Cardiotocography (CTG) is an assessment method based on recording the heart rate of the tone of the uterus and fetus, which are recorded simultaneously. The study is carried out for all pregnant women if necessary and is characterized by high safety, simple implementation and good information content.
Decoding cardiotocography is no less important than conducting the study itself, because the doctor’s further activities in relation to the pregnant woman depend on the interpretation of the results. CTG should only be deciphered by a specialist competent in this industry. If deviations are detected, he redirects to other analyses, tests and studies that can either confirm or refute the preliminary CTG diagnosis.
How the fetal heart functions: more details
Due to the fact that the heart is considered one of the most important organs, which is also one of the first to form in the embryo, its detailed diagnosis is sometimes mandatory to prevent the development of many congenital pathologies.
For the first time, it is possible to track the heart rhythm approximately at the 5th week of fetal life. This happens through the independent generation of an impulse in the tissues of the heart, which leads to muscle contraction. But at a very early stage, the work of such a muscular organ as the heart in the embryo is not yet subordinate to the nervous system.
How does the device work, what does it show how it works?
A device such as a cardiotocograph provides various types of sensors in the form of:
- Ultrasound (to capture the movement of the heart valves).
- Strain gauge (to fix the tone of the uterus).
- A push-button remote control (or rather, with one button necessary to assess the nature of fetal movements).
From each sensor, when used, the cardiac monitor receives information that records all current changes. This information is also recorded on thermal paper using a special device. The speed and thermal paper of each cardiotocograph are different.
Cardiotocography is carried out with adherence to certain rules both on the part of the specialist conducting the study and on the part of the pregnant woman herself. This is necessary for greater information content. These rules are as follows:
- The CTG recording itself takes about 40 minutes (less time may not be enough to monitor heart rate patterns in detail).
- During diagnosis, a woman should lie on her side, since another position, namely on her back, may imply false final results.
- The sensor that records the fetal heartbeat is installed in the projection of the fetal back. This allows the place of its fixation to correspond to the position of the fetus itself (with an oblique or transverse presentation, for example, it is installed near the umbilical ring, and with a cephalic and pelvic presentation - at a level below or above the navel, respectively).
- A gel is necessarily applied to the sensor itself, which, in fact, improves ultrasound performance.
- The gel is not applied to the strain gauge sensor, but is installed in the area of the uterine fundus.
- The woman is given a remote control, the button on which must be pressed every time the baby moves to establish a connection between his motor activity and changes in heart rate.
How often is CTG done during pregnancy?
It is customary to carry out the first cardiotocography in the 3rd trimester, namely at 32 weeks of pregnancy. Sometimes the study is scheduled at 28 weeks, but not earlier. Some women do not understand why a fetal examination should be performed at such a late stage of gestation, not seeing much point in it. However, only during this period is the baby’s heart rate detected and a relatively smooth sleep-wake cycle is established.
If there are no health problems, the patient should undergo CTG approximately once every 10 days. If special pathologies have been identified in the fetus, special therapy and constant monitoring of the child’s condition are prescribed. The treatment procedure is carried out more often: 1 or 2 times a day.
Indicators
The information content of such a diagnostic method as cardiotocography consists in recording indicators in the form of:
- Variability (shows short-term changes in heart rate and basal rate).
- Basal\main rhythm (considered the main and predominant; it is determined after 30-40 minutes from the beginning of the recording; acts as an average value showing the heart rate).
- Acceleration and deceleration (displays acceleration or deceleration of the rhythm, respectively; the duration of these processes is longer than 10 seconds, and the intensity is more than 15 beats per minute).
Preparation
A diagnostic method such as CTG does not require any special preparatory measures. But, due to the fact that such manipulation lasts 40-60 minutes, moral preparation is still important. To do this, doctors advise you to think about how you can “kill” time during CTG, taking with you, for example, a book or magazine. You should also worry about not feeling hungry or, conversely, a feeling of oversaturation during cardiotocography. It is also necessary to go to the toilet the day before so that these natural desires are not disturbed during the rhythm registration process.
