Umbilical cord torsion may be visible on ultrasound, but it is not absolute. Ultrasound can provide diagnostic clues, but it cannot be used as a basis for a definitive diagnosis. Generally, you can determine whether the umbilical cord is twisted or not by the blood flow signal and blood flow resistance. The umbilical cord is spiral in shape, the whole umbilical cord is usually not visible on ultrasound, and part of it may be covered up by the fetus. Ultrasound can provide diagnostic clues when the umbilical cord is twisted, but cannot be used as the basis for confirming the diagnosis. To determine whether the umbilical cord is twisted, ultrasound can monitor the umbilical cord’s blood flow signal and blood flow resistance. The blood flow signal is the ratio between the maximum systolic blood flow velocity and the end-diastolic blood flow velocity of the umbilical cord; the peak systolic blood flow reflects the blood flow rate and the end-diastolic blood flow rate reflects the vascular resistance of the placenta, and the greater the vascular resistance, the greater the likelihood of umbilical cord torsion. When the umbilical cord is twisted, there may be abnormal fetal movement. If abnormal fetal movement occurs, it is necessary to go to the hospital in time to clarify the cause, and if there are symptoms of acute hypoxia, it is necessary to terminate the pregnancy as soon as possible.