Doppler ultrasound is an ultrasound diagnostic method that allows you to determine the state of blood flow in the mother-placenta-fetus system. During pregnancy, this study makes it possible to timely identify placental insufficiency, prevent the development of fetal hypoxia and other complications associated with impaired uteroplacental blood flow.

The essence of the method

The effect, used in modern obstetrics to determine the speed of blood flow in vessels, was discovered by the Austrian mathematician Christian Doppler in 1842. The researcher was able to calculate the variability of the frequency of sound waves depending on the speed of the selected object. In this case, we are talking about changing the speed of blood flow through the vessels of the uterus, placenta and umbilical cord. The Doppler effect is actively used not only in obstetrics, but also in other areas of medicine.

Blood flowing through the vessels moves at different speeds during systole (the contraction phase of the heart) and diastole (the relaxation phase). This can be detected using a special ultrasound device. The ultrasonic wave emanating from the sensor is immediately reflected on various objects. If the selected object is stationary, then the reflection of the ultrasonic wave returns to the device with an unchanged frequency. If an object is in motion, the frequency of the wave changes. The difference between the frequency of the outgoing and incoming waves is the ultrasound shift used during the study of blood flow.

For obstetricians, the speed of blood flow in the following vessels is important:

• uterine arteries;
• umbilical cord arteries;
• fetal middle cerebral artery;
• fetal aorta;
• umbilical cord veins.

Using an ultrasound machine, a doctor can calculate the speed of blood flow in the vessels of interest and promptly detect various hemodynamic disorders. During pregnancy, a study of blood flow in three vessels is required:

• left uterine artery;
• right uterine artery;
• umbilical cord arteries.

In most cases, this is enough to determine the state of blood flow in the mother-placenta-fetus system and identify various hemodynamic disorders. The study of other vessels is carried out according to indications and only in the presence of certain pathological changes in the uterine arteries or umbilical cord arteries.

Why is Doppler ultrasound needed?

Doppler testing during pregnancy is performed on all women at the prescribed time. Only this study allows us to accurately determine the state of blood flow in the mother-placenta-fetus system. This system is unique and lasts only 40 weeks of intrauterine life. Adequate blood flow in the placenta, uterine arteries and umbilical cord ensures normal fetal development throughout pregnancy.

Why is it so important to know the level of blood flow in these vessels? The thing is that it is this parameter that largely determines the very possibility of maintaining pregnancy and giving birth to a healthy child at the time prescribed by nature. The state of hemodynamics determines whether the pregnancy will continue for the entire 40 weeks or be terminated at any stage. The state of blood flow also affects a woman’s well-being. With hemodynamic disturbances, the risk of developing gestosis and other serious complications of pregnancy increases significantly.

There are several stages in the formation of such complications. It all begins in the very early stages of pregnancy, at the moment of implantation of the fertilized egg into the wall of the uterus. Inadequate implantation leads to a delay in the development of blood vessels and the formation of primary disorders of the uteroplacental blood flow. At this stage, the pregnancy may be interrupted and a miscarriage may occur at up to 12 weeks.

If pregnancy continues, vascular development continues in accordance with the laid down program. The problem is that the formed vessels will be defective and will not be able to fully perform their function. Primary placental insufficiency develops. The baby does not fully receive the oxygen and nutrients necessary for its development.

Inadequate formation of the uterine and placental arteries is dangerous not only for the child, but also for the pregnant woman herself. Against this background, the body does not adequately adapt to pregnancy. This condition is one of the leading causes of the development of preeclampsia, a serious complication that can lead to the death of a woman and child in late gestation.

Indications

Doppler ultrasound during pregnancy is carried out within strictly defined periods:

• 18-21 weeks;
• 32-34 weeks.

The first time Doppler ultrasound is performed simultaneously with the second ultrasound screening. Conducting the study at an earlier date is not advisable. The final formation of the uterine arteries occurs only at the beginning of the second trimester. The process is completed at 16-18 weeks of pregnancy. After this, you can draw any conclusions about the state of blood flow in the uterine arteries and the performance of the placenta.

It is important to remember: in 30% of healthy women, the development of the uterine arteries is completed only at 22-25 weeks of pregnancy. In this regard, a single disturbance of blood flow at a period of 18-22 weeks should not be regarded as a serious threat to the development of the fetus. With moderate changes in the uterine arteries, the expectant mother is monitored. Blood flow is regularly monitored using Doppler ultrasound, and the condition of the fetus is assessed using ultrasound. In most women, blood flow normalizes after 22 weeks without additional drug intervention.

Such tactics are not permissible in cases of severe blood flow disturbances, as well as in cases of identified pathology in the hemostatic system (hypercoagulable shifts). In this case, individual therapy is selected taking into account the duration of pregnancy and the severity of hemodynamic disorders. Blood flow monitoring is carried out every 2-3 weeks.

Doppler safety

The issue of the safety of ultrasound and Doppler testing is especially acute for pregnant women. Fearing harm to their baby, some expectant mothers refuse such an important study, thereby exposing the child to no less risk. Is this tactic justified?

At the moment there is no consensus on this issue. Most obstetricians and gynecologists claim that Doppler ultrasound is relatively safe for a woman and her baby. The possible harm from ultrasound waves in the second half of pregnancy is doubtful, while the benefits of such a study are enormous. In this regard, experts strongly recommend that all expectant mothers undergo screening tests at the scheduled time of gestation.