Among other things, it is also important to settle down comfortably so that you can lie in a calm position for a long time. After all, you cannot lie, for example, on your back, as this will likely affect the final diagnostic result.
Advantages of performing CTG at ASTRO
- Experienced doctors are constantly trained and improve their skills.
- Examinations are carried out using modern high-precision expert-class equipment. This allows you to get accurate results in the shortest possible time
- Safety and painlessness of diagnosis.
- No queues. We made sure that any patient could undergo examination at a time convenient for her and without any discomfort
- Opportunities for a quick appointment with an obstetrician-gynecologist. If necessary, the patient can immediately after the examination visit the attending physician to receive the necessary recommendations.
CTG during pregnancy
A good cardiotocogram during pregnancy includes signs such as a basal rhythm of 120-160 beats per minute, absent deceleration, present acceleration (5 or more - for 45-60 minutes during the recording itself), as well as variability of 5-25 beats. min.
But such an ideal picture is quite rare, which is why variants of the norm are allowed for the following indicators: basal rhythm with a lower limit of 110 beats per minute, as well as the presence of single short-term decelerations lasting no more than 10 seconds. in amplitude no more than 20 beats (and after them the heart rhythm should fully recover).
Pathological CTG is considered if:
- there is a lack of acceleration or a slowdown in the rhythm, but the basal one is normal - this is a silent CTG;
- a so-called sinusoidal cardiotocogram is observed, but with a small amplitude - from 6 to 10 beats per minute. (this may indicate fetal hypoxia);
- there is an alternation of accelerations coming after decelerations - this is the Lambda rhythm and in 95% it indicates the presence of compression of the umbilical cord.
In addition, cardiotocography indicators do not always reflect the correct reality regarding the condition of the fetus at the current moment. Even if the nature of the recorded recording seems somewhat alarming due to a short-term disruption of blood flow (due to compression of the umbilical cord vessels by the fetal head), the child himself in the womb will not suffer. Sometimes a different picture is observed when, during prolonged hypoxia, the cardiotocogram displays quite acceptable indicators. As a result, additional studies are prescribed to clarify the parameters of the performed cardiotocography.
The effect of frequent cardiotocography on the fetus
Official medicine does not have data proving the harmful effects of the procedure in question on the child. Sometimes you can hear stories from young mothers that the baby began to behave suspiciously during the study. Experts associate this behavior with the appearance of a new, unknown sound in the “child’s abode,” which may cause slight discomfort in the baby.
In medical practice, there is a low probability of diagnosing pathology in a completely healthy fetus. Such violations are observed under special circumstances:
- sleepy state of the baby at the time of recording the indicators:
- the woman eating too much before the procedure;
- high activity of the child in the womb;
- insufficient amount of conductive gel on the sensor;
- excess weight of the examined patient;
- presence of several fruits.
In the event of a multiple pregnancy, CTG is done more often than usual
One session of cardiotocography averages approximately 800–1300 rubles. But you can often observe a slightly higher price for the procedure, for example, in the Moscow region (1500 rubles) and the Leningrad region (1700–1800 rubles).
The study is carried out in specialized medical centers and hospitals that have the necessary equipment. The specialist conducting the study of indicators must have the appropriate level of qualifications.
CTG during labor
It is important that CTG during pregnancy and during childbirth are two different studies. Because of this, cardiotocography is interpreted differently. This happens due to the fact that contractions, provoking contraction of muscle fibers in the uterus, also provoke spasms of blood vessels, which are localized in the layers of the myometrium. This, accordingly, contributes to a significant deterioration in uteroplacental blood flow, as well as the presence of slight oxygen starvation (hypoxia).
If the birth proceeds normally, then, as practice shows, the child has enough resources to overcome the birth canal. However, in rather extreme situations, the activity of its systems and organs increases and in the pathological condition of the mother, a lack of oxygen is provoked. This condition, being fraught with disruptions in the functioning of the whole organism, contributes to metabolic disorders in tissues and organs. This, in turn, gives rise to irreversible processes and sharply reduces the adaptive capabilities of the fetus.
