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Types of ultrasound for pregnant women. When an ultrasound is done to determine the fact of pregnancy: how they prepare and what it shows in the norm, an error. Definition of pregnancy by ultrasound

ultrasound during pregnancy

This section contains a whole series of articles that cover all the necessary information. There are articles here that relate not only to determining the sex of the unborn baby, in what ways this can be done, but also what kind of research is being done in such an important period of women's lives. If you are wondering when an ultrasound is performed and what it shows, then you are in this section. Research during pregnancy must be planned and not abandoned, as it is completely harmless and safe. Ultrasound helps to identify pathologies in the early stages of pregnancy and, if necessary, either provide assistance or terminate the pregnancy.

Ultrasound in late pregnancy is equally important. Also, in parallel with ultrasound during pregnancy, other examinations are carried out, such as:

  • ECHO KG fetus
  • Biochemical screening
  • Cervicometry
  • Screening
  • Doppler

You can also find out why ultrasound can be wrong with determining the sex of the child and what can affect this. This section also provides information on survey standards.

If you are just planning a pregnancy, then you need to read a number of articles about the corpus luteum, which provide detailed information about what it is, what its role is and what pathologies of the corpus luteum exist. If you still have any questions, please consult your OB/GYN.

The corpus luteum is considered an integral and important element so that a woman can become pregnant and bear a child in the first weeks of pregnancy. To determine its presence and size, it is necessary to undergo an ultrasound examination. An ultrasound examination is prescribed only after a preliminary consultation with a gynecologist and if there are indications. The size of the corpus luteum As for the size of this temporary gland, they can ...

Ultrasound examination during pregnancy is a mandatory procedure, which is carried out as planned in each trimester and corresponds to its term. An ultrasound examination helps to determine the pathologies and the correct development of the fetus at different stages of pregnancy. Most mothers are concerned about the question of whether it is possible to determine the sex of the child ahead of schedule and whether ultrasound can make a mistake in determining. It is worth saying that...

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During pregnancy, women need to undergo a lot of examinations and tests in order to observe how the fetus develops, as well as to detect pathology in a timely manner and begin treatment. Most pregnant women are interested in whether certain studies, including biochemical screening, pose a danger. In this article we will try to understand the issue related to biochemistry. What's happened...

It has already entered our lives so tightly that it is even used to study an unborn fetus. One of the unique and indispensable properties of this method is the ability to use ultrasound to determine pregnancy.

The absolute harmlessness, painlessness and simplicity of the procedure allows women to learn about conception at the earliest possible date, find out the sex of the unborn child, and for doctors it has become indispensable for monitoring the course of pregnancy. At the same time, the procedure provides detailed information about the state of the female reproductive system.

When will pregnancy be visible on ultrasound?

Given the small size of the fertilized egg, in order to diagnose pregnancy during an ultrasound examination, you need a successful match of several components:

  • A sufficient gestational age for the developing embryo, which so far looks like the smallest “tubercle”, to become not only noticeable, but also distinguishable from other formations in the uterus.
  • The mucous membrane of the uterus should not have inflammation, since swelling develops as a result, and the embryo, in order to be able to determine it, must be larger, that is, a later development period.
  • The best option for a diagnostic method is that the doctor must prescribe exactly the type of procedure that is able to determine the presence of an embryo or its absence.
  • Higher requirements are imposed on the ultrasound machine for determining pregnancy - it is necessary to use high-resolution devices.
  • The examination is carried out by a specialized obstetrician-gynecologist, who specializes in determining pregnancy in the early stages.

Only in the case of a combination of all these factors, the fact of conception will be diagnosed, and the doctor will prescribe the expectant mother to undergo further necessary measures. Then when should a woman who is suspected of being pregnant go for an ultrasound scan in order to minimize the likelihood of a doctor's mistake?