Doppler testing is mandatory in the following situations:

• gestosis;
• delayed fetal development (by ultrasound);
• post-term pregnancy;
• pathology of amniotic fluid (polyhydramnios or oligohydramnios);
• multiple pregnancy;
• Rh sensitization;
• chronic diseases of the mother (hypertension, kidney pathology, autoimmune diseases, diabetes mellitus and others).

If indicated, the doctor may prescribe an ultrasound and Doppler ultrasound at any stage of pregnancy.

How is the procedure performed?

No special preparation is required for the study. Doppler testing is performed by the same doctor who does the screening ultrasound. The procedure takes place in a specially equipped room with the woman lying on her back. A gel is applied to the abdominal area to improve the conduction of ultrasonic waves. The doctor runs a sensor over the expectant mother’s abdomen, measuring the speed of blood flow in the vessels of the uterus and umbilical cord.

The whole procedure lasts no more than 10 minutes. In the later stages of pregnancy, many women find it difficult to spend such a long time on their back. Compression of the inferior vena cava leads to shortness of breath, a feeling of lack of air, and rapid heartbeat. In this case, you can turn on your side for a while and then return to your starting position.

Types of Dopplerometry

Color Doppler mapping

Recently, color Doppler mapping (CDC) has been actively used in obstetric practice. This is a special Doppler method in which different blood flow rates are highlighted in different colors. CDC is a more visual method that allows you to obtain reliable information about the state of blood flow in the arteries of the uterus and umbilical cord.

CDC is actively used for the diagnosis of trophoblastic disease (hydatidiform mole). With this pathology, instead of a normal embryo, a tumor is formed, which is dangerous to the health and life of the woman. The malignant form of trophoblastic disease can lead to the death of a woman. The tumor is well supplied with blood, and colorectal dosage allows an accurate diagnosis to be made at the earliest stages of the disease.

Doppler echocardiography

Doppler echocardiography is a method that allows you to assess the level of blood flow in the fetal heart. The study is carried out during pregnancy using a special ultrasound sensor. The method is recognized as the most promising in the diagnosis of some serious developmental defects.

Indications for Doppler echocardiography:

• fetal growth retardation syndrome;
• abnormalities of the heart;
• heart defects;
• heart rhythm disturbances;
• abnormalities of the umbilical cord vessels;
• some malformations of the lungs, kidneys, and abdominal organs.

Interpretation of results

When performing Doppler sonography, three indicators are assessed:

• uteroplacental blood flow;
• fetal-placental blood flow;
• blood flow in the vessels of the umbilical cord.

Uteroplacental blood flow is determined in two uterine arteries (left and right). The speed of blood flow through the uterine arteries determines the viability of the placenta and shows how well this organ copes with its functions. Violation of uteroplacental blood flow can lead to the development of gestosis and deterioration of the fetus.

Fetal-placental blood flow shows the speed at which blood flows to the fetus. If blood flow in this section is obstructed, the baby does not receive enough nutrients and oxygen. This condition leads to the development of chronic hypoxia and fetal growth retardation.

Blood flow in the umbilical cord vessels directly depends on the speed of blood flow in the uterus and placenta. If there are existing disorders in these organs, the movement of blood through the arteries and veins of the umbilical cord will also suffer.

To assess blood flow in the mother-placenta-fetus system, the following indicators are used:

• resistance index (RI);
• systole-diastolic ratio (SDO = S-D);
• pulsation index (PI).

The resistance index is calculated using the formula:

IR = (S-D)/S.

C – maximum speed of blood flow in systole.
D – maximum blood flow velocity in diastole.

IR is calculated in several cardiac cycles at once, after which its average value is displayed.

The pulsation index is calculated using the formula:

PI = (S-D)/M, where M is the average blood flow speed.

Normal Doppler values ​​are presented in the table:

The speed of blood flow depends on the duration of the actual pregnancy. If the gestational age was determined incorrectly, the data obtained may be unreliable. The interpretation of the results should be carried out by a doctor.

Disturbances detected by Doppler measurements

Normally, blood flow in the uterine arteries and umbilical cord vessels should be adequate for the duration of the actual pregnancy. The degree of deviation of blood flow velocity from the proposed norms allows us to judge the severity of the condition of the woman and fetus in a specific period of time.

There are three degrees of blood flow disturbance:

• IA degree – violation of uteroplacental blood flow while maintaining fetal-placental blood flow.
• IB degree – violation of fetal-placental blood flow while maintaining uteroplacental blood flow.
• II degree – simultaneous disturbance of both uterine and fetal blood flow.
• III degree – critical disturbance of blood flow (zero or retrograde blood flow).

The doctor’s further tactics will depend on the degree of blood flow disturbance:

IA or IB degree

The expectant mother should be under the supervision of a doctor. Hospitalization is usually not required. Every 5-7 days, blood flow is monitored using Doppler ultrasound. According to indications, an ultrasound is performed to assess the condition of the fetus and identify possible developmental delays. After 32 weeks, CTG (cardiotocography) is performed to determine the fetal cardiac activity and detect early signs of hypoxia.

