Today, in the diagnosis of fetal malformations and normal pregnancy disorders, modern equipment is increasingly being used to look at the problem from the inside out. The ultrasound apparatus is widely used in the diagnosis and analysis of diseases and conditions of the human body. Such studies are closely integrated into medical practice and are practically indispensable in the process of observation and treatment. For pregnant women, in addition to the usual study, an ultrasound of the fetus with dopplerometry is prescribed. This is a common practice for any medical center.
Dopplerometry
Throughout the entire period of bearing a baby, a woman is prescribed studies with an ultrasound device. At different stages of pregnancy, fetal dopplerometry is prescribed to conduct research and prevent developmental disorders. Dopplerometry is one of the types of ultrasound that is usually done in the last months of pregnancy, usually in the third trimester.
The study of blood flow in the central arteries of the fetus, uterus, and placenta makes it possible to assess the speed of blood flow and the condition of the main vessels, as well as the umbilical arteries, which ensure the vital activity and nutrition of the fetus. To carry out such a study, a special nozzle is needed. As a rule, an ultrasound with dopplerometry is performed in conjunction with the main one or can be prescribed as a separate, additional study by the attending physician.
Appointment of ultrasound with doppler
Dopplerometry allows you to determine the exact size, diameter and location of the main arteries of not only the fetus, but also the placenta, umbilical cord, uterus of the woman, the speed of blood flow through the vessels, and also makes it possible to timely detect the presence of any violations or extinction of the function of the placenta, which may be a harbinger various complications both during pregnancy and during childbirth. Therefore, the importance of such a study should not be underestimated. So, timely dopplerometry of the fetus, decoding of its indicators allow timely prophylaxis, alleviate the condition and prevent possible risks.
Indications for Dopplerometry
Dopplerometry as an additional study must be prescribed if the following diseases are found in a pregnant woman:
- Gestosis.
- Hypertonic disease.
- Kidney disease.
- Diabetes.
Also, fetal dopplerometry can be prescribed for early detection of developmental disorders, congenital malformations, developmental delays, oligohydramnios, the possibility of premature maturation of the placenta, abnormalities in the structure of the umbilical cord or congenital chromosomal pathologies, severe forms of heart defects, etc.
Doppler study of the uterine arteries
Dopplerometry of the uterine arteries makes it possible to assess the condition of the vascular system of the uterus, placenta, and interciliary space. The formation of the interciliary space occurs during embryo implantation, approximately one week after conception. Blood circulation in the uterus of a woman is carried out with the participation of two arteries: ovarian and uterine. Even during the formation of the placenta, some changes occur in the walls of these arteries, which subsequently lead to their growth and expansion in parallel with the growth of the placenta. Thanks to this process, the utero-placental blood flow is formed to the complete formation of the placenta and increases 10 times.
Dopplerometry of the uterine arteries allows you to evaluate the functioning of the spiral arteries, the formation of which ends by the beginning of the 3rd trimester. With complications during pregnancy, not all arteries have physiological changes, so they do not expand and do not grow during placenta growth. Thus, the arteries become unable to provide sufficient blood circulation and blood supply to the placenta, which can lead to its death or deficiency of nutrients, oxygen. This, in turn, can lead to detachment of the placenta, miscarriage and miscarriage.
Dopplerometry: decryption
When conducting a Dopplerometric study, a graphical image of the blood flow velocities through the arteries during each cardiac cycle, which differ in systolic and diastolic, is displayed on the screen of the ultrasound device. In order to further understand what is at stake, we will make a transcript:
- Systole is the pressure that occurs when a heart muscle contracts.
- Diastole is the pressure that occurs when the heart muscle relaxes.
So, for one heart beat, there are indications of systolic and diastolic pressure in the arteries. Each vessel under study has its own norms and characteristic typical blood flow velocity curves.
To assess the norms and indicators of blood flow, the following indices are used:
- Systolic-diastolic ratio.
- Heart rate index.
- Resistance index.
The systolic-diastolic ratio, the pulse index and the resistance index reflect the state of the main arteries and aorta and blood flow in them, which is the purpose of such a study as dopplerometry. Norms and deviations from them reflect different types of impaired fetal development, determine the pathology associated with the effect of blood flow on gestation. So, the doctor can assess the functioning of the placenta, its viability, providing the fetus with oxygen reserves through the umbilical cord, as well as possible malformations in the fetus associated with circulatory disorders and diseases of the heart muscle.
Dopplerometry: norms
To evaluate the results of the Doppler study, special value tables are used. They indicate all the permissible norms of fetal dopplerometry for three indicators:
- Systolic-diastolic relationship.
- Resistance index.
- Heart rate index.
Similar studies should be carried out in all pregnant women, but this is especially important for those who are at risk and have problems with blood circulation or hereditary defects.
Dopplerometry of the fetal vessels and an ultrasound examination are prescribed for a period of 23 weeks of pregnancy. During this period, this procedure is very relevant for assessing the risk group for complications and malformations of the placenta, which can lead to termination of pregnancy. But such studies can be carried out from 13 weeks to the end of pregnancy. Each week has its own dopplerometry indicators. All these studies are conducted to study the three main arteries: the umbilical cord arteries, the uterine, and the fetal aorta.
The systolic-diastolic ratio, starting from the 20th week of pregnancy, should be 2.4 or less.
The resistance index is calculated for the arteries of the umbilical cord, uterine, as well as the middle cerebral. The norm is:
- for uterine - less than or equal to 0.58;
- for the umbilical artery - less than or equal to 0.62;
- for the middle cerebral artery of the fetus, the index should be less than or equal to 0.77.