In most cases, with sufficient qualifications of the sonographer and the availability of modern equipment, ultrasound diagnostics will show an embryo with a diameter of 3-5 mm, so you can find out about pregnancy if your period is delayed by 5-6 days. Such a delay will approximately equal 3-4 weeks of pregnancy.

An image taken during an ultrasound at 3–4 weeks of gestation

Reference . The most informative first ultrasound will be at a 10-day delay if it is performed vaginally. In addition, you should know that for such a short period of time the doctor will not be able to detect the presence of an ectopic pregnancy, but only to suspect the pathological attachment of the fetal egg.

What methods are used?

Ultrasound diagnostics has several varieties that allow you to conduct an examination of a particular organ with maximum accuracy. So what kind of ultrasound is done to determine pregnancy? Depending on the indications, the doctor may choose a transvaginal or transabdominal method. Transvaginal ultrasound is performed using a special probe that is inserted into the vagina. This method allows you to get as close as possible to the uterus and the embryo developing in it and diagnose the presence of pregnancy for 3-4 weeks, and sometimes even at an earlier date.

Transabdominal ultrasound is performed by a standard technique in which the doctor drives the emitter along the lower part of the abdominal cavity, where the female reproductive organs are located - the uterus, ovaries and fallopian tubes. Due to the relatively distant location of the sensor from the uterus, pregnancy can be detected two weeks later, when the embryo has already reached a larger size. With this method, conception will be diagnosed at approximately 5-6 weeks.

And if a woman is obese or there is a significant accumulation of fat on her stomach, then pregnancy on ultrasound can be considered at a later date. In some situations, when, for example, there is damage to the vagina and it is impossible to perform the procedure transabdominally, transrectal ultrasound can be prescribed - which is done through the rectum. But this approach is rarely used.


The main differences in the types of ultrasound of the female reproductive organs

Preparatory activities

Ultrasound of the pelvic organs, performed to determine conception, needs some preparation. In order to obtain the most accurate information about the structure of the uterine cavity and fallopian tubes during the procedure, the patient should take care to reduce gas formation in the intestines. Since gas bubbles can interfere with the inspection and lead to a distortion of the research results.

To reduce flatulence in the colon, it is necessary to start dieting 3-4 days before the study. Such a diet involves the exclusion of foods that contribute to the occurrence of flatulence. These include legumes, raw vegetables and fruits, sweets, muffins and bakery products, fatty cheeses, meat, fish, first courses cooked in fatty broths, dairy products, with the exception of low-fat cottage cheese.

Prohibited drinks are strong tea, coffee, alcohol, carbonated drinks and water. The patient's diet should be made up of low-fat types of meat and fish, first courses on their broths, boiled vegetables, low-fat cottage cheese. On the day you can use no more than one boiled egg and a glass of kefir or milk. Meals should be small, but frequent, so that the food has time to be digested and evacuated from the stomach and intestines, without stagnation, causing fermentation.

Important! Before the procedure, you should refrain from smoking for several hours, which causes increased secretion of the digestive tract, as well as from chewing gum and sucking on lollipops, as this contributes to the swallowing of air. Such preparation is also necessary for transabdominal and transvaginal ultrasound, but the drinking regime immediately before the procedures is strikingly different.


Foods to Avoid When Preparing for a Pelvic Ultrasound

In a transabdominal examination, sufficient bladder filling will be required to improve visualization of the pelvic organs. To do this, you can use two methods - refrain from urinating 3-4 hours before the procedure, or drink about a liter of water about an hour before the examination and do not empty the bladder.

Transvaginal ultrasound, on the contrary, does not need to fill the bladder, since the doctor has the opportunity to examine the organs in close proximity and a full bladder will only interfere with the examination. In addition, even a slight movement of the emitter into the vagina can cause a strong urge to urinate, creating discomfort for the patient. Therefore, she needs to visit the toilet and empty her bladder before starting the procedure.

