New ultrasound markers

Effective first-trimester screening for trisomy 21 is provided by a combination of maternal age, fetal NT thickness, fetal heart rate and maternal serum free ß–hCG and PAPP-A. Chorionic villous sampling is carried out in 3% of pregnancies and 90% of fetuses with trisomy 21 are detected

• Assessment of the new markers improves the performance of combined screening by increasing the detection rate from 90% to 95% and reducing the invasive testing rate from 3% to 2.5%
• Examination of the new markers requires appropriate training of sonographers and certification of their competence in carrying out these scans
• During the ultrasound scan the fetal position may be such that it could be impossible to examine all four of the new markers