Doppler ultrasonography (or Doppler) is an instrumental method of ultrasound diagnostics of the blood supply system in the uterus, umbilical cord and fetus during pregnancy, which is based on the Doppler effect. The essence of the method is that the ultrasound waves of a special transducer with a changed frequency are reflected from objects moving in the bloodstream (i.e., blood cells). This change in frequency is proportional to the speed of movement of the targeted structures.

Why is blood flow examined during pregnancy?

During pregnancy, the third circle of blood circulation in the female body is formed – the placental circulation. The supply of oxygen and nutrients to the fetus and uterus depends on the efficiency of the uteroplacental blood flow.The results of the study allow us to judge the state of uteroplacental-fetal blood flow and indirectly indicate the intrauterine condition of the child (whether the child receives enough oxygen and nutrients, whether it is not lagging behind in development). Without this test, it is impossible to accurately assess the structure of the fetal heart.

20 – 24 and 28 – 32 weeks of pregnancy are the recommended periods for Doppler ultrasonography

Indications for Doppler ultrasonography:

Before conception:

The procedure helps the obstetrician-gynecologist, based on the analysis of the current state of the blood vessels of the reproductive system, to prevent the following pathologies in the future: spontaneous abortion, frozen pregnancy, miscarriage, fetal growth retardation.

After conception:

• Fetal size discrepancy with the gestational age;
• severe preeclampsia, fetoplacental insufficiency, abnormal amount of amniotic fluid, premature maturation and other pathological conditions of the placenta, etc;
• maternal diseases (changes in arterial pressure, diabetes, kidney disease, etc.).

Does Doppler ultrasound harm the fetus?

Doppler ultrasonography is a very important diagnostic procedure that helps the doctor identify various abnormalities in fetal development and assess the health status of a pregnant woman.

In addition, Doppler ultrasonography is the most informative diagnostic method at 33 weeks of pregnancy, since conventional ultrasound diagnostics will not show a complete picture of the health of the unborn baby and mother.

It is strongly recommended to follow the instructions of the obstetrician-gynecologist when referring for Doppler ultrasonography.

Factors requiring the appointment of Doppler ultrasonography:

• The mother has chronic diseases
• Presence of pathology during previous pregnancies
• Detection of fetal heart abnormalities, heart rhythm disturbances on a routine ultrasound
• Diagnosis of Galen’s vein aneurysm
• The presence of congenital malformations of the respiratory system in the fetus
• Placental growth
• The presence of one artery in the umbilical cord
• Risk of developing a rhesus conflict

What is examined during Doppler?

1. Blood circulation in the fetal vessels
2. Features of uterine arteries and veins
3. Hemodynamics in the middle cerebral arterial vessel
4. Blood flow rate in the venous duct

Blood flow is assessed by a number of indicators:

Resistance index

To obtain the index, the difference between the minimum and maximum speeds is determined. The final figure is divided by the maximum.

Diastolic and systolic ratio

The ratio of blood flow velocity in the vessels in the two phases of diastole and systole is estimated.

Ripple index

For this assessment, the difference between the minimum and maximum velocities is divided by the average hemodynamics.

Evaluation of pathological processes detected by Doppler ultrasonography

Based on the data obtained after Doppler ultrasonography, the specialist of ultrasound diagnostics at the IVMED Family Source clinic diagnoses possible hemodynamic disorders during pregnancy, which are divided into 3 degrees of severity:

I “A”

impaired hemodynamic parameters at the level of uterine arterial vessels

I “B”

pathological changes in hemodynamics in the umbilical cord arteries

II

hemodynamics is disturbed in the umbilical cord and uterine arterial vessels

III

zero / reversed hemodynamic values in the diastolic phase in the umbilical cord arteries (accompanied by a terminal fetal condition and requiring immediate delivery)