The procedure for performing the procedure

The definition of pregnancy by ultrasound in a transvaginal way is performed with an empty bladder. It is optimal if the patient empties it almost before the procedure itself. The subject is asked to release the lower part of the pelvis and genitals from clothing, and lie down on the couch with legs bent at the knees. The doctor puts a condom on the ultrasonic emitter (for hygiene purposes) and inserts it into the vagina.

The procedure is not accompanied by pain, since the diameter of the sensor does not exceed 2–3 cm. Such a diagnosis makes it possible to determine conception from the 5th day of delayed menstruation. Transabdominal ultrasound is even easier to do. The patient will only need to lift or lower the clothes from the lower abdomen so that the diagnostician has sufficient access to the uterus. During the procedure, the doctor will examine the projection of the reproductive organs, choose a comfortable position and angle for the best visualization.

By the same principle, a 3d ultrasound is performed to diagnose conception, and it will be effective in terms of detecting pregnancy already on the 7-10th day of the absence of menstruation.

When to get an ultrasound to confirm pregnancy?

The doctor will send the woman to do an ultrasound in case of a delay in menstruation, and if the test shows a weak second strip. But before the examination, he will prescribe a blood test for a hormone called chorionic gonadotropin (CG), and the patient is advised to remember the indicator of its level. This information may be needed for subsequent examinations.

Also, the procedure will be required if the next menstruation is delayed, a positive test, but if at the same time the doctor does not see the main signs of pregnancy at the gynecological examination. Another indication is pain of a different nature in the lower abdomen. An ultrasound examination will become mandatory with a delay of 1.5–2 weeks or more (small deviations of 5–7 days are considered normal), and after that bloody or brownish discharge of any volume appeared.

How many times is it done?

The harmlessness and information content of ultrasound examination allows it to be carried out several times over the entire period of gestation. In an uncomplicated pregnancy, as a rule, a woman undergoes it three times at 12-13 weeks, 22-23 and 31-32.

Such a study of the state of the mother and fetus ensures the control of its development, the timely detection of possible pathologies and the development of further tactics of therapeutic measures. At 12-13 weeks, ultrasound provides an opportunity to assess the anatomical characteristics of the embryo, to find out the thickness of the collar zone - the main indicator that helps to identify Down syndrome.

Also at this time, the first blood test is done. At 22–23 weeks, with the help of ultrasound diagnostics, the presence of anomalies in the development of the brain, cardiovascular system, stomach, intestines, liver and kidneys is established. At this stage, it is possible to exclude previously identified or suspected malformations of the fetus.


Determination of Down syndrome is an important task of screening ultrasound

In addition, after 20 weeks, it becomes available to determine the sex of the child, so many parents are looking forward to this period, knowing that the likelihood of a doctor making a mistake is already negligible. An examination at 31–32 weeks helps to detect late developmental disorders of the heart and other internal organs. With it, the growth rate of the embryo is studied, and the compliance of its size with the norm.

Despite the fact that ultrasound does not have any negative effect, doctors still try not to abuse this study. For almost 40 years of its use, not a single case of harm to the fetus has been identified, but it is better not to risk it. Therefore, in most cases, the first ultrasound is performed no earlier than 10–12 weeks, when it is already possible to visualize the rudiments of systems and organs.

In addition, the procedure performed by the transvaginal technique increases the risk of spontaneous abortion. Based on these considerations, establishing the fact of conception is done only according to strict indications, and the desire to simply get checked out or take the first photo for the album of the future baby is not such.

Most Frequently Asked Questions

During the use of ultrasound diagnostics to confirm the fact of pregnancy, categories of issues that most concern future parents have already been formed. These include the following.

Why does the test show conception, but ultrasound does not?