Note that hypoxia is divided into acute and chronic. With the first, development is observed precisely during the birth process itself. And with the second - during pregnancy. In addition to hypoxia, severe conditions can also manifest themselves in the form of an accelerated heartbeat (ischemia), as well as tissue death of some organs (necrosis).
The norm of CTG during childbirth is manifested in:
- heart rate in the range of 110-160 beats/min;
- the presence of decelerations lasting about 30 seconds, but no more, which occurred after the opening of the cervix by 5 cm or more;
- at least two accelerations, the duration of which is 15 seconds. and more;
- heart rate variability 5-25 beats/min.
Abnormal indicators are manifested in:
- rhythm of 100-170 beats/min;
- its slowdown lasting more than 30 and up to 60 seconds;
- no acceleration for an hour;
- quite low interval.
The CTG technique, being completely safe and harmless, has no contraindications. Its feasibility is determined by the doctor caring for the pregnant woman, based on her individual characteristics. During childbirth, it is required to be carried out in three stages: immediately, as soon as the patient enters the delivery room, then when the water breaks, and then during the first attempts.
Indications for CTG during pregnancy
When can a doctor recommend doing a CTG during pregnancy? This study is carried out as part of monitoring a normally developing pregnancy in the third trimester. In addition, cardiotography is used to monitor the condition of the fetus in the following conditions:
- multiple pregnancy;
- oligohydramnios;
- increased risk of developing fetal hypoxia;
- high probability of complications in late pregnancy (hypertension, gestosis);
- anemia;
You will also need to do a CTG of the fetus in the intrapartum period (during childbirth).
The absence of timely CTG results in a delayed diagnosis of fetal hypoxia. This is the only method of prenatal assessment of the fetus.
Cardiotocography assessment
If fetal cardiotocography was performed, interpretation requires subjectivity and accuracy. It is for this purpose that a system for assessing this diagnostic was developed, which provides for assigning points to each of the indicators.
So, the assessment is considered correct if it is carried out according to 5 main parameters, each of which, in turn, is also assessed with specific points from 0 to 2. For example, the norm is if in total all points are about 8-10. Anything above 10 points is also considered normal. But if the score corresponds to 6-7, then this condition is diagnosed as pre-pathological and the attending physician may refer for additional studies, prescribe therapy and after it, prescribe a repeat CTG. But everything below 6 indicates that a pathological process is clearly present, namely, an intrauterine lack of fetal oxygen (or hypoxia). This condition requires both hospitalization and measures for a speedy delivery.
What is CTG?
CTG belongs to the group of fairly simple and safe methods for diagnosing the condition of the fetus while in the womb. With this test, carried out during pregnancy, the doctor studies the baby's heart rate during activity and peaceful pastime. Another equally important indicator is also measured - contractions of the uterus itself.
The check is carried out thanks to special sensors, which “receive” and record the relevant data in the form of 2 lines representing a graph. The first line (tachogram) reflects the characteristics of the child’s cardiac activity, and the second (histogram) reflects the change in the strength of the mother’s uterine contractions.
Among the pathologies that CTG can reveal are:
- the possible impact of the mother's illness on the child;
- fetal hypoxia (insufficient amount of nutrients);
- abnormal heartbeat in the baby.
It must be remembered that this diagnostic method does not serve as the only indicator of the child’s health, since changes could arise due to a response to unusual external influences or the use of prescribed drugs. In some cases, the mother's mood has a significant influence on the baby.
If a specialist suspects that the unborn child has any pathologies, more significant types of research are additionally prescribed, for example, Dopplerography or ultrasound.
If the indicators border on normal or pathological
When, at the end of a CTG, the result does not correspond to the norm, you should:
- do additional research, for example, such as a biophysical profile, ultrasound, determination of blood flow speed, etc.;
- exclude the fact of taking certain medications that affect the fetal heart rhythm;
- perform CTG again;
- resort to cardiotocography with additional measures (functional tests such as an exercise test, a stress/non-stress test, Stange/Genchi tests, as well as a mammary test).
