Sonographic findings and fetal chromosomal studies undertaken prenatally by fetal blood sampling using cordocentesis.

Prenatal karyotyping was carried out on 206 pregnancies with sonographic abnormalities, including fetal malformations, growth retardation and disorders of the amniotic fluid volume. Overall, chromosomal aberrations were detected in 37 cases (18.0%), but the frequency of chromosomal aberrations was 8.2% in fetuses with a single anomaly and 52.7% in fetuses with multiple anomalies. The chromosomal risk was very high in malformations associated with growth retardation (81.8%) or with both growth retardation and disorders of the amniotic fluid volume (82.4%). High rates of chromosomal aberrations were observed in cases of heart anomalies, diaphragmatic hernia, urinary tract obstruction, hydrocephalus, intestinal atresia, abdominal wall defect and fetal effusion/hydrops. In fetuses at high risk of chromosomal aberrations, cordocentesis for rapid karyotyping is justified in the second or third trimester.