Violation of the uteroplacental or fetal placental blood flow is a reason for additional examination. This pathology often occurs with disorders in the hemostatic system. Increased blood clotting provokes a change in blood flow in the placenta, vessels of the umbilical cord and uterus, which ultimately leads to delayed fetal development. If there is a degree 1 blood flow disorder, you should donate blood for a hemostasiogram (extended coagulogram).

II degree

In degree II, both uterine and fetal blood flow are affected. Treatment in this case is carried out in a hospital. As basic therapy, drugs are used that improve hemodynamics and the functioning of the placenta. If disturbances in the hemostatic system are detected, blood thinning agents are added to treatment.

Blood flow monitoring is carried out every 2 days. If the condition of the woman and baby is satisfactory, it is possible to prolong the pregnancy. If signs of severe fetal hypoxia appear, emergency delivery is performed. In case of II degree of blood flow disturbance, independent childbirth is not always possible. In many cases, a cesarean section is performed after short preoperative preparation.

III degree

In case of III degree of blood flow disturbance, early delivery is usually carried out, regardless of the stage of pregnancy. Conservative therapy in such a situation makes little sense. Prolongation of pregnancy is possible only in a hospital setting with constant ultrasound monitoring and fetal support with medications. In most cases, such pregnancies end in premature birth.

Any disruption of blood flow in the mother-placenta-fetus system is a reason for additional examination and treatment by a specialist. With timely treatment, it is possible to maintain pregnancy until the due date and give birth to a healthy, full-term baby.

What is fetal Doppler - this is a subtype of ultrasound diagnostics that allows you to evaluate the characteristics of blood flow in the vessels of the child, uterus and placenta. Based on this study, the doctor can judge whether the baby is suffering from a lack of oxygen or not. It is also established at what level the vascular pathology occurred (in the uterus, placenta or umbilical cord).

This diagnosis is carried out after the final formation of the placenta (later 18 weeks). They do it according to indications.

For the patient, it feels no different from standard ultrasound diagnostics.

When do pregnant women need Doppler ultrasound?

This examination can be carried out 1-2 times during pregnancy as a routine examination, along with a “mandatory” ultrasound. If the following cases occur, fetal Doppler must be done as soon as possible:

1. The age of the expectant mother is more than 35 or less than 20.
2. Low water.
3. Polyhydramnios.
4. The umbilical cord loops wrap around the neck or are located close to it (according to ultrasound).
5. The child is developmentally delayed.
6. The mother suffers from severe chronic diseases: diabetes, thyroiditis, lupus, vasculitis, hypertension.
7. The previous pregnancy had a bad “ending”: miscarriage, birth of a child with defects, death of the intrauterine baby.
8. If there is a suspicion of a malformation of an internal organ.
9. During multiple pregnancies, especially when the children differ greatly in size.
10. If the mother is Rh negative and has Rh antibodies in her blood.
11. If CTG parameters are unsatisfactory.
12. Doppler testing is also performed after an abdominal injury to a pregnant woman.

Preparing for the study

Dopplerography of the fetus does not require preparation. A pregnant woman simply comes to the ultrasound room, preferably a couple of hours after eating.

She does not need to fill her bladder or follow a specific diet before the test.

How is Doppler testing performed?

You need to lie on the couch on your back or left side, opening your abdomen from the sternum to the pubis for examination.

A drop of a special gel is applied to the stomach, along which the ultrasonic sensor will move.

A color picture will be displayed on the screen, in which different shades of red will indicate blood flow directed towards the sensor, and different shades of blue will indicate blood flow directed away from the sensor.

In this case, a more intense color will indicate a higher blood flow rate.

Analysis of research data

The results of Doppler sonography are assessed by an obstetrician who monitors the woman's pregnancy. This is done based on several indicators:

• resistive index (RI): the ratio of the difference between systolic and minimum (diastolic) blood flow velocities and its maximum value
• pulsation index (PI): the ratio of the difference between the maximum and diastolic speeds of blood flow through a given vessel to the average speed
• the ratio of blood flow velocity through a vessel in systole and diastole (SDO - systole-diastolic ratio).

Read also:

Detailed details of ultrasound at 10-11 weeks of pregnancy

Each of these indicators is assessed for each type of artery. Thus, fetal ultrasound with Doppler is designed to assess blood flow in the umbilical and uterine arteries, as well as in the carotid and cerebral arteries of the fetus, and its aorta. Based on a comparison of the obtained numbers with normal ones, a conclusion is made as to whether the child suffers from a lack of oxygen or not.

Table of norms and indicators

The norms for fetal Doppler monitoring are the following indicators.

1. SDO in the arteries of the uterus: from the 20th week until the end of pregnancy it should be about 2.0.

2. SDO, IR and PI in the umbilical cord artery decrease gradually throughout the second half of pregnancy. There may not be a diastolic component of blood flow in this vessel until the 14th week. Such a characteristic of blood flow as “reverse” or “reverse” at 10-13 weeks indicates the presence of chromosomal abnormalities in the developing baby.

3. In the second half of pregnancy, it is also important to evaluate the same indicators for the baby’s aorta. Thus, the SDO in it is considered normal:

• 16-20 weeks: 6.1-6.75
• 20-23 weeks: 5.4-6.1
• 23-26 weeks: 4.85-5.24.

