Advancing further the sonographic estimation of Down syndrome risk--how early can we go?

Screening for congenital heart disease during anatomical survey ultrasonography

Congenital heart disease (CHD) is among the most common congenital abnormalities. The prevalence of CHD ranges between 0.6% and 1.2% of live births. Despite its high prevalence, CHD is also among the most commonly missed abnormalities during prenatal ultrasound examination. A simple yet systematic approach to fetal heart examination, regular feedback, and implementation of training programs could improve detection rates and, in turn, neonatal outcome.

Role of first-trimester sonography in the diagnosis of aneuploidy and structural fetal anomalies

OBJECTIVE

We sought to determine the sensitivity of the first-trimester scan in the early diagnosis of aneuploidy and structural fetal anomalies in an unselected low-risk population.

METHODS

This was a retrospective chart review of all patients having first-trimester scans between 2002 and 2009. At our center, a survey of fetal anatomy is performed at the time of nuchal translucency assessment at 11 weeks to 13 weeks 6 days. A second-trimester scan is done at 20 to 23 weeks and a third-trimester scan at 32 to 35 weeks. Isolated sonographic findings of choroid plexus cysts and echogenic intracardiac foci were excluded. Lethal anomalies and those requiring immediate surgical intervention at birth were considered major structural anomalies. All scans were performed by a single sonologist certified by the Fetal Medicine Foundation. All neonates were examined at birth by a pediatrician.

RESULTS

Our study included 1370 fetuses. Six cases of aneuploidy (0.4%) were detected. The first-trimester scan detected 5 of 6 cases of aneuploidy (83%), confirmed by karyotype. There were 36 cases of structural fetal anomalies (2.6%); 20 (1.5%) were major anomalies. The first-trimester scan detected 16 of 36 (44%); 20 (56%) were identified by second- or third-trimester scans. The first-trimester scan detection rate for major structural anomalies was 14 of 20 (70%). The 5 that were missed by the first-trimester scan were detected by a second-trimester scan.

CONCLUSIONS

Our study emphasizes the importance of the first-trimester scan in the early detection of aneuploidy and structural fetal anomalies. In this small unselected low-risk population, the first-trimester scan detected 83% of aneuploidies and 70% of major structural anomalies. Our results are comparable to previously published studies from other centers and further exemplify the invaluable role of the first-trimester scan in the early detection of aneuploidy and structural anomalies in an unselected low-risk population.