Umbilical cord coiling index in predicting neonatal outcomes: a single-center cross-sectional study from Vietnam

Abnormal umbilical coiling (AUC) is one of the common occurrences of umbilical cord abnormalities leading to poor neonatal outcomes.

This study aims to investigate the association between antenatal umbilical coiling index (aUCI) and perinatal outcomes as well as the risk factors relating to AUC.

A cross-sectional study was conducted between June 2022 and June 2024 at Hue University of Medicine and Pharmacy, Vietnam. The study enrolled 337 full-term primigravida with uncomplicated singleton pregnancies who underwent transabdominal ultrasound between 37⁺⁰ and 41⁺⁰weeks of gestation for aUCI by color Doppler ultrasound. The aUCI was calculated as the reciprocal of the distance between a pair of coils. The aUCI was classified as hypo-, hyper-, and normocoiled. The patients were monitored until birth delivery, and any adverse antenatal complications were noted.

The mean aUCI among hypo-, normo-, hypercoiling group were 0.16 ± 0.003, 0.30 ± 0.06, 0.46 ± 0.04. There was a statistically significant different between the resistance index (RI), pulsatility index (PI) of umbilical artery, PI of middle cerebral artery, and the cerebroplacental ratio (CPR) among 3 groups. Overall, the rate of abnormal fetal heart rate tracing, meconium-stained amniotic fluid, cesarean section rate, fetal growth restriction (FGR), and Apgar scores at 5 mins below 7 points was higher in the hypercoiling group (28.2%, 36.6%, 50.7%, 8.5%, 4.2%, respectively) and hypocoiling groups (5.0%, 10.0%, 35.0%, 17.5%, 12.5%, respectively) compared to the normocoiling group (15.0%, 12.4%, 27.9%, 1.8%, 0.9%, respectively), p < 0.05. In general, AUC increased significantly the risk of FGR and Apgar score at 5 mins < 7 points with odds ratio (OR): 7.63 (95% confidence interval (CI): 2.34-23.15) and OR: 8.70 (95%CI: 1.82-41.69). More than 2-fold increased rate of meconium-stained amniotic fluid, cesarean delivery, and birth weight below 2500 grams were also observed. After adjusting for gestational age, gestational hypertension disorders, gestational diabetes mellitus, oligohydramnios/hydramnios were significantly related to the development of AUC with OR: 4.99; 7.92, 4.96; 4.56, respectively.

Both abnormal umbilical coiling in the form of either hypocoiling or hypercoiling are associated with adverse pregnancy outcomes. Thus, the antenatal umbilical coiling index ought to be detected during routine antenatal care.