It shows the fetal growth and movements; whether the amniotic fluid is enough, whether the placenta functions adequately; and whether the bloodstream to the fetus and placenta is sufficient.
Also, some abnormalities that can be identified at the 3rd trimester can be diagnosed by this ultrasonography.
This ultrasonography is particularly important for the pregnant women who have experienced problems with their pregnancy, pre-eclampsia, diabetes, stillbirth, and fetal growth deficiency.
With the same USG device, the resistance of flow in the uterine arteries is assessed (uterine artery Doppler) to see the potential pre-eclampsia, preterm delivery, risk for a fetus with growth deficiency, and whether the risk of complication for that pregnancy is increased. This procedure can also be performed at any period of pregnancy. It is important to perform it even during the early months of pregnancy and fetal screening at 11 to 14 weeks, which will be easier and earlier. A closer monitoring is recommended when the resistance is identified high during this Doppler measurement. In addition, a low dose of aspirin and omega 3 supplement can be advised depending on the gestational characteristics.
Umbilical artery Doppler ultrasound is a widely used assessment method. It assesses the flow in the 2 arteries of the umbilical cord. It is particularly used at the 3rd trimester of risk pregnancy to determine wellbeing of the fetus. A normal umbilical artery Doppler means a normal blood volume to the fetus and normal oxygen in the fetus blood.
Blood flow in other vessels of the fetus can also be assessed in some specific cases, such as fetus growth retardation, lack of gaining weight, and anemia or transfusion between the twins. These vessels include the middle cerebral artery in the fetus brain, the ductus venosus or aorta between the heart and the liver.
Kavak ZN, Alin Başgül Yiğiter, Prenatal diagnosis of Fetal Malformations by Ultrasound and Color Doppler, Atlas of fetal abnormalities, Donald School Atlas of Fetal anomalies, ed. A. Kurjak, FA Chervenak, JM Crrera, Jaypee brothers medical publishers, New Delhi 2007, Chapter 18, pp 247–274.
Alin Başgül Yiğiter, ve Z.N. Kavak, “Prenatal Diagnosis of Fetal Abnormalities by Ultrasound and Color Doppler”, Gynaecol Perinatol,15,3, 149–156 (2006).
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