[Clinical analysis of 31 cases of fetal umbilical artery thrombosis]

Objective: To analyze the ultrasonic manifestations, clinical features, high risk factors and key points of pregnancy management in prenatal diagnosis of umbilical artery thrombosis (UAT). Methods: The data of 31 pregnant women of UAT diagnosed by prenatal ultrasonography and confirmed after birth from July 2017 to July 2022 at the Women's Hospital, Zhejiang University School of Medicine were retrospectively analyzed, including the maternal characteristics, pregnancy outcomes and fetal complications. In addition, the baseline data and pregnancy outcomes were compared in 21 patients who continued pregnancy after diagnosis of UAT. Of the 21 UAT cases that continued pregnancy, 10 cases were treated with low molecular weight heparin (LMWH; LMWH treatment group), while the other 11 patients had expectant treatment(expectant treatment group). Results: The age of the 31 pregnant women was (30.2±4.7) years, of which 5 cases (16%,5/31) were advanced age pregnant women. The gestational age at diagnosis was (32.9±4.0) weeks, and the gestational age at termination of pregnancy was (35.6±2.9) weeks. In 31 fetuses with UAT, 15 cases (48%) had fetal distress, 11 cases (35%) had fetal growth restriction, and 3 cases (10%) had intrauterine stillbirth. There were 28 cases of live births, including 26 cases by cesarean section and 2 cases by vaginal delivery. There were also 3 stillbirths, all delivered vaginally. Four neonates had mild asphyxia and two newborns had severe asphyxia. Among the 31 cases, 10 cases were terminated immediately after diagnosis, the gestational age at diagnosis was (35.9±2.9) weeks. Another 21 pregnancies continued, and their gestational age at diagnosis was (31.4±3.7) weeks. The median prolonged gestational age in LMWH treatment group was 7.9 weeks (4.6-9.4 weeks), and all were live births. The median prolonged gestational age in the expectant treatment group was 0.6 weeks (0.0-1.0 weeks), and 2 cases were stillbirths. There was a statistically significant difference in prolonged gestational age (P=0.002). Conclusions: Ultrasound is the preferred method for prenatal detection of UAT. Clinicians need to be vigilant for UAT when a newly identified single umbilical artery is detected by ultrasound in the second or third trimesters. The decision to continue or terminate the pregnancy depends on the gestational age and the condition of fetus. Attention should be paid to fetal movements as the pregnancy continues. The treatment of LMWH as soon as possible after diagnosis of UAT may improve the pregnancy outcome.