[Analysis of 21 723 Pregnant Women's First Trimester Screening for Down Syndrome in Sichuan Province].

OBJECTIVE: To compare the effect of different first-trimester screening programmes for Down syndrome in Sichuan Province. METHODS: We retrospectively collected the data of singleton pregnancies that were screened by serum biochemistry markers combined with nuchal translucency screening tests in the first trimester in Prenatal Diagnosis Center of West China Second University Hospital of Sichuan University from January 2011 to December 2017. The fetal chromosome results were obtained by amniocentesis or by telephone follow-up. The screening effect of maternal age, nuchal translucency thickness, maternal serum biochemistry markers and combined screening in the first trimester were analyzed. RESULTS: Among the 21 723 singleton pregnancies, 33 cases were diagnosed as Down syndrome, and 19 cases were diagnosed as trisomy 18 sex chromosome abnormalities were found in 4 cases, and other chromosome abnormalities were found in 8 cases. For the combined screening, the detection rate of Down syndrome was 72.73%, and the false positive rate was 2.49%; the detection rate of trisomy 18 syndrome was 73.68% with the false positive rate of 0.39%. With a 5% false positive rate, maternal age, nuchal translucency thickness, serum biochemistry markers and combined screening would respectively detect 15.15%, 57.58%, 60.61% and 87.88% of Down syndrome fetuses. CONCLUSION: Compared with the other three screening programmes, the combined screening can effectively screen fetuses with Down syndrome and other chromosomal abnormalities.