There may be several such situations:

  • Early visit for examination - you must wait at least 5 days after the delay of menstruation. And this is the case if the procedure is carried out through the vagina.
  • There is a development of pregnancy outside the uterus, so it is not visible. In this situation, you should not panic, but take a referral for an analysis to the level of hCG. The indicator should be at least 1000 IU / l. Then it is necessary to retake the analysis in a couple of weeks - during pregnancy for a period of 4–5 weeks, the level will rise to 5,000–30,000 IU / l.
  • There is an additional source that provokes the production of this hormone, as a result of which a second band appears in the test. The cause may be a cystic drift (pregnancy pathology) or liver neoplasms. Then a second ultrasound is prescribed and the study of the level of hCG in dynamics.

The lack of visualization of the embryo at the 7th obstetric week is a sign that if there was a pregnancy, then it does not develop.

When will an ultrasound visit be most informative?

The best time to visit the ultrasound room is considered to be the 5th gestational week, which equates to 20-22 days from the delay of menstruation. Of course, it is possible earlier, but there is a high probability that the diagnostician may make mistakes with the establishment of conception.

At an earlier date, when a fetal egg is found, it cannot be concluded that it is developing, since there is a pathology - anembryogeny, in which only membranes are present in the fetal egg, and the embryo itself is not. At week 5, the fetal heart begins to contract, and this can be tracked by the vaginal method, and by the abdominal method at 6-7 weeks. A later and more thorough examination of the heart and blood vessels is carried out from 24 weeks using ultrasound.

Where to get a diagnosis to determine conception?

This procedure is best done not in offices or clinics engaged in multidisciplinary activities, but in family planning centers, antenatal clinics or on the basis of maternity hospitals. This is due to the extensive experience and qualifications of doctors specializing in this particular type of diagnosis.

Pregnancy involves a wide range of examinations aimed at studying the health of a woman and the unborn child, as well as identifying possible malformations in the fetus and predicting the upcoming birth. Therefore, it is extremely difficult for modern obstetrics and gynecology to do without ultrasound diagnostics. The level of medicine is constantly growing, at the same time, the equipment and qualifications of doctors are being improved, which makes ultrasound even more informative and safe. There are various types of ultrasound during pregnancy, which make it possible with one hundred percent probability to calculate its real terms, determine the localization of the embryo and identify violations in its development.

Planned and additional examinations

Any pregnant woman must undergo, which is also called screening. They are held during all trimesters and have specific goals. If a pathology is detected in both the mother and the fetus, the doctor may prescribe additional functional and laboratory examinations.

Screening ultrasound

The first screening ultrasound during pregnancy corresponds to the end of the first trimester and is very important, since during it the fetus is visualized for the first time. At this time, organs and systems are already actively formed.

The main objectives of the procedure are listed below.

  • Determination of the number of fruits and their localization. The condition of the amniotic membranes is also assessed, and in the case of multiple pregnancy, special attention should be paid to the number of placentas. This will help differentiate monozygotic twins from dizygotic twins.
  • Establishment of the obstetric gestational age and the expected date of delivery.
  • Evaluation of the structure of the umbilical cord and the correctness of the stages of placentation.
  • Exclusion of signs of chromosomal aberrations. If a child has Down's syndrome, a thickening of the collar space, a violation of the transtricuspid blood flow, and blurred boundaries of the nasal bones can be detected. Such indicators should force a gynecologist to refer a woman to a geneticist.
  • Identification of other fetal anomalies from the heart, kidneys, etc. Exclusion of signs of detachment of the placental membrane or the threat of spontaneous miscarriage.

The second fetal ultrasonographic examination is performed in the second trimester of pregnancy and also has its own special tasks:

  • confirmation of the obstetric term;
  • determination of the type of presentation and position of the unborn child;
  • gender determination;
  • assessment of the functional state of the placenta, as well as its localization;
  • counting the amount of amniotic fluid;
  • assessment and measurement of the length and width of the cervical canal during pregnancy (important to exclude isthmic-cervical insufficiency);

During this period, an ultrasound examination of the fetal brain structures is also performed. During the procedure, anomalies in the development of the cerebral hemispheres are excluded, the lateral ventricles are visualized, as well as their choroid plexuses. The diencephalon and occipital fossa are examined. The research itself is carried out sequentially, that is, from top to bottom.

