Prenatal Evaluation of Genetic Abnormalities in Fetuses With Single Umbilical Artery: A Retrospective Cohort Study.

OBJECTIVE: To investigate the genetic factors associated with fetal single umbilical artery (SUA) and concomitant structural anomalies. METHODS: A retrospective review was performed on the ultrasound characteristics of 375 SUA fetuses diagnosed by color Doppler ultrasound at Fujian Provincial Maternity and Children's Hospital from February 2010 to February 2022. Single-nucleotide polymorphism (SNP) array and karyotype analysis were performed to evaluate the relationship between chromosomal abnormalities and isolated/nonisolated SUA. RESULTS: Most pregnant women were aged 25-35 years, and 210 were primigravida or nulliparous women with a history of miscarriage. Among 375 fetuses, 101 had isolated SUA (iSUA), 116 had SUA with additional abnormal ultrasound soft markers, and 158 had SUA with congenital structural malformations (predominantly cardiovascular and genitourinary). The chromosomal karyotype abnormality rate was 16.53%, significantly higher in the SUA with multiple system malformation group. SNP-array testing in 152 cases identified 11 cases of chromosome number abnormalities and 13 microdeletions or microduplications. Of the 131 cases with successful follow-up, 77 term live births, 49 elective terminations, 2 preterm births, and 3 deaths. All 29 cases in the SUA with multiple system malformation group were terminated. CONCLUSIONS: SUA was most common in pregnant women aged 25-35 and significantly higher in primigravidas and nulliparous women with a history of miscarriage. Female fetuses had a higher SUA incidence than males. Chromosomal abnormality rates increased with associated malformation number and occurred even in iSUA. SNP-array offers a higher resolution in detecting chromosomal microdeletions or microduplication syndromes compared to conventional karyotyping.