Complete atrioventricular septal defect (CAVSD) is a fetal cardiac malformation (5% of all cardiac malformations) that can be detected prenatally with a reserved prognosis. The diagnosis can be suspected early at the end of the first trimester using the transabdominal or transvaginal ultrasound approach. Generally, the diagnostic can be established during the mid-trimester scan at 19-24 weeks of gestation. The percentage of antenatal diagnostic of CAVSD is between 57-92%. This review aims to analyze the anatomical principles and the ultrasound techniques that can improve the prenatal diagnosis of CAVSD. We have also analyzed the structural and genetic anomalies frequently associated with CAVSD.