The umbilical cord is very important to the fetus, and if there is a problem with the umbilical cord, the fetus will be in danger. Therefore, in addition to testing the health of the fetus, the mother-to-be should also pay attention to the problem of anticipation, and if there is an umbilical cord knot, she must go to a regular specialized hospital for medical treatment. What is a knot in the umbilical cord? Umbilical cord knots can be categorized into two types: true knots and false knots. True umbilical cord knot is rare, it is caused by the umbilical cord being too long in early pregnancy (3~4 months), the umbilical cord forms a loop in the uterine cavity, and the fetus moves through the loop, the incidence is 0.5%~3%. The incidence is 0.5%~3%. After the formation of the true knot, if the knot is not tightened, there is no symptom, but if it is tightened, the blood circulation of the fetus is blocked, resulting in fetal underdevelopment or fetal death in the uterus. Color ultrasound Doppler has a high diagnostic accuracy for umbilical cord bypass or hitch, but it is still difficult to accurately diagnose umbilical cord knotting. Three-dimensional ultrasound imaging, i.e. 3D ultrasound, can correctly determine the direction of the umbilical cord in the uterine cavity and its relationship with the fetus, and has a certain degree of accuracy in the diagnosis of umbilical cord knotting. However, the prevalence rate in county hospitals is low, so the prenatal diagnosis rate of umbilical cord knot is low. Hazards of umbilical cord knotting If the umbilical cord is only knotted and not stretched, it is generally not harmful, but once it is stretched, it will affect the transportation of oxygen and nutrients, resulting in poor development of the fetus, or even fetal death in the uterus. Warm tips: normal umbilical cord sound and image performance. The longitudinal section of the umbilical cord in amniotic fluid is in the form of a long rope, shaped like a twist. The two umbilical arteries spiral around the umbilical vein. The umbilical cord envelope and vessel walls are strongly echogenic, and the lumen is anechoic. In the cross section, there are three dark areas arranged in a zigzag pattern, with a large vein and fluctuating arteries. The cross-sectional diameter is about 1-2 cm, and color Doppler can show color maps and arterial and venous spectra.