For a pregnant woman, it is particularly important to do prenatal check ups on time, which can timely grasp the development of the fetus and the physical condition of the pregnant woman herself. Among them, ultrasound examination is one of the essential examination items. So, what is S/D at 22 weeks of pregnancy?
S/D is the ratio of systolic to diastolic velocities. S represents peak systolic velocity, reflecting blood flow, and D represents end diastolic velocity, reflecting placental vascular resistance. The S/D value of umbilical artery blood flow in normal pregnancy gradually decreases with the increase of gestational age. S/D ranges from greater than 4 in early pregnancy to less than 3 or even below 2 as gestational age increases.
At 22 weeks of pregnancy, the S/D value is generally less than 4 or 3. The gradual decrease in S/D value indicates that the placenta is gradually maturing, and the blood vessels in the placenta, including the arteries and veins circulating in the uterus during pregnancy, are gradually increasing and thickening, while the peripheral resistance of the placenta decreases. Ensure that the umbilical artery maintains sufficient blood flow during diastole to meet the needs of the fetus.
The value displayed by S/D examination, which is the umbilical blood flow value, is an important reference value that can reflect whether the baby has hypoxia, and the normal value of this value varies at different stages. If the S/D value of the fetus is found to be low during pregnancy examination, it is necessary to promptly report this situation to your doctor and receive treatment in a timely manner.