The third trimester corresponds to the last scheduled ultrasound examination. Together with this diagnosis, color and are performed, assessing the state of blood flow and cardiac activity of the fetus.

With the help of the final ultrasound, you can:

  • detect anomalies in the structure of organs and systems;
  • clarify the nature of the presentation and the position of the unborn child and exclude the possible entanglement of his umbilical cord;
  • calculate the relative weight of the fetus and its body length;
  • to compare the size of the child and the gestational age at the time of compliance;
  • evaluate the function, thickness, density, maturity and echostructure of the placental membrane;
  • measure the volume of amniotic fluid;
  • in women with a history of caesarean section, measure the thickness of the scar on the uterus.

All the data obtained will help you choose the right tactics for the upcoming birth and minimize the risks.

Selective methods

Additional ultrasound examinations are prescribed if a woman has disturbing complaints (bleeding from the genital tract, intense pain in the lower abdomen), an exacerbated or aggravated chronic underlying disease. Also indicated are:

  • lack of fetal movement for a period of 20 weeks;
  • discrepancy between the gestational age and the size of the uterus;
  • premature labor activity;
  • pathological presentation (frontal, facial, foot).

Pregnancy as a result of IVF does not do with three procedures.

Ultrasound at the 5-7th week is advisable to carry out if an ectopic pregnancy is suspected, which in case of late diagnosis is often complicated by perforation of the fallopian tube, profuse uterine bleeding, up to hemorrhagic shock.

Doppler ultrasound technique in the period of 20-23 weeks is carried out in the case of:

  • pyelonephritis, diabetes mellitus in a pregnant woman;
  • development of late gestosis (hypertension, preeclampsia, etc.);
  • multiple pregnancy;
  • previous pathological pregnancies;
  • Rhesus conflict;

Types of ultrasound according to the method of obtaining data

Modern ultrasound equipment is equipped with a large number of various functions and capabilities, which makes the study highly informative and reliable. Depending on the methods of obtaining data, the following types of ultrasound during pregnancy are distinguished:

  • Doppler mapping;

2D method


Most often, the antenatal clinic conducts a 2D examination, during which a two-dimensional flat image is obtained. This method is based on the visualization of the uterus and fetus in two dimensions, or planes: in length and height. The result is a black and white 2D echo image.

It is prescribed for:

  • confirmation of the fact of pregnancy and clarification of its terms;
  • exclusion or confirmation of multiple pregnancy;
  • determination of placenta attachment;
  • assessment of the state of amniotic fluid;
  • studies of the nature and speed of blood flow in the vessels of the placenta, umbilical cord, fetus and the uterus itself;
  • counting the child's heart rate, assessing his motor activity;
  • timely detection of deviations in development.

3D method

The three-dimensional volumetric image allows the doctor to more carefully evaluate the echographic data of the fetus and give a more accurate prediction regarding the course of pregnancy and childbirth. At the same time, during the study, it is possible to examine in detail the facial features of the unborn child and facial expressions, to see what movements he makes.

Three-dimensional diagnostics is recommended for a period of 12-28 weeks, since in the later period of pregnancy the motor activity of the fetus decreases and in most cases it fits snugly against the back wall of the uterus, which will interfere with obtaining a clear image.

Compared to a simple ultrasound for pregnant women, more accurate data are obtained on the thickness of the cervical fold, and defects such as a cleft lip or cleft palate are well visualized. From the 14th week, you can determine the sex of the baby.

There are three modes of 3D ultrasound examination method:

  • mixed;
  • surface;
  • skeletal.

The first is used only as a guide. The superficial one allows to identify malformations of the facial skeleton. The third reveals the features of bone development, symmetry, structure and length of the phalanges, spinal column, etc.

4D method


An ultrasound that gives a three-dimensional image in dynamics is called a 4D method. In its essence, it practically does not differ from the previous one, however, the echo picture is obtained in time, that is, in the form of a video film.

