RESUMEN
BACKGROUND: Continuous technological improvement made in the field of ultrasound applied to obstetric diagnostics (see tridimensional sonography) has contributed to a better and non-invasive early diagnosis of fetal malformations. METHODS: To evaluate the usefulness of ultrasound in detecting early chromosomal derangements, the authors carried out a high resolution transvaginal sonography (> 6.5 mHz), between the 10th and 14th week of gestational age, on 650 pregnant women at risk for congenital anomalies and afterwards they were subjected to early amniocentesis RESULTS: Sonographic fetal anomalies were seen in 61 cases (9.3%). The incidence of fetal anomalies in these cases was 52.5%. Trisomies and number of sexual chromosome anomalies were seen, especially, in the cases of cystic septated hygroma and fetal nuchal translucency > or = 3 mm which are the most frequent sonographic markers of chromosomopathies. CONCLUSIONS: Although further studies are necessary, these findings suggest the usefulness of high resolution transvaginal sonography for the early screening of chromosomopathies.