Prenatal diagnosis of the umbilical cord torsion at the placental cord insertion site: A case report and literature review

A 35‐year‐old woman (gravida 1, para 0) was admitted to our hospital at 28 weeks' gestation with vaginal bleeding from placenta previa. Severe fetal bradycardia was observed during fetal heart rate monitoring. Ultrasonography showed widely dilated veins on the fetal surface of the placenta and an extraordinarily low umbilical artery peak systolic velocity in the Doppler study. Umbilical cord torsion was suspected. On the subsequent day, we performed a cesarean section due to worsening fetal heart rate patterns. Umbilical artery blood gas analysis indicated severe acidemia (pH 7.063), and umbilical cord torsion was confirmed at the placental cord insertion site. Diagnosing UCT prenatally is challenging; however, it can be suspected by scanning for the widely dilated veins on the fetal placental surface, termed as the “Sunset Sign,” an abnormally low umbilical artery peak systolic velocity, and other fetal Doppler abnormalities.