Abstract: This study investigated the clinical value of prenatal ultrasound combined with non-invasive prenatal testing (NIPT) in the screening of fetuses with chromosomal abnormalities in the second trimester. The imaging data and NIPT results of 6000 pregnant women performed prenatal ultrasound screening were retrospectively analyzed. Among the 6000 cases, 112 cases of abnormal soft index were totally detected, and 93 cases of abnormal structural index were detected by ultrasound. 47 cases of high-risk pregnant women were detected by NIPT, among them 33 cases of trisomy 21 syndrome and 14 cases of trisomy 18. Through the combined diagnosis of ultrasound soft index, ultrasound structural index, NIPT for fetal chromosomal abnormalities, the sensitivity, specificity, positive predictive value and negative predictive value were 86.44%, 99.95%, 94.44% and 99.87%, respectively. For women in the second trimester, prenatal ultrasound or NIPT screening for fetal chromosomal abnormalities has low sensitivity but both high specificity. So the combination of the two methods could effectively improve the sensitivity of screening, which may be useful for early detection important value, thereby improving the reproductive quality.

Key words: second trimester, prenatal ultrasound, non-invasive prenatal testing, chromosomal abnormalities, screening