Prenatal Diagnosis on Ultrasound, Management and Prognosis of Umbilical Artery Thrombosis: A Retrospective Study of 11 Cases

Background Umbilical artery thrombosis (UAT) is a rare occurrence during pregnancy and is responsible for most of the fetal demises. It is usually difficult to diagnose and easy to be missed or misdiagnosed. The purpose of this study is to investigate the prenatal ultrasonographic and clinical features of UAT.Methods The UAT cases from January 2015 to June 2021 in Guangdong Provincial People’s Hospital were collected, and their ultrasonographic and clinical data were analyzed retrospectively.Results 11 cases were diagnosed as UAT by intrapartum and postpartum findings. 8 cases (Case 1-8) were diagnosed as UAT by prenatal ultrasound, in which one umbilical vein (UV) and two umbilical arteries (UAs) were detected in the cross and longitudinal sections of the umbilical cord (UC) and thrombi were found in one UA with the obstructed blood flow in the third trimester; however, two UAs with normal blood flow on both sides of fetal bladder were detected during the second trimester. UC punctures were performed before thrombi appeared in 2 cases (Case 7-8). 3 cases (Case 9-11) were misdiagnosed as single umbilical artery (SUA) until delivery. When UAT was diagnosed, the systolic to diastolic ratio (S/D) values of UA were < the 25th percentile and the pulsatility index (PI) values of UA were < the 5th percentile in all cases. Doppler measurements of middle cerebral artery (MCA) were measured in 3 cases. Among them, PI values of MCA of 2 cases were < the 5th percentile, and the cerebroplacental ratios of all 3 cases were > the 25th percentile. 8 pregnancies were terminated by cesarean section. 2 women gave birth spontaneously. 1 woman underwent vaginal forceps delivery. 8 neonates were transferred to neonatal intensive care unit. All the newborns had good prognosis.Conclusions When the ultrasound shows only one UA in the level of fetal bladder for the first time in the third trimester, both sonologists and obstetricians should be highly alert to UAT. Thorough confirm of the previous examination results is necessary to exclude SUA. Intensive fetal monitoring and emergency cesarean section are necessary to avoid adverse perinatal outcomes.