目的: 分析产前超声诊断单脐动脉(single umbilical artery， SUA)发生率及合并胎儿结构畸形类型。方法: 回顾性分析2013年1月1日至2022年1月31日连续在苏州大学附属儿童医院行产前超声检查的单胎妊娠胎儿141 577例，以产后检查脐带数目或病理检查为标准，统计单胎SUA的发生率及其合并畸形的情况。结果: 单胎SUA发生率为0.55%（778/141 577），其中单纯性SUA（isolated SUA，iSUA）占60.93%（474/778），非单纯性SUA（non-isolated single umbilical atery，niSUA）为39.07%（304/778）。SUA中，左、右侧脐动脉缺失率分别为51.7%（402/778）、48.3%（376/778）。右侧脐动脉缺失合并畸形百分比高于左侧[44.95%（169/376）比33.58%（135/402）P=0.023 1]。niSUA中，即SUA合并胎儿畸形中，共477例次畸形，其中心血管畸形最常见，占36.27%（173/477），其次为泌尿生殖系统[19.50%（93/477）]、中枢神经系统[11.95%（57/477)]。487例进行了染色体检查，异常率为8.83%（43/487）niSUA胎儿的染色体异常发生率（13.79%,28/203）明显高于iSUA（5.28%,15/284）胎儿（P=0.001 1)。随着SUA合并畸形种数的增加，染色体异常的发生率也不断上升，合并4种及以上畸形胎儿的染色体异常发生率高达37.5%（3/8）。染色体核型异常中以18-三体综合征最常见，占30.23%（13/43）。结论: 单胎SUA发生率为0.55%，SUA合并胎儿畸形占39.07%，其中心血管畸形最常见，占所有畸形例次的36.27%。当超声显示同时存在4种及以上畸形时，其中近40%伴有染色体核型异常。

Objective: To analyze the incidence of single umbilical artery (SUA) diagnosed by prenatal ultrasound and the types of combined fetal structural malformations. Methods: A retrospective analysis was performed on 141 577 singleton pregnancies who underwent continuous prenatal ultrasonography in Children’s Hospital of Soochow University from January 1, 2013 to January 31, 2022. Based on postpartum umbilical cord data or pathological examination，the incidence of SUA in singleton pregnancies was calculated and the combined malformations were analyzed. Results: The incidence of SUA was 0.55% (778/141 577) in singleton pregnancy, with isolated single umbilical artery (iSUA) accounting for 60.93% (474/778) and non-isolated single umbilical artery (niSUA) accounting for 39.07% (304/778). The absence rate of the left and right umbilical arteries was 51.7% (402/778) and 48.3% (376/778), respectively. The SUA with absence of right umbilical artery had a higher incidence of malformation comorbidities than those with absence of left umbilical artery [44.95% (169/376) vs. 33.58% (135/402)] (P=0.023 1). The frequency of malformations was 477 in 304 SUA fetuses, and cardiovascular malformation was the most commonly seen, accounting for 36.27% (173/477). Chromosomal examination was performed in 487 fetuses,with a chromosomal abnormalities rate of 8.83%(43/487). Incidence of chromosomal abnormalities in niSUA fetuses (13.79%,28/203) was significantly higher than that in iSUA fetuses (5.28%,15/284) (P=0.001 1). The incidence of chromosomal abnormalities rose along with the increase in the number of malformations in fetuses with four or more malformations, reaching 37.5% (3/8). Trisomy 18 syndrome was the most common abnormal chromosome karyotype (30.23%, 13/43). Conclusions: The incidence of SUA in singleton pregnancies is 0.55%, and iSUA accounts for 39.07%. Among SUA combined fetal malformations, cardiovascular malformations are the most common, with a proportion of 37.5%. When ultrasound indicates the presence of four or more malformations in fetuses, 40% of them may accompany with chromosome karyotype abnormalities.