Pregnancy is an unforgettable time for a woman. During this wonderful and difficult period, the expectant mother experiences many different emotions and experiences, including those associated with fear for the health of her baby.
During pregnancy, a woman has to undergo many examinations, the purpose of which is to provide the most complete information about the condition of the fetus. One of these studies is cardiotocography (CTG). This is a rather informative method for assessing the state of a baby's cardiac activity. What is CTG and what are the indications for conducting it? At what stage of pregnancy is it most advisable to start this study? Let's figure it out in order.
Method essence
Based on historical experience, we can safely say that the cardiovascular system of a child in the mother's womb for a long time it has been the subject of detailed study of doctors:
- By itself, the registration of fetal heartbeats made it possible to determine exactly whether he was alive or not.
- The study of the main indicators of a child's cardiac activity could give, to one degree or another, a broad idea of the functional abilities of his cardiovascular system.
Already at the beginning of the 19th century, obstetricians could auscultate the belly of a pregnant woman, where the heartbeats of her baby were clearly audible. Over the next two hundred years, doctors did not stop looking for more and more advanced methods of examining the expectant mother and her child, which would make it possible to assess the state of his cardiovascular apparatus with the greatest degree of accuracy. One of these rather informative diagnostic methods is cardiotocography, or CTG.
CTG is performed on a pregnant woman primarily for an objective assessment of the functioning of the fetal heart muscle.
In addition, this method of instrumental diagnostics makes it possible to determine the frequency of contractions of the child's heart, the level of his motor activity, as well as the dynamics of uterine contractions.
Usually CTG is performed in combination with dopplerometry (a type of ultrasound examination, which makes it possible to record the main indicators of the level of blood flow in the vessels of the fetus, uterus and placenta) and ultrasound. This approach makes it possible to fully understand the state of the child's cardiovascular system, as well as to record structural or functional disorders of its development in the early stages, which largely determines the outcome of further therapy.
Cardiotocography allows you to identify the following pathologies of intrauterine development in a baby:
- hypoxia (lack of oxygen);
- intrauterine infection;
- insufficient or excessive volume of amniotic fluid;
- fetoplacental insufficiency (a combination of structural and functional disorders in the development of the fetus or placenta, which can lead to premature birth, the formation of various abnormalities in the development of the fetus or oxygen starvation);
- violations of the development of the organs of the cardiovascular system of the fetus;
- placental abnormalities, etc.
This study is carried out using a special apparatus, which consists of a pair of sensors that output the obtained readings to a recording device. The first sensor (ultrasonic) registers the fetal cardiac activity, and the other (tensometric) - the activity of the uterus and the corresponding reaction to it of the baby. Both of them are attached with special belts to the woman's belly.
When is CTG performed?
The most optimal time for the first CTG is 32 weeks of pregnancy, provided there are no special indications. The Ministry of Health at the legislative level has secured the right to conduct this study on a pregnant woman as early as 28 weeks.
For special indications, the attending physician may prescribe CTG earlier than the officially established period, however, in such a case, the study will only register the baby's heartbeat. It will not be possible to determine his reaction to the contractile activity of the uterus, as well as changes in the performance of the heart muscle, depending on the change in the position of the fetus at a given period of pregnancy. This is due to the fact that until the 28th week of pregnancy there is no well-established functional connection between the heart and the autonomic nervous system of the fetus.
For each gestational age, there are diagnostic indicators of the norm, indicating the normal development of the fetal cardiovascular system.
Any deviations from the accepted criteria, depending on the specific situation, can be regarded by the attending physician as evidence of the presence of pathology of intrauterine development.
Cardiotocography is not considered the main type of instrumental examination of the state of fetal health, which can largely determine the tactics of pregnancy, therefore, in the absence of special indications, CTG is performed no more than twice during the entire third trimester.
There are a number of pathologies of pregnancy and associated complications, in the presence of which more frequent CTG is indicated. These include:
- post-term pregnancy - this study is carried out once every 4 days after the expected date of birth;
- excessive volume of amniotic fluid, established heart disease, fetoplacental insufficiency, presence of thyrotoxicosis in a pregnant woman (excessive production of thyroid hormones) - CTG is performed at least once a week;
- multiple pregnancy, hypertension, clinically narrow pelvis, infectious lesion of the urogenital system - 3 times a month.
