Influence of Gestational Age Estimated with Biparietal Diameter on Second Trimester Down Syndrome Screening / 中国医科大学学报

ABSTRACT

Objective to evaluate the impacts of 6 standard comparible tables of biparietal diameter(BPD)-gestational age to the second trimester Down syndrome screening and the individual risk rate for pregnant woman. Methods A total of 25 346 pregnant woman with gestational age be-tween 12 to 20 weeks were recruited and analyzed in the study,including 32 Down syndrome. For each pregnant woman,we calculated the gestation-al age by six different BPD-gestational age tables,and the prenatal screening risk value of gestational age. then ROC curve,detection rate and posi-tive rate were used to evaluate the effect of different control tables on the screening results. In addition,individual risk rate was used to determine the influence of gestational age deviation on pregnant woman. Results According to the ROC,we found that our self-designed BPD table had the best AUC(0.972),while the table designed by a hospital in Shanghai had the least AUC(0.923). the difference was significant by statistic test(P =0.045). With the same detection rate of 75%,we found our self-designed table had the least positive rate with only 2.3%,and the cutoff was 1∶280, while the table of Chinese Obstetrics and Gynecology had the highest ratio(4.8%),and the cutoff was 1∶345. Our results suggest that once gesta-tional age is estimated to be higher than actual age,the risk will be higher and the positive rate will increase. However,if gestational age is estimated to be smaller,the risk will be smaller and the negative rate will increase. Conclusion the impacts of different tables on Down syndrome screening are different. Our self-designed BPD table is the most effective to estimate gestational age,and the control table of Hongkong is ranked No.2. the wrong estimation of gestational age will largely affect the individual risk of pregnant woman.