Already in the second half of pregnancy, these indicators are almost unchanged. And by the end of the period of gestation, the systolic-diastolic ratio should not exceed two units.
Value Display
Dopplerometry of the fetus in the 3rd trimester studies the blood flow and contributes to the implementation of early diagnosis, the appointment of prevention of placental insufficiency, treatment of gestosis with characteristic changes in arterial blood flow in the uterine vessels. When a decrease in the average diastolic value is detected, the systolic-diastolic ratio increases significantly, and, accordingly, the remaining indices calculated on its basis also increase.
With dopplerometry in the second and third semester of pregnancy, specialists pay particular attention to the umbilical arteries. The study of the blood flow curves of the central umbilical artery takes on importance after the tenth week of pregnancy. In this case, the diastolic aspect of the blood flow may not be detected until the 14th week. In a fetus that has chromosomal abnormalities, reverse diastolic blood flow is usually recorded for 10–13 weeks.
In uncomplicated pregnancies, the systolic-diastolic ratio does not exceed three units on the curve representing blood flow. The pathology of fetal development is characterized by a decrease in the final diastolic rate until its complete disappearance.
By the fifth and subsequent months of pregnancy, the most significant diagnostic indicators are studies of fetal blood flow. First of all, the aorta is examined, as well as the middle cerebral artery. The values of these blood flows are characterized by high systolic thresholds for pressure changes in the aorta, often accompanied by a decrease in diastolic parameters. The smaller they are, the higher the risk of pathologies. The most unfavorable situation is the zero value of the diastolic component.
For the middle cerebral artery, clinical changes in the blood flow can be accompanied, on the contrary, by an increase in the diastolic component, which, in turn, is a manifestation of cerebral hyperperfusion or indicates the development of fetal hypoxia.
When studying the speed of blood flow in the venous ducts, systolic peaks occupy a large part of the percentage area of the curve and are at the same level without sharp drops; dips to the diastolic component of short duration periodically appear. Thus, the whole curve is almost homogeneous without sharp peaks. If high peaks of the systolic component or disappearance of diastolic pressure are indicated , then this may indicate a chromosomal pathology of the fetus, as well as the onset of fetal hypoxia.
The accuracy of Doppler ultrasound is about 70%. The most effective is the study of utero-placental and fetal-placental blood flow, which can almost completely diagnose various disorders.
Assessment of the results of the study
According to the assessment of different indices, blood flow disturbance indicators are divided into various degrees:
- Grade 1 is a violation in the utero-placental blood flow with unchanged fetal-placental blood flow or a violation of the fetal-placental blood flow with unchanged uterine-placental.
- Grade 2 is a one-time change and violation in both types of blood flow, the indicators of which do not reach any critical values, but they do exist.
- Grade 3 is the presence of critical violations in the indicators of fetal-placental blood flow, regardless of the presence of changes or even a slight violation of the uteroplacental blood flow.
Indications for the appointment of Doppler
Dopplerometry of the fetus can be prescribed once or twice during the course of the entire pregnancy as a planned procedure. Sometimes it is prescribed more often. This occurs if there are risks or pathologies of the development of the fetus or the condition of the uterus and placenta requires it. There is a list of indications in which the passage of a Doppler study is simply necessary and necessary:
- If the mother’s age is more than 35 or less than 20 years (early or late pregnancy).
- Polyhydramnios and oligohydramnios.
- On a previous study, an ultrasound device revealed cord entanglement.
- The development of the fetus lags behind the established norms.
- The mother has chronic severe illness.
- When previous pregnancies ended in miscarriages or children were born with severe defects or stillbirths.
- If there is a suspicion of malformations.
- With multiple pregnancy.
- If the mother has a negative Rh factor, which can cause fetal rejection in case of circulatory disorders.
- With unsatisfactory CTG parameters.
- If there has been a trauma to the abdomen pregnant.
If there is a threat of abortion, a Doppler study is necessary to determine the causes of such concerns. In this case, the woman goes to a day hospital, where the first thing she does is a Doppler ultrasound examination and takes hormone therapy to preserve the pregnancy until the time at which it is possible to conduct a safe delivery with minimal risk.
Study preparation
To prepare for a Doppler examination of a pregnant woman, it is advisable to take food a couple of hours before visiting the ultrasound room and then be limited to only water. To start the study, you will need to lie on a couch near the apparatus on your back, while opening your stomach from chest to groin. One or several drops of a special conductive gel, which helps the penetration of the ultrasonic signal, are applied to the surface of the abdomen of the pregnant woman, and a special sensor is applied, which smoothly drives the surface of the abdomen.
Dopplerometry of the fetus can be performed both on black-and-white equipment, and on modern color equipment, on which an ultrasound specialist will see curves with peaks indicating the intensity and norm or deviation from it of blood flow in the arteries. After the study, the doctor will enter the data obtained during the examination, and write a transcript to them, after which he will issue a Doppler ultrasound in the hands of the pregnant woman.
Dopplerometry of the fetus, indicators and their decoding will be a good help for the obstetrician-gynecologist in managing a woman's pregnancy, preparing for safe delivery and controlling complications. Monitoring the state of internal organs and the fetus with the help of Doppler research is greatly simplified and has been proving its effectiveness and reliability for many years. More and more studies conducted in recent years confirm the safety of the examination using ultrasound technologies, eliminating the possibility of harming the health of both the expectant mother and the unborn baby.