Ultimately, the right to determine the timing and frequency of CTG belongs to the attending physician. It will be based on the characteristics of the course of pregnancy, the woman's history, as well as the results of other diagnostic studies.
Carrying out before childbirth
Cardiotocography may be prescribed at the onset of labor.
If the gynecologist has not finally determined the main tactics of labor management, then he can resort to this diagnostic procedure, based on the results of which he can choose the most appropriate algorithm for a particular situation. In this case, CTG is carried out more often than the deadlines established by law (even daily).
If the doctor decides on the management of childbirth naturally in the case of a prolonged pregnancy, then the sequence of his actions during CTG is as follows:
- The study is carried out on the day of the planned birth or a day later.
- The next CTG is done 5 days later, if the results of the previous study were satisfactory.
- After the same period of time, CTG is repeated.
If, after 41 weeks of pregnancy, childbirth does not occur, the attending obstetrician-gynecologist may reconsider the proposed management of labor. He can decide on the stimulation of labor or operative delivery.
One way or another, to make such a decision the results of the performed cardiotocography have a direct impact, since they show the current state of the child quite informatively.
Normal indicators of CTG
Whatever the results of cardiotocography, they cannot be an absolute basis for making a particular diagnosis. CTG data are capable of displaying only the current state of the fetus, therefore, to compile a more complete clinical picture, this diagnostic procedure must be repeated several times.
CTG data are displayed in the form of a curve, thanks to which it is possible to determine a number of discrepancies with normal indicators characteristic of a particular gestational age.
When decoding a cardiotocogram, specialists take into account the following parameters:
- Basal rate is the average number of heartbeats over a given period of time.
- Rhythm variability is the average level of deviation from the previous parameter.
- Deceleration - a decrease in the number of heartbeats over a certain time. On the cardiotocogram, they look like sharp depressions.
- Acceleration - an increase in heart rate. On the cardiotocogram, they look like teeth.
- Tokogram - shows the level of activity of the uterus.
According to the method of taking indicators, there are several types of CTG:
- Non-stress test - registration of data on the child's cardiac activity is carried out in the most physiological conditions for him.
- Fetal movement - this is where fetal movements are recorded when the uterine tone changes.
- Oxytocin test - for carrying out such a diagnostic manipulation of a pregnant woman, oxytocin (a substance that stimulates the contractile activity of the uterus) is not administered, while CTG notes the fetal response to contractions.
- Mammary test - uterine contractions are triggered by stimulating a woman's nipples. This method is the most preferable in comparison with the previous one, as it has fewer risks to the fetus.
- Acoustic test - various kinds of sound stimuli are used, and after that, the device records the response of the fetus.
Preparation measures for CTG
Like many other methods of instrumental diagnostics, cardiotocography requires some preparation.
For the research data to be sufficiently informative, it is necessary that the fetus is in an active state. To do this, you can go to the pool or walk directly before the diagnostic procedure.
The easiest way to "stir up" a baby is to tickle the belly. The main thing in trying to provoke the activity of the fetus is not to overdo it, so as not to harm him or yourself.
The most appropriate time for this diagnostic manipulation is the period from 9:00 to 14:00 and from 19:00 to 00:00.
CTG should not be taken on an empty stomach or within 1 hour after a meal or glucose administration. Failure to comply with these simple rules can lead to the appearance on the cardiotocogram of a large number of errors that "lubricate" the real idea of the state of the fetus. In this case, most likely, the procedure will have to be repeated.
Is it capable of doing harm?
Conducting CTG during pregnancy, regardless of the total number of procedures, does not pose any threat to the condition of a woman and her baby. This diagnostic manipulation does not have any contraindications. Therefore, the fears of some expectant mothers associated with a possible threat from CTG are absolutely groundless.
It is important for every pregnant woman to remember that this type of research is quite informative, and in certain situations it is absolutely necessary. Therefore, one should not be led by one's own unreasonable fears and not based on anything prejudice. Use common sense and the advice of your healthcare professional.
A complete clinical picture of the baby's health is based on a set of instrumental diagnostic measures, where CTG is one of them.
For how cardiotocography (CTG) is done, see the next video.
