How to assess the condition of the fetus
Doppler measurements measure the resistance to blood flow in the umbilical cord arteries: an increase in it indicates that the placenta is coping worse and the fetus is receiving less oxygen. A study of blood flow in the uterine arteries shows how fully the restructuring of the uterine vessels has occurred - disturbances here are associated with the risk of preeclampsia and fetal growth restriction. In case of pronounced changes, the middle cerebral artery of the fetus is additionally assessed: redistribution of blood flow in favor of the brain is an important sign of compensation for hypoxia. Indications: fetal growth restriction, maternal hypertension and preeclampsia, diabetes mellitus, multiple births, complicated obstetric history. It is Doppler ultrasound that often determines the timing and method of delivery.
Why are timing screenings needed?
It is no coincidence that ultrasound examinations during pregnancy are carried out at certain times: each window shows its own signs. At 11–14 weeks, the thickness of the nuchal translucency and nasal bone are assessed - markers of chromosomal abnormalities that later disappear. At 18–22 weeks, the formation of organs allows for a detailed examination of the anatomy of the fetus. In the third trimester, the main things are growth, fetal position, condition of the placenta and blood flow.
Missing the screening window means losing information that cannot be obtained at another time.
What is being assessed
- heart rate, number of fetuses and gestational age
- fetometry - dimensions and compliance with deadlines
- anatomy of organs and identification of malformations
- localization, structure and maturity of the placenta
- amount of amniotic fluid
- blood flow in the arteries of the umbilical cord, uterus and fetal vessels
Security
Ultrasound during pregnancy has been used for more than half a century and is recognized as safe when used for medical reasons. International recommendations advise not to conduct research without indications solely for the sake of photos or videos, and also to limit the duration of exposure - the principle of reasonable sufficiency.