy findings of the fetus were consistent with the prenatal echo diagnosis of APVS. The presence of patent ductus arteriosus seen in the autopsy may be the cause of severe heart failure evidenced by the abnormally large congested liver, dilated right heart chambers, and tricuspid valve annulus. We infer that the prenatal diagnosis of APVS may be possible with a high degree of accuracy with characteristic fetal echocradiographic findings such as 'bow tie'-like or 'ballooning'-like shadows observed in this case. The presence of ductus confirms definite fetal loss and the parents can be counselled accordingly. However, when the ductus is absent, decision-making is difficult as the fetus is going to survive.