Screening for trisomy 21 by maternal age, fetal nuchal translucency and maternal serum biochemistry at 11-14 weeks: a German multicenter study

OBJECTIVE

To examine the effectiveness of screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness and maternal serum biochemistry using free beta-human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11-14 weeks of gestation.

METHODS

This was a multicenter study of screening for trisomy 21 by a combination of maternal age, fetal NT and maternal serum free beta-hCG and PAPP-A at 11-14 weeks of gestation, using the methodology developed by the Fetal Medicine Foundation. The distribution of estimated risks for trisomy 21 was determined and the sensitivity and false-positive rate for a risk cut-off of 1 in 300 were calculated.

RESULTS

In total, 3864 singleton pregnancies with live fetuses at 11-14 weeks were examined and the fetal NT and maternal serum free beta-hCG and PAPP-A were successfully measured in all cases. The median maternal age was 33 (range 15-46) years and, in 1271 (35.8%), the age was 35 years or more, the median gestation at screening was 12 (11-14) weeks and the median fetal crown-rump length was 64 (range 45-84) mm. The fetal NT was above the 95th centile in 73.7% (14 of 19) of trisomy 21 and in 4.8% (169 of 3505) of normal pregnancies. The estimated risk for trisomy 21 based on maternal age, fetal NT and maternal serum free beta-hCG and PAPP-A was 1 in 300 or greater in 6.6% (233 of 3505) of normal pregnancies, in 84.2% (16 of 19) of those with trisomy 21 and 88.9% (24 of 27) of those with other chromosomal defects.

CONCLUSIONS

In Germany, the results of screening for chromosomal defects by measurement of fetal NT and maternal serum biochemistry, in centers with appropriately qualified sonographers, are similar to those reported in the UK using the same methodology.

Screening for trisomy 21 by fetal nuchal translucency and maternal age: a multicenter project in Germany, Austria and Switzerland

OBJECTIVE

To examine the effectiveness of screening for trisomy 21 by a combination of maternal age and fetal nuchal translucency thickness at 10-14 weeks of gestation in Germany, Austria and Switzerland.

METHODS

This was a multicenter study of screening for trisomy 21 by a combination of maternal age and fetal nuchal translucency thickness at 10-14 weeks of gestation. All the sonographers involved in the study had received The Fetal Medicine Foundation Certificate of Competence in the 10-14-week scan. Fetal nuchal translucency thickness and crown-rump length were measured in 23 805 singleton pregnancies with live fetuses. In each case the risk for trisomy 21 was estimated on the basis of maternal age and fetal nuchal translucency thickness for crown-rump length with the use of The Fetal Medicine Foundation's software. The distribution of estimated risk was determined and the sensitivity and false-positive rate for a risk cut-off of 1 in 300 was calculated.

RESULTS

Fetal nuchal translucency thickness was successfully measured in all 23 805 pregnancies and outcome was available in 21 959. The median maternal age was 33 (range 15-49) years and in 7935 (36.1%) the age was 35 years or greater. The median gestation at screening was 12 (10-14) weeks and the median fetal crown-rump length was 61 (range 38-84) mm. The estimated risk for trisomy 21 based on maternal age and fetal nuchal translucency thickness for crown-rump length was 1 in 300 or greater in 13.0% (2800 of 21 475) normal pregnancies, in 87.6% (184 of 210) of those with trisomy 21 and in 87.2% (239 of 274) with other chromosomal defects.

CONCLUSIONS

In Germany, Austria and Switzerland the results of screening for chromosomal defects by measurement of fetal nuchal translucency thickness, in centers with appropriately qualified sonographers and using The Fetal Medicine Foundation's software, are similar to those reported in the UK using the same methodology.