The doctor also sees in detail:

  • facial features of the child;
  • his facial expressions;
  • movements of the arms and legs.

All this can be recorded on a carrier, which is in great demand among pregnant women.

Doppler method

The method is based on the ability of liquid media to reflect high-frequency ultrasonic waves. For example, shaped elements act as a reflecting force in blood vessels.

The technique allows assessing the direction of blood flow, its speed and amplitude. Therefore, the state of the walls and lumen of the vessels is analyzed. The movement of fluid towards the transducer is colored red (arteries), and blue - away from the transducer (veins). Thanks to Doppler mapping during pregnancy, the pathology of the vascular bed, the presence of aneurysms and blood clots are excluded.

KTG

Normally, the first cardiotocography is performed at a period of 32 weeks, as well as 1-2 times during the following weeks and directly during the birth itself. It is rather difficult to overestimate the method, since with its help, the contractile activity of the uterus and the cardiac activity of the fetus are recorded on a special film for 40 minutes.

After evaluating the obtained indicators, the obstetrician-gynecologist can confirm or exclude hyper- or hypotension of the uterus and, most importantly, fetal hypoxia, which can be caused by various pathological conditions (preeclampsia, cord entanglement, premature detachment of the placenta, steal syndrome, etc.).

How is the diagnosis carried out

Ultrasonography during pregnancy can be performed in two ways, each of which has its own advantages and disadvantages.

Transabdominal examination

For its passage requires little preparation, aimed at preventing excessive accumulation of gases in the intestinal tube. Thus, a woman follows a light diet for three days, from which the following are removed:

  • bread;
  • legumes;
  • chocolate;
  • fresh fruits;
  • milk;
  • vegetables.

Also, about an hour before the procedure, the bladder should be filled with liquid (1-1.5 liters of water are drunk).

The method is non-invasive and painless, since the sensor is installed on the skin of the abdomen in its lower part. The transducer is pre-lubricated with a special transparent gel. The examination is performed in several planes to obtain the most voluminous and accurate echo picture.

Transvaginal examination

In this case, it is also recommended to follow a diet, but there is no need to fill the bladder. A disposable protective condom is put on a special vaginal sensor, together with which the transducer is inserted into the vaginal cavity with gentle movements (no more than 5-6 cm). Due to the fact that the uterus and the fetus are close enough, the image is clearer.

Ultrasound- these are sound waves that are not audible to the human ear and are in the range of frequencies above 20,000 Hertz. In medicine, it is often used for diagnostic purposes to obtain information about human tissues and organs, while the frequency range from 1 to 20 MHz is mainly used. To study the condition of the fetus during pregnancy, ultrasound has been used since the 60s of the last century, however, as a general express examination, covering more than 85% of pregnant women, it has become widespread only since the 80s - 90s of the 20th century.

Ultrasound during pregnancy poses a challenge non-invasive method(bloodless, that is, when the human skin and tissues are not affected by needles or surgical instruments) in utero examine the fetus and its associated structures.

The method allows obtaining information about the structure and condition of the fetus with a certain accuracy at each specific point in time, and is also affordable, informative and relatively safe for women and children, which determined its use as a screening. To date, ultrasound screening allows diagnosing more than 90% of malformations in utero.

The effectiveness of ultrasound as a study that allows you to identify most of the defects at the prenatal stage is determined by:

  1. Qualification of ultrasound diagnostic doctors (for prenatal(antenatal) examination, the doctor must be retrained in this field and work in the center of prenatal diagnosis);
  2. Terms of research (should be the same in all institutions of the country);
  3. Venue (should be held in a prenatal center, since the antenatal clinic does not have specialists and equipment of the proper level);
  4. The equipment must be of an expert class;
  5. Unified ultrasound protocol;
  6. Unified accounting of congenital and hereditary pathology;
  7. Liaison with pathological services for possible verification(confirmation) of an ultrasound diagnosis in the event of a subsequent termination of pregnancy;
  8. Uniform protocols and terms of examination of born children.