In this case, IR is about 0.75 in the aorta.

4. SDO in the middle cerebral artery also decreases depending on the duration of pregnancy: if at 23-26 weeks it is about 0.9, then at the end of pregnancy it should be 0.66-0.8.

Norms for the last trimester

Doppler monitoring of the fetus in the 3rd trimester is represented by the following indicators:

1. IR in the uterine arteries by week:

• 28-32: 0,34-0,6
• 33-34 weeks: 0.34-0.59
• 35-39th: 0.335-0.57
• 40-41st: 0.321-0.57

2. IR in the umbilical arteries (depending on the duration):

• Week 28: 0.561-0.780
• 29-30 weeks: 0.541-0.77
• 31st-32nd: 0.521-0.75
• 33-34th: 0.5-0.73
• 35-36th: 0.471-0.70
• 37-39th: 0.431-0.68
• 40-41st: 0.41-0.67.

3. PI in the arteries of the uterus: on average, 0.4-0.64.
4. IR in the aortic vessel: on average 0.75. SDO there: about 5.
5. SDO in the middle cerebral artery: 4.4 or more. IR there: 0.76.
6. IR in the carotid artery: 29-31 weeks: 0.74-0.86; closer to 40: 0.65-0.8.

Read also:

What is fetal cardiotography (CTG) during pregnancy?

How to understand how severe fetal hypoxia is

To do this, compare normal Doppler measurements with the obtained result.

1. Thus, an increase in the indicators of SDO and IR in the uterine arteries indicates that the developing baby is not receiving enough oxygen, which may result in a delay in its development.
2. An increase in the same indicators for the umbilical cord artery already indicates feto-placental insufficiency, that is, that the child is already suffering due to vascular pathology. This picture of vascular Doppler also indicates gestosis. And if the IR and SDO in the umbilical cord of one fetus are greater than those of another, this indicates that this baby is suffering (if the numbers for all fetuses are the same, but some are smaller, this is transfusion syndrome).
3. The numbers of SDO and IR in the aorta, which are higher than the normative ones, indicate that the child is not feeling well and needs help. This can be observed in case of post-term pregnancy, and in case of a conflict regarding the Rh factor, and in case of diabetes mellitus in the mother.
4. A decrease (not increase) in IR and SDO during Doppler measurements of fetal vessels such as the carotid and cerebral arteries indicates that this is an extremely serious condition of the fetus. This picture indicates that only its most important organs are supplied with blood to support life. If measures are not taken (usually early delivery), the child will die.

The Doppler effect is based on a change in the frequency of a sound wave depending on the speed of the observed emitter. In our case, it is a change in the frequency of the reflected ultrasonic signal from an unevenly moving medium - blood in the vessels. Changes in the frequency of the reflected signal are recorded in the form of blood flow velocity curves (BVR).

Hemodynamic disturbances in the functional system “mother-placenta-fetus” are the leading pathogenetic mechanism of disturbances in the condition and development of the fetus during various complications of pregnancy. Moreover, in the vast majority of observations, hemodynamic disorders are characterized by the universality and uniformity of changes, regardless of the condition of the fetus and the etiopathogenetic factor.

A change in the normal indicators of FSC is a nonspecific manifestation of many pathological conditions of the fetus, and in many cases preceding the appearance of clinical symptoms, it is important that this also applies to the main pathological conditions during pregnancy - FGR, fetal hypoxia, gestosis, etc. For a period from 18-19 to 25-26 weeks Doppler is the method of choice, because The biophysical profile of the fetus is informative from 26 weeks, but cardiotocography is not yet indicative.

The Doppler technique involves obtaining blood flow velocity curves in the vessels of the utero-placental-fetal blood flow, calculating vascular resistance indices (VRI), and analyzing the results obtained.

Indications for Doplerometry

V.V. Mitkov (1)

1. Disease of a pregnant woman:

Hypertension;

Kidney diseases;

Collagen vascular diseases;

Rh sensitization.

2.Diseases and congenital malformations of the fetus

Inconsistency between the size of the fetus and the gestational age;

Unexplained oligohydramnios;

Premature maturation of the placenta;

Non-immune dropsy;

Dissociated type of fetal development during multiple pregnancy;

Congenital heart defects;

Pathological types of cardiotocograms;

Umbilical cord abnormalities;

Chromosomal pathology.

3. Complicated obstetric history (FGR, gestosis, fetal distress and stillbirth in previous pregnancies).

Vascular resistance indices (ISS)

To assess blood flow velocity curves (BVR), vascular resistance indices have been proposed:

2. Pulsation index (PI, Gosling R., 1975),

(S-D)/avg.

3. Systolic-diastolic ratio (SDR, Stuart B., 1980),

C - maximum systolic blood flow velocity;

D - end diastolic blood flow velocity;

avg. - average blood flow speed (calculated automatically)

SDO and IR are essentially the same thing.

The formula for calculating PI uses the average value of the blood flow velocity, which makes it possible to more accurately assess the shape of the blood flow curve and quantitatively analyze the BSC at zero diastolic blood flow, when SDO and IR lose their mathematical meaning. However, taking into account that in this case (for choosing tactics for managing pregnancy and childbirth) the mere presence of a qualitative change, and not quantitative nuances, is important and that most of the printed research works on Doplerometry in obstetrics were carried out with the calculation of the SDO, then at the moment in In practical work, it is more expedient to use LMS.

