Normal value of uterine artery

When a woman is pregnant, her uterus will be open and the blood in the arteries will be relatively sufficient, but the normal value is determined by the physical condition of each pregnant woman. As long as the blood flow rate in the uterine artery is normal and the nutrient absorption is normal in the early stages of pregnancy, it will be fine. If the uterine artery blood level increases during pregnancy, it may affect the development of the fetus and the stability of the placenta, so pregnant women should avoid the symptoms of hypertension during pregnancy.

Normal value of uterine artery during pregnancy

There is no definite value for the normal value of the uterine artery during pregnancy. This can be determined based on the pregnant woman's own long-term blood pressure and blood flow conditions to determine whether the uterine artery has a phenomenon of excessive flow rate.

Also, during pregnancy, if the fluctuation range of the uterine artery is monitored, it is mainly for pregnant women with high blood pressure during pregnancy. Hypertension during pregnancy is also a very dangerous physiological disease, so we must actively treat it.

If you have high blood pressure during pregnancy, it will cause growth retardation in the baby in the womb. Secondly, high blood pressure during pregnancy can also easily cause premature placenta formation. Severe high blood pressure can also cause syndrome. Therefore, we must actively control blood pressure during pregnancy.

Uterine artery testing: a small test with a big impact

Ensuring the best environment for fetal growth and development in the uterus mainly depends on the blood circulation between the fetus and the placenta, the blood circulation between the uterus and the villi, and the exchange of substances in the placenta. As the fertilized egg implants, a series of adaptive changes occur in the pregnant mother. Research data show that certain pregnancy complications are often accompanied by changes in the hemodynamics of the uterine artery or umbilical artery.

The Doppler spectral characteristics of the uterine arteries are often used to assess the fetoplacental circulation. Commonly used indicators include the ratio of the maximum systolic blood flow velocity to the end-diastolic blood flow velocity (S/D) of the bilateral uterine arteries in early, middle and late pregnancy and the umbilical artery in mid and late pregnancy, the pulse index (PI) and the resistance index (RI). These are non-invasive auxiliary examination indicators commonly used in clinical practice to assess organ blood perfusion and determine organ function status [1].

The blood circulation of the main uterine artery and its intrauterine branches is very important for embryo implantation and fetal growth and development. Color Doppler ultrasonography in early pregnancy can observe an increase in color blood flow signals in the uterine myometrium; as pregnancy progresses, the uterine artery gradually straightens from being tortuous, and spectral Doppler shows that the high-resistance blood flow in the uterine artery gradually evolves into low-resistance blood flow with rich diastolic components, indicating an increase in uterine blood perfusion. In normal pregnancy, the perfusion volume of the bilateral uterine arteries is not much different, suggesting that the position of the placenta attached to the uterine wall and the degree of uterine right rotation generally do not affect the uterine artery blood flow. Under normal circumstances, according to the hemodynamic principles of fetal-placental circulation, before 26 weeks of pregnancy, the placental circulation resistance decreases due to the increase in the villous vascular bed, and the S/D value decreases accordingly. The decline is fastest in the second trimester. After 26 weeks of pregnancy, due to villous interstitial fibrosis, the S/D ratio decreases slowly and tends to be constant (PI<0.7, RI<0.5, S/D<2.6). As pregnancy progresses, the uterine placental circulation resistance continues to decrease and the perfusion volume gradually increases, which is beneficial to the growth and development of the fetus. Studies have found that in normal pregnancy, the S/D, PI and RI of the uterine artery show a downward trend as the pregnancy progresses. However, when there are pregnancy complications, such as gestational hypertension, intrauterine growth restriction and oligohydramnios, S/D, PI or RI may not necessarily show a downward trend, and may even increase. In addition, in patients with gestational hypertension, S/D, PI and RI are significantly higher than those in normal pregnancy. However, in patients with intrauterine growth restriction and oligohydramnios, these three indicators do not show significant differences compared with normal pregnancy. As an indicator of arterial vascular resistance, PI can indirectly reflect the blood perfusion of local tissues. During normal pregnancy, the hemodynamics of some organs change due to decreased peripheral resistance, increased cardiac output, and increased circulating blood volume[2].

In recent years, many experts have pointed out that in the second trimester of pregnancy, uterine artery RI>0.58 can predict adverse pregnancy outcomes, especially for predicting preeclampsia, fetal growth retardation, and placental abruption with high sensitivity and specificity. When RI<0.58, the risk of adverse pregnancy outcomes is lower. When the uterine artery sd="">3.55, PI>1.458 and RI>0.728 in mid-pregnancy, it can effectively predict gestational hypertension. As the disease worsens, some people may develop preeclampsia and eclampsia.