P032: Screening for chromosomal abnormalities using 2D and 3D ultrasound

Abstract

Recently, first trimester screening programmes have been developed using a combination of ultrasound markers such as nuchal translucency, the presence of nasal bones and maternal serum biochemistry. The aim of this study was to examine the value of first and early second trimester fetal ultrasound using a combination of standard 2D and the more recently developed 3D technology in the detection of fetal aneuploidy together with serial biochemistry. Women opting for first trimester screening were asked to take part independent of their screening result. Each woman attended every 2 weeks for 2D and 3D ultrasound scans between 12 and 20 weeks and had serum taken. Comparisons were then made between biometry and soft markers collected in 2D versus 3D, data between the high-risk and low risk group and biochemical data. 18 women in each group were studied. In 30% of scans 3D imaging was advantageous in detecting or excluding soft markers such as renal pylectasis or echogenic bowel at a mean gestational age 2 weeks earlier than in 2D. Soft markers were detected in 33% of the high-risk group versus 11% in the controls. The rate of change of free bhCG was significantly different between the 2 groups (p = 0.011). This pilot study demonstrates that detailed fetal examination using 2D and 3D ultrasound technology is achievable in the first and early second trimesters. Changes in maternal biochemistry also have a significant role in pregnancy outcome. It is anticipated that with continued further study and development of the 3D technique, clinically useful ultrasound signs of fetal chromosomal abnormalities will be identified in early fetal development.