A.N. Strizhakov and co-authors proposed a placental coefficient (PC), which allows one to simultaneously take into account changes in both utero-placental and fetal-placental blood flow and reveals a minimal deviation from the normative values ​​of blood circulation parameters in the functional system “mother-placenta-fetus”.

PC=1/(SDO ma +SDO ap)

PC - placental coefficient;

SDO ma, SDO ap - systolic-diastolic relations in the uterine artery and umbilical cord artery.

For some women who are in an “interesting situation,” the doctor may prescribe a procedure such as Doppler ultrasound during pregnancy. But what is it, what is it actually needed for, and in what cases is it prescribed? These and some other questions arise in the mind of every expectant mother. And the first thing that comes to mind is: is such research safe? Let's try to figure this out and much more.

General information

Using a regular ultrasound, the very fact of pregnancy is determined, after which the woman will have to register with the antenatal clinic so that her situation is under constant control. This is a mandatory procedure and is carried out several times throughout the entire period. Ultrasound allows you to assess the condition of the fetus, whether there are any abnormalities.

It is one of the types whose purpose is to determine the state of blood supply between the female body and the child. It is otherwise called Doppler ultrasound (USDG). This research is used not only in the field of obstetrics, but also in gynecology.

With ultrasound, the state of blood flow through the veins and arteries is assessed, that is, its speed, whether there are any abnormalities, and functionality in the placenta. The result of the study is recorded in the Dopplerogram. For specialists in the field of obstetrics, it is important to determine the speed of blood flow through vessels such as:

• Uterine artery.
• Umbilical cord artery.
• fetus
• Fetal aorta.
• Veins of the umbilical cord.

Doppler testing of the fetus allows doctors not only to calculate the speed at which blood moves through the vessels of interest, but also to identify existing hemodynamic disorders. Without fail, during the study, the uterine arteries (left and right) and the umbilical cord arteries are of greatest interest.

This is quite enough to determine the state of the blood flow in the mother-placenta-fetus system, which, in turn, makes it possible to timely identify any disorders. As for the remaining vessels, they are examined under certain circumstances. This may be a detected pathology in the uterine arteries and umbilical cord vessels.

The essence of the technique

The Austrian mathematician Christian Doppler in 1842 discovered an effect that in our time allows us to determine the speed of blood flow in the circulatory system of the human body. It is on this that the principle of operation of Doppler ultrasound during pregnancy is based.

The movement of blood through the vessels is due to the work of the heart. Moreover, during the contraction phase of the heart muscle (systole), it moves at one speed, while during the relaxation phase (diastole), it moves at a different speed.

This can only be detected using a special device called a Doppler. An ultrasonic wave emanates from the sensor, which has the ability to be reflected from objects. If it is stationary, then the wave returns, while maintaining the frequency. However, if the object moves, then the frequency no longer remains constant, but changes. This creates a difference between the outgoing and incoming signals. Therefore, this technique is relevant for determining the speed of blood flow.

Types of Doppler ultrasound during pregnancy

Currently, two main methods are used:

• Duplex scanning.
• Triplex scanning.

With duplex scanning, the strength of blood flow is checked, the condition of the vessels and their patency are taken into account.

Triplex scanning (or, in other words, is practically the same, since the goals are the same. The only difference lies in the fact that with this method a color image is formed. That is, different blood flow speeds are indicated by their hue. Thanks to this, color flow is more in a visual way in which you can obtain reliable information about the blood flow in the main vessels of the female body and the fetus.

Doppler in obstetrics

One can hardly argue with the fact that humanity has now reached certain heights in various areas of activity. And medicine is no exception. Diagnostic equipment is constantly being improved. Take, for example, x-rays - modern devices are characterized by much less harmful radiation. Ultrasound machines have the same indicators.

For many of us, it is important to know how safe they are for health. This especially applies to pregnant women, because they carry a new life under their hearts! Fearing that the study could harm the child, some mothers refuse it. But by this act they expose their baby to no less risk. Is such a decision justified in relation to Doppler testing during pregnancy?

There is no consensus on this matter, although most specialists in the field of obstetrics and gynecology still recommend not to refuse such a study. In their opinion, it is completely safe for both mother and fetus. The harm from ultrasonic waves is doubtful even after the second trimester.

In any case, if we judge the safety of Doppler ultrasound, then this study can pose a threat to the same extent as any other ultrasound procedure.

Dates

At what stage is Doppler testing done during pregnancy? A simple ultrasound, which is a mandatory procedure, is performed as planned or according to medical indications. Doppler testing is prescribed when it is really needed. As a rule, this is the period from the 21st to the 22nd week. This procedure does the following:

• The blood flow of the mother-placenta-fetus system is assessed.
• The position of the fetus in the uterine cavity is determined.
• The risk and degree of umbilical cord entanglement is determined.
• The condition of the heart and main vessels of the fetus is assessed.

It is at this stage of pregnancy that reliable results are obtained, since signs of heartbeat and blood flow can only be detected at this time. However, ultrasound examination can also be performed at later stages of pregnancy: from the 30th to the 34th week. Often, Doppler testing of the placenta during the third trimester is combined with a routine ultrasound procedure.

