The SD value of the umbilical artery refers to the ratio of systolic to diastolic pressure in the umbilical artery of the fetus during pregnancy, which is correctly expressed as the S/D value of the umbilical artery and fluctuates constantly. Usually, the S/D value of the umbilical artery is high in early and middle pregnancy, and the normal value will not exceed 5.5; it can gradually decrease in middle and late pregnancy, and it is usually considered normal to be less than 3 in late pregnancy. The umbilical artery is the key to the placental circulation of the fetus, reflecting the speed of blood flow changes during the cardiac cycle, and can be used to determine the blood supply of the umbilical artery and whether the fetus is able to receive blood supply properly. As gestation continues to progress, a decrease in peripheral vascular resistance and an increase in blood perfusion to the placenta may manifest as a decrease in the S/D value of the umbilical artery. The normal value of umbilical artery S/D in early pregnancy before 24 weeks is usually considered to be around 3.5-5.5 and not more than 5.5; the normal value of umbilical artery S/D in mid pregnancy to around 30 weeks can be controlled at 2.5-5.0 and usually does not exceed this range; the normal value in 36 weeks is mostly 2.5-4 and usually does not exceed 4; the normal value of umbilical artery S/D in late pregnancy is usually considered to be 1.7-3 and less than 3 is considered to be the normal range. Maternal vascular abnormalities, changes in blood viscosity, umbilical cord and placental dysplasia may all result in abnormal umbilical artery S/D values. Maternal umbilical vascular stenosis, hyperthyroidism, increased blood viscosity, umbilical cord entanglement and other abnormalities affecting placental circulation, fetal malformations, intrauterine hypoxia due to placental insufficiency and other factors may all lead to increased umbilical artery S/D values. It is recommended that women during pregnancy go to the hospital for regular checkups to detect fetal development at any time and to provide timely and reasonable treatment in case of abnormalities.
Support Us
Discussion
Share your experience, or seek help from fellow patients.
