Cytogenetics of Fetal Anomalies Detected by Ultrasonography

Ultrasound is one of the most important technological advances introduced into modern obstetrics; its use has revolutionized the prenatal detection of foetal structural anomalies The aim of this study was to estimate the risk of chromosomal abnormalities associated with different foetal anomalies detected prenatally at the time of routine ultrasound screening. A prospective study was done on 344 fetuses with one or more structural foetal anomalies detected during routine antenatal second or third trimester scanning by ultrasonography between January 2003 and December 2006. Maternal age ranged between 17 and 43 years (mean 29 ± 6 years) and gestational age ranged between 18 and 25 weeks (mean 20 ± 1 weeks). Foetal anomalies detected in this study included neural tube defects (NTD), renal anomalies, congenital heart disease (CHD), skeletal anomalies, cystic hygroma, anterior abdominal wall defects and intrauterine growth retardation (IUGR). Cytogenetic analysis was done to all 344 samples and revealed normal 46, XX female or 46, XY male karyotyping in 272 samples (79.07 %), and abnormal karyotype in 72 cases (20.93%). Chromosomal abnormalities included trisomies in 34 cases (9.88%), monosomies mainly Turner syndrome in 28 cases (8.13 %), polyploidies and structural chromosomal rearrangements including chromosome 22 microdeletion in 10 cases (2.9%). In conclusion: foetal structural anomalies are usually associated with high risk of chromosomal abnormalities and foetal karyotyping is mandatory to verify the underlying aetiology and offer proper genetic counseling.