[The role of ultrasonography in second trimester screening for fetal chromosome aberrations]

The role of ultrasound examination in second trimester screening for fetal aneuploidies.

Authors sought to determine the frequency of ultrasound findings in major chromosomal defects. They also tried to evaluate possible patterns of ultrasound signs of fetal chromosomal defects.

Through the time period of 15 years (1999-2004) 22,150 fetal karyotypings were done, and 514 abnormal karyotypes (2.3%, 514/22,150) were diagnosed prenatally. Congenital anomalies of these fetuses, detected by second trimester sonography, were analyzed in this study.

Of the 514 chromosome aberrations, 207 fetuses with trisomy 21 (40.3%), 70 fetuses with trisomy 18 (13.6%), 28 fetuses with trisomy 13 (5.4%), 69 fetuses with Turner syndrome (13.4%) and 12 fetuses with triploidy (2.3%) were detected. The incidences of major structural defects and minor anomalies were evaluated then ultrasound signs with the highest incidences were established in each of the major chromosomal defects.

This study may help to select the "optimal components" of the genetic sonogram that would assist the counseling of women for the risk of a chromosomal abnormality. Other advantages of such approach could be the standardization of the contents of ultrasound examination among different health care providers and institutions, and a decrease in false-positive rates.