Information In addition to monitoring the condition of the fetus during pregnancy, it may be necessary to study the work of organs and systems of a pregnant woman. Then ultrasound is also prescribed, for example, of the thyroid gland, abdominal organs, heart, etc.

When to do an ultrasound during pregnancy?

By order of the Ministry of Health of the Russian Federation No. 457 “On improving prenatal diagnosis in the prevention of hereditary and congenital diseases in children”, a three-time screening ultrasound:

It is possible to establish the presence of pregnancy and determine the location of the fetal egg by ultrasound from 2.5-3 weeks of pregnancy (approximately from 5-7 days of delay). In the early stages, it must be remembered that there is a “false” fetal egg during an ectopic pregnancy (that is, when the pregnancy is actually outside the uterus, and an ultrasound is determined by a formation similar to a fetal egg in the uterine cavity). When it is established that the fetal egg is in the uterine cavity, the gestational age is determined. More precisely, it is established when the embryo is already visualized (most accurately from 7 weeks). This examination also determines the number of embryos. From 5 weeks of pregnancy, you can see a heartbeat, which indicates that the baby is alive.

The study of the place of attachment of the fetal egg to the wall of the uterus allows you to detect placental abruption, which is especially important in the presence of pain and bloody discharge from the genital tract. Keep in mind that selection data points to . Sometimes the so-called fetal wash syndrome(the presence of spotting on the days of the expected menstruation without signs of detachment with a live and viable fetus).

Important It is important to examine the uterus for anatomical features (eg, bicornuate, saddle) because abnormal attachment of the ovum (eg, in the horn) may require termination of pregnancy due to possible serious complications.

When conducting an ultrasound during pregnancy, it is also determined in which ovary the corpus luteum(formation that produces progesterone, allowing the embryo / fetus to grow and develop until the placenta is fully formed), as well as the presence of ovarian cysts. They require control in the first trimester, as surgical treatment may be required, which is carried out mainly in the period of 16-18 weeks of pregnancy.

Is ultrasound harmful?

In a diagnostic study, the ultrasonic sensor works as a source of impulses for only 0.1% of the time of the entire study, the remaining 99.9% it works to receive impulses. That is, for only one thousandth of the time, the sensor transmits energy to the tissues under study. In this case, the ultrasonic wave can have the following effects on the surrounding tissues:

  1. thermal(i.e., tissue heating). Overheating of tissues greatly affects the bone tissue.
  2. non-thermal(cavitational - the formation of bubbles). In this case, destruction of surrounding tissues is possible.

Ultrasound used in diagnostics does not cause tissue damage in normal 2D mode due to its low power. But it must be remembered that each study (especially for the fetus) should be carried out strictly according to the indications, using techniques that minimally affect the fetus. The physician must adhere to the principle ALARA(As Low As Reasonably Achievable - as low as reasonably achievable), that is, each specialist must understand the capabilities of the device, but use them when the benefit from the information received exceeds the possible harm.

On many devices, to reduce the possibility of a detrimental effect on tissues, indicators are set:

  • Thermal index(warns of possible overheating of tissues during the study). This index is especially important in the study of bone tissue (the second and third trimester of pregnancy - the study of the bones of the skull, spine, limbs of the fetus), since it is most susceptible to heating.
  • Mechanical index(This index evaluates non-thermal processes in tissues during ultrasound - cavitation, which can cause potential tissue damage).

There are no data on the dangers of ultrasound diagnostics. Studies on humans, and even more so on pregnant women, have not been conducted. Therefore, in order to minimize even hypothetical harm during ultrasound, specific tasks should be set before ultrasound, which will reduce the time of its implementation. And dopplerography, ultrasound should be carried out if it is impossible to obtain information with a conventional two-dimensional study.

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