Background: Fetal echocardiography has achieved high sensibility and specificity rates and it has become a reliable tool to detect intra-uterine congenital heart defects.
Objectives: The purpose of the present study was to clarify the potential of anatomo-clinical correlation in fetal echocardiography not only for diagnosing heart defects, but also for understanding and following their morphogenesis and natural history in utero.
Methods: Nine hundred pregnancies, referred by several first-level centers, have been followed up from the sixteenth week to birth, and the newborn baby has been studied, too. In case of either voluntary abortion, or intra-uterine or neonatal death, a post-mortem examination was performed whenever possible.
Results: Since 1982, 110 fetal heart defects have been detected: 94 were diagnosed by means of fetal echocardiography (in 21/94 an autopsy was carried out) and 16 were directly observed at the post-mortem (spontaneous or voluntary abortions not previously referred). The heart defects most commonly observed were the atrioventricular (14.5%), ventricular (9.0%), and atrial (7.2%) septal defects, the absent left atrioventricular connection (8.1%), and atrial isomerism (6.3%). The congenital heart defects diagnosed in utero vary from those observed in the newborn and infants in terms of distribution (because of difficulties in diagnosis, selection of pregnancies, and differences in manifestation) and morphology (because of the coexistence with other extracardiac malformations, the changes due to altered fetal hemodynamics, and the intrauterine evolution of the morphology of cardiac defects).
Conclusions: Heart defects observed in utero have a peculiar prevalence and a different morphology in respect to their infantile counterparts and can be followed in their morphologic evolution.