Fetal CTG is the norm
Absolutely every woman during pregnancy experiences how her child develops, whether everything is in order. Today, there are methods that allow a fairly reliable assessment of the fetus. One such method is cardiotocography (CTG), which reveals the relationship between fetal perturbations and heart rate. From this article you will find out what KTG is, what characteristics it evaluates, what indicators for the CTG of the fetus are the norm, and what influences the results of the study.
What is KTG?
Cardiotocography is based on recording the heart rate of the fetus and its changes depending on the effect of external stimuli or fetal activity.
Diagnosis is carried out with the help of two ultrasound sensors, one of which is strengthened on the abdomen of a pregnant woman, having previously determined the area of good hearing of the child's heartbeat.It is intended for recording the cardiac activity of the fetus. The sensor senses the ultrasound signal reflected from the child's heart, which is then converted by the electronic system into an instantaneous heart rate. The second sensor is attached to the abdomen in the region of the uterine