Medical indications

The need for Doppler testing is determined only by the obstetrician-gynecologist who is managing the pregnancy. The planned timing of this procedure is given above, but there are special medical indications for which additional research is prescribed. These may include:

• Bad habits of the mother such as alcohol and drug addiction, smoking.
• Chronic diseases of the female body.
• Presence of gestosis.
• Autoimmune diseases.
• Multiple births or large baby size.
• Long gestation period.
• Threat of placental abruption.

But in addition to this, Doppler testing is also indicated for Rh-conflict pregnancy. It is carried out again if during the previous study any pathology was identified such as fetal growth retardation syndrome, polyhydramnios, oligohydramnios, etc.

Features of preparation for the procedure

Most pregnant women experience anxiety on the eve of Doppler testing. But this must be avoided, since any such conditions of the mother in a certain way affect the development of the child. Therefore, the first thing you need to do is calm down and pull yourself together - as noted above, ultrasound imaging does not pose any threat to the baby or mother. In addition, the examination is painless and without discomfort.

Is Doppler testing performed during pregnancy under compulsory medical insurance? It is included in the list of mandatory procedures during pregnancy, approved by the Ministry of Health of the Russian Federation. Consequently, such a service will be provided free of charge in public clinics. As for private ones, it is necessary to clarify whether it works in the compulsory medical insurance system and whether a specific examination is carried out there. In this case, Doppler testing will be done free of charge. The procedure itself can go as follows:

• In public medical institutions. You will need a sheet or towel to cover the couch. You can buy disposable diapers at the pharmacy; sometimes they are much more convenient to use than a towel. You also need to take care of paper napkins, which will be needed to remove any remaining gel.
• The study can also be done in any private clinic, where such disposable kits, including napkins, are issued free of charge, since all this is included in the final cost of the procedure itself.

There is no need to adhere to any strict diet. On the eve of the procedure, it is better to refrain from excessive consumption of vegetables and fruits. Gas formation may increase due to coarse fiber, which will significantly complicate diagnostics. Eating a large meal and drinking a lot will lead to the fact that the doctor will not be able to see anything.

About the procedure

Doppler testing is performed in an ultrasound room, and its duration depends on a number of factors. For experienced specialists, this takes 20 to 30 minutes. At the same time, if any pathology is detected, the duration can be increased for obvious reasons.

How is Doppler testing performed during pregnancy? The woman lies down on the couch on her back. But sometimes the doctor will ask the woman to turn on her left side, which is mainly required when the expectant mother is in the third trimester. In this case, the pressure of the enlarged uterus on the inferior vena cava is noticeably reduced.

The ultrasound doctor applies a special hypoallergenic and safe gel to the abdomen. Such products undergo multi-stage testing before use, and only then are they approved for use in pregnant women. The gel has no color or odor, and its consistency resembles thick glue. After this, the doctor picks up a sensor, which touches the surface of the skin of the abdomen. At this time, an image appears on the screen.

The study allows you to assess the state of the three main blood flow systems, on the basis of which the results of Doppler measurements are derived:

• fetal PC;
• uteroplacental BMD;
• fetoplacental PPC.

When studying the BMD, the likelihood of placental insufficiency is determined, while the PPC allows us to identify the severity of this pathology (if any). The PC can be used to judge the child’s condition.

Outcome characteristics

Based on the results of the study, one can judge the speed of blood flow in the body of the expectant mother. For this purpose, vascular resistance indices (VRI) are determined:

• Resistance index (RI or IR).
• Pulsatility index (PI or PI).
• Systole-diastolic ratio (SDR).

RI should be understood as the ratio of the difference between the maximum and minimum blood flow velocities to the maximum velocity value in the compression phase. Its formula: IR = (S-D)/C, where C is the maximum blood flow velocity in the systole phase, and D is the same, only in the diastole phase. The calculation is carried out over several cardiac cycles, and then the average value is determined.

PI is a slightly different ratio: the same speeds, only to the average blood flow speed. Here the formula is slightly different: PI = (S-D)/M, where M is the average blood flow speed.

As for SDO, this abbreviation for Doppler monitoring during pregnancy hides the ratio of the maximum speed in the systole phase to the minimum speed during diastole. Here the formula is simpler: SDO=S-D.

Blood flow disturbance

Doppler testing allows you to diagnose any pathology of fetal development, even in early pregnancy. At the same time, doctors divide them into several degrees depending on the severity of the manifestation:

• IA or IB.
• II degree.
• III degree.

IPC violations are class IA. There are no serious disturbances in the child’s blood circulation, as well as signs of intrauterine growth retardation or fetal development.

Changes to the PPK already belong to class IB. Tellingly, the picture here is the opposite of what is presented above. In other words, there are no pathologies in relation to the BMD, and the violations only concern the communication of the blood vessels of the fetus and mother. Just in this case, there may be signs of intrauterine growth retardation and development of the child.

If, during the interpretation of Doppler measurements during pregnancy, the second degree of severity of the pathology is detected, this indicates the presence of various disorders that affect almost the entire circulatory system of the female body and the fetus. Changes are taking place not only in the IPC, but also in the PPK. Although this state of affairs is more serious, there is no threat to the child’s life yet.

