OBJECTIVE:

To evaluate the sonographic characteristics of fetuses with trisomy 18 and trisomy 13.

METHODS:

From March 2002 to December 2006, we reviewed the database and medical records of 25 cases with trisomy 18 and trisomy 13. The subjects were recruited from pregnant women undergoing prenatal sonographic examinations at 13–28 weeks of gestation and subsequently proven trisomy 18 or 13. The results of ultrasound findings were reviewed in these cases in whom the chromosome analysis confirmed as trisomy 18 and / or 13.

RESULTS:

All cases had at least two abnormal ultrasonographic finding. The common ultrasonographic findings included choroid plexus cysts, abnormal head shape, cardiac anomalies, holoprosencephaly with associated facial anomalies, abnormal feet and/or hands, especially polydactyly, clenched hand and omphalocele. Non-structural abnormal findings such as polyhydroamnios or fetal growth restriction were seen in less than one third of the fetuses.

CONCLUSION:

All fetuses with trisomy 18 or 13 had characteristic ultrasonographic patterns of abnormalities demonstrated at second trimester. Detailed ultrasound at second trimester could effectively screen fetuses with trisomy 18 or 13 for further genetic testing.

Keywords: Genetic ultrasound, trisomy 18, trisomy 13