Abstract: Objective：To investigate the role of chromosome karyotype analysis and single nucleotide polymorphism array (SNP-array) in prenatal diagnosis of abnormal fetuses. Methods：From January 1, 2017 to December 31, 2018, 278 cases of pregnant women with fetal ultrasound abnormalities who received amniotic fluid puncture at our hospital were collected, and chromosome karyotype analysis and SNP-array were performed simultaneously. Results：The karyotype of amniotic fluid was analyzed in 278 cases, and the culture success rate was 99.28% in 276 cases. The positive detection rate of chromosome karyotype analysis was 8.33% (23/276). The positive detection rate of SNP-array was 17.03% (47/276). The difference of positive detection rate between the two test methods was statistically significant ( χ2=9.424, P=0.002). In the cases with normal karyotype, the positive detection rate of SNP-array was 11.46% (29/253), among which the detection rate of pathogenic copy number variations (CNVs) was 2.76% (7/253), variants of unknown significance (VOUS) was 8.70% (22/253). The positive CNVs detection rate in abnormal fetus with NT thickening, bones, muscles and cardiovascular system is highest, followed by fetus with urinary tract malformation and abnormal single soft ultrasound index. No pathogenic CNVs were detected in fetal facial abnormalities, digestive system abnormalities, respiratory system abnormalities, etc. Conclusions：SNP-array technique has certain advantages in the detection rate of abnormal results, while chromosome karyotype analysis can make up for the deficiency of SNP-array in chromosome balance translocation and inversion. Chromosome karyotype analysis combined with SNP-array technique has good application value and space in ultrasonic abnormal fetus.

Key words: Polymorphism, single nucleotide；, Prenatal diagnosis；, Amniocentesis；, Ultrasonography, prenatal；, Chromosome karyotype analysis；, Single nucleotide polymorphism array