Second trimester ultrasound examination for risk assessment of chromosomal
abnormalities remains an important component of prenatal evaluation. We have
conducted a retrospective study to evaluate the efficiency of
ultrasonographic screening for the markers of chromosomal aberrations and to
classify ultrasonographic markers according to the aberration they were
found with. Over a 10 year period we performed 620 karyotype analyses of
fetal blood taken by cordocentesis after detection of fetal anomalies in a
second trimester scan in unselected population and 216 samples of peripheral
blood of neonates having phenotypic features suspected for
chromosomopathies. Ultrasound examination and cytogenetic data were obtained
from the laboratory database. Chromosomal abnormalities were found in 36
(5,8%) fetuses with anomalies. Most frequently chromosomal aberrations were
detected in fetuses with multiple anomalies (13,3%), heart anomalies
(11,5%), short femurs (12,5%) and polyhydramnios (7,7%). The success rate of
sonographic examination in detection of Down syndrome was 85%, and in
detection of sex chromosome trisomies 80%. Trisomy 18, trisomy 13 and
polyploidy were found prenatally in 100% each. Nearly 42% of trisomy 21
fetuses had heart anomaly, 35,3% polyhydramnios and 17,7% short femurs.
Trisomy 18 fetuses had polyhydramnios in 87,5%, CNS anomalies in 62,5% and
symmetrical IUGR in 50% of cases. All of the fetuses with monosomy X had
short femurs. Ultrasonographic evaluation is the most sensitive screening
method for the identification of fetuses having a high risk rate for
chromosomal abnormalities in a low risk population.
