Trisomies and other chromosome abnormalities detected after positive sonographic findings

Abstract

Objective: To evaluate the rate of trisomies and other chromosome abnormalities after positive ultrasound findings in thefirst and second trimester of pregnancy.

Study design: The study investigated chromosome abnormalities detected in cases with prior abnormal ultrasoundfindings. During a 10-year period there were 1907 invasive interventions carried out with the purpose of chromosome analysis. The intervention was genetic amniocentesis in 1619 cases and chorionic villus sampling in 288.

Results: Karyotyping revealed 103 cases (5.4%) of chromosome abnormalities. Abnormalities with subcutaneous edema were examined: abnormal karyotype was found in 20% of cases with nonimmune hydrops, 48.1% of cases with cystic hygroma and 53.8% of cases with nonimmune hydrops and cystic hygroma together, 8.3% of cases with nuchal edema in the first trimester and 5.5% in the second trimester. The incidence of chromosome abnormalities in cases of cerebral anomalies was 6.3% of cases with ventricular dilatation, 3.6% of cases with choroid plexus cysts and 15.9% of cases with other cranial anomalies. Regarding abnormalities of the heart, isolated echogenic intracardiac focus and ventricular septal defects were not associated with chromosome abnormality, but, in conjunction with other positive ultrasound findings, the incidence of chromosome abnormalities was 7.9% and 26.7%, respectively. Other anomalies of the heart and large blood vessels showed an abnormal karyotype incidence of 18.2%. In cases of unilateral pyelectasis unassociated with other anomalies, the incidence of chromosome abnormalities was 1%. In cases of bilateral pyelectasis or pyelectasis associated with other anomalies, the incidence was 3%. In terms of anomalies of the abdominal wall and abdomen, the incidence of association with chromosome abnormalities was 9.5% in cases of omphalocele, 11.8% in cases of duodenal atresia and 5.7% in cases of echogenic bowel. In cases of short femur and humerus the rate of abnormal karyotypes was 16%.

Conclusion: Ultrasound plays an important role in prenatal diagnosis. In cases of positive ultrasound findings, karyotyping is reasonable.