The third degree of blood flow impairment indicates a severe impairment of the child’s blood flow. As a result, the supply of essential microelements is significantly reduced; if no measures are taken, this leads to the death of the fetus. Therefore, with such a diagnosis, emergency medical care is necessary.

Regardless of the degree of pathological change in blood flow, a pregnant woman is prescribed the necessary and special course of treatment. In addition, you will need to undergo Doppler measurements again to observe the progress of changes in dynamics.

Normal indicators

The speed of blood flow is directly dependent on the period of gestation of the child. Therefore, it is important here to correctly determine the actual pregnancy, otherwise the reliability of the research results is called into question. In this regard, only the doctor and no one else should interpret the results. However, only a specialist should also determine the actual duration of pregnancy. In the article you can find a table that shows the indicators of Doppler ultrasound during pregnancy by week.

If the results of the studies do not show deviations from the norm, then the child’s development proceeds without complications, all the necessary nutrients are supplied to him uninterruptedly. However, sometimes there may be slight deviations during Doppler measurements. You shouldn’t be afraid of this, since all this can be easily adjusted if necessary.

As a conclusion

From all this, the only correct conclusion can be drawn: Doppler testing is a fairly reliable and informative diagnosis that allows timely detection of pathological changes in the circulatory system of the female body and fetus. This allows you to make a prognosis for the further course of pregnancy and assess the severity of the pathology. Depending on this, proceed to the necessary measures.

During Doppler testing during pregnancy, it is also possible to detect hypofunction of the corpus luteum and identify other pathological changes that pose a direct threat to the mother and child. For this reason, you should not ignore all the recommendations of the doctor who is managing your pregnancy. Only in this way can many consequences be avoided, and a healthy and full-fledged baby will be born to the delight of the parents!

Pregnancy is a very important stage in the life of any woman. Every expectant mother begins to take care of the health of her baby already at the moment when he is in the womb. Modern medicine makes it possible to monitor the condition of the fetus through examination by a specialist, tests, and various diagnostic methods.

And if everyone knows about ultrasound as a mandatory procedure, then Doppler often remains a blank spot. Ignorance usually leads to a woman refusing this type of diagnosis. What is it really? Is it necessary to do Doppler testing? In what trimester should this additional examination be done? And how to decipher the obtained indicators?

What is Doppler?

Doppler ultrasound is a special type of ultrasound diagnostics that provides the ability to scan and make a detailed assessment of vascular blood flow both in the child and in the mother’s uterus.
The study, like conventional ultrasound, is based on the ability of ultrasound to be reflected from tissues, but with one caveat - the ultrasound wave reflected from moving bodies tends to change the frequency of its own vibrations, and the sensor receives these waves with an already changed purity.

The equipment decrypts the received data - and an image is obtained in color.
This diagnostic method is completely safe for the health of the baby and mother, is highly informative, fairly accessible, has no side effects, is simple and reliable.

Carrying out Doppler measurements

The procedure is not much different from a conventional ultrasound examination. The patient needs to bare her stomach, lie on the couch on her back and relax. Then the diagnostic specialist smears the stomach and a special sensor with a special gel to improve the conductivity of ultrasound, applies it to the woman’s body and moves it over the skin, tilting it at different angles as necessary.

The difference from a conventional ultrasound lies in the “picture” obtained through the study - if traditionally you can see a black and white incomprehensible image on the monitor, then the blue ones are the flow of blood from the sensor. The brighter the color on the screen, the more intense the blood flow.

At the end of the study, the specialist draws up a conclusion based on the analysis of the data obtained and attaches an image, if required. It is worth paying attention to the fact that the diagnostician makes a diagnosis only on the basis of his own research, and the attending physician - taking into account the totality of all examination methods.

Analyzed indicators

Traditionally, the following Doppler measurements are distinguished, based on which the specialist draws up a conclusion:

1. RI (Resistive Index): The difference between the highest and lowest velocity is divided by the highest recorded blood flow velocity.
2. PI (pulsatility index): the difference between the highest and lowest velocities is divided by the average blood flow velocity per cycle.
3. SDO (systolic-distal ratio): the maximum speed of blood flow at the moment of cardiac contraction is divided by the speed during the "rest" of the heart.

Doppler measurements are usually divided by week; the indicators can be viewed in the tables below.

Table No. 1. IR norms for the uterine artery.

Table No. 2. SDO norms for the umbilical artery.

Table No. 3. IR norms for the umbilical cord artery.

Table No. 4. SDO norms for the aorta.

The SDO in the uterine artery should be close to 2.

The PI in the uterine artery is ideally 0.4-0.65.

It is worth noting that the greatest importance is attached, because at this time any deviation from the norm can be fatal, and medical assistance in other cases should be provided immediately.

Help in reading the conclusion

Very often, it is quite difficult to understand the numbers, but even after comparing the obtained indicators with the normal variants, patients ask themselves the question - what does this mean and what are the dangers? To answer these questions you need.

