Abstract： Objective:To explore the prognosis of umbilical cord cysts in fetuses with structural abnormalities diagnosed by prenatal ultrasonography.Methods:This retrospective study involved 109 cases of umbilical cord cysts diagnosed by ultrasound at Beijing Obstetrics and Gynecology Hospital from January 2016 to December 2020. According to the ultrasound findings, these cases were divided into the isolated umbilical cord cyst, umbilical cord cyst with soft ultrasound markers, and umbilical cord cyst with fetal malformation groups. Chi-square was performed for statistical analysis to compare the prognosis. Results:(1) Among 109 cases of umbilical cord cysts, 55 cases (50.5%) were isolated, 20 (18.3%) were complicated by soft ultrasound markers, and 34 (31.2%) cases were complicated by fetal malformation. After excluding two cases of multiple cysts at different locations, the incidence of umbilical cord cysts at the placental end, free segment, and fetal terminal with other ultrasound abnormalities in the remaining 107 cases increased sequentially [27.5% (14/51), 10/17, and 76.9% (30/39), χ2=22.20, P<0.001]. The incidence of umbilical cord cysts with other ultrasound abnormalities at the fetal end was higher than at the placental end ( χ2=21.65, P<0.001). (2) A total of 60 fetal malformations were detected, dominated by fetal ventricular septal defect, omphalocele, giant bladder, fetal edema, and nuchal cystic hygroma, et al., mainly involving the cardiovascular system, urogenital system, anterior abdominal wall, and skeletal system. (3) Eighty-nine cases were followed up to the end of the pregnancy, and 21 (23.6%) of them had adverse outcomes. The prognoses of isolated umbilical cord cyst cases were all good. Two pregnancies (2/18) were terminated in the umbilical cord cyst with ultrasound soft markers group. In the group of umbilical cord cyst with fetal malformation, 19 pregnancies (19/26, 73.1%) had adverse outcomes, including pregnancy termination, intrauterine fetal demise, and perinatal death. Conclusions:The prognosis of isolated umbilical cord cysts is generally good. The umbilical cord cyst complicated by soft ultrasound marker and fetal malformation can have adverse outcomes, while conditions might be worse in those with fetal malformation. When an umbilical cord cyst is revealed, a systematical examination is recommended to identify whether it is combined with other ultrasound abnormalities.