Prenatal Sonographic Features of Trisomy 18

Abstract

Objective To evaluate the sonographic characteristics of the fetuses with trisomy 18.

Subjects The fetuses proven to be trisomy 18 were sonographically evaluated.

Results Twenty proven cases of trisomy 18 were evaluated by prenatal ultrasound. The indications for sonographic examinations included amniocentesis or cordocentesis due to genetic risk, large-or small-for-date and screening anomalies. Fifteen of twenty had two or more abnormal findings. There were only two cases that no abnormality could be seen. The common sonographic findings included abnormal head shape, abnormalities of extremities, choroid plexus cyst, enlarge cisterna magna, cardiac abnormalities, omphalocele, intrauterine growth retardation and polyhydramnios.

Conclusion Nearly all fetuses with trisomy 18 had abnormal sonographic findings in second or third trimester. Most of them had two or more abnormalities. Although prenatal ultrasound can not permit us to make a definite diagnosis of trisomy 18, it has characteristic pattern of multiple malformations in most cases and warrants cytogenetic testing.