Signs of fetal hypoxia on Doppler ultrasound

High levels of SDO and IR in the arteries of the uterus certainly indicate hypoxia. Increased levels of IR and SDO in the umbilical cord prove the presence of gestosis and vascular pathology. High numbers of SDO and IR in the aorta also highlight the abnormal condition of the child in the uterus; often in this case, the baby needs to receive medical attention. Elevated levels of IR and SDO in the umbilical artery and aorta of the fetus usually indicate Rh conflict, postmaturity, or the presence of diabetes mellitus in the mother.

Low indicators of IR and SDO also indicate a danger to the child’s life. Usually this is a consequence of low blood pressure, which affects only the most necessary organs of the baby. Urgent medical intervention is also necessary to stabilize the condition, otherwise death is likely.

Indicators are especially important during multiple pregnancies, because doctors are interested in whether children receive oxygen equally from their mother. The indicators of SDO and IR in the umbilical cord artery will be higher in the child who ultimately receives less oxygen.

Reasons for testing

This type of examination allows doctors to monitor, as well as in the fetal aorta, cerebral and carotid arteries.

This type of ultrasound diagnostics may seem like a whim, but in fact, the optimal blood supply to the fetus, its oxygen supply, and therefore the timely development of the child in the womb depends on proper blood flow.

Pathologies detected in time using this method are the key to preserving the life of a child. Sometimes, to stabilize the condition of the fetus, it is enough to adjust the lifestyle or take certain medications; in some cases, the intervention of medical personnel may be necessary. But be that as it may, you can only find out about vascular anomalies of this kind.

Of course, Doppler testing is not a mandatory diagnostic method during pregnancy. A woman can do ultrasound diagnostics with Doppler measurements at her own request a couple of times before the birth of the child. However, there are cases in which the attending physician strongly recommends this particular method of assessing the condition of the fetus.

Indications for diagnosis

Ultrasound of twins 10 weeks

First of all, the specificity of this type of examination does not allow it to be carried out, because it is at this time that the placenta is finally formed. At an early stage, such research is simply not informative. Doctors usually recommend diagnosing using this method for the first time (in the second trimester).

But there are also certain indications in which Doppler testing becomes a mandatory step. Typically they are the following:

1. Pregnancy at an early age.
2. The expectant mother is an old-timer.
3. Low water.
4. Polyhydramnios.
5. An ultrasound previously diagnosed an umbilical cord wrapped around the baby's neck.
6. Slow fetal development.
7. Any suspicion of developmental defects in the child.
8. Infectious diseases of the maternal genitourinary system.
9. Some chronic maternal diseases such as diabetes, hypertension, lupus.
10. The presence of several embryos in the uterus.
11. An interrupted previous pregnancy (reasons: spontaneous miscarriage or frozen pregnancy).
12. Developmental defects in previous children, if any.
13. Abdominal injuries of any nature.
14. Rh factor conflict between mother and fetus.

Preparing for the examination

Since such an ultrasound is traditionally performed so as not to harm the baby, no special preparation is required from the pregnant woman. It is enough to carry out the simplest hygiene procedures, as well as visit the diagnostician’s office in a state of calm.

It is important to note that the bladder does not need to be filled, and it is also prohibited to take medications unless circumstances require it.

Is this diagnostic method dangerous?

It has long been proven by experts.

Firstly, ultrasound cannot harm either the mother or the child.

Secondly, ultrasound examination is not fraught with any consequences for the human body.

Thirdly, the abdominal method eliminates possible injuries, as it is as painless and accurate as possible.

Fourthly, Doppler testing itself is possible thanks to a technological breakthrough and depends on the capabilities of the equipment in the diagnostic room, and not on any special manipulations of the doctor, therefore it is also safe.

Pathologies

Traditionally, such an ultrasound makes it possible to track the following anomalies:

1. Oxygen starvation of the fetus.
2. Insufficient oxygen supply to one of the children during multiple pregnancy.
3. Vascular pathologies.
4. Developmental deviation in a child.

What to do after receiving the conclusion?

Comparison of the obtained indicators with the norms and independent decoding are useful skills, especially if you urgently want to know the result of the examination, because we are talking about the child’s health. But in no case should one assume that this information will be sufficient. Moreover, there is no guarantee that you will be able to do this without error.

The ultrasound conclusion with a preliminary diagnosis must be shown to the attending gynecologist, and only he can and has the right to make final conclusions.

It is very important when reading on your own not to take any medications without consulting a doctor!

Is there a possibility of medical error?

Since ultrasound diagnostics is performed by a person, the human factor cannot be excluded. But Doppler testing is still done “in color”, and the probability of error here is extremely small, especially since the examination is performed by a qualified, experienced specialist. Incorrect results can only be obtained with faulty equipment. If the patient has suspicions, she can always have an ultrasound done in another diagnostic room.

Doppler is a very important type of ultrasound diagnostics with expanded capabilities due to the technological revolution in medicine. Such a study allows us to examine the aortas, and therefore the condition of the unborn child, which is not only useful, but also extremely necessary in some cases. Sometimes only thanks to Doppler ultrasound it is possible to detect extremely severe pathologies and react in time to save the life of the baby and even the mother.

Simplicity, accessibility, safety and information content – ​​this is what characterizes this type of ultrasound. Pregnant women should not underestimate the importance of this method. Even in the absence of direct indications for this method, diagnostics should be done with Doppler measurements at least several times during the entire period of pregnancy in order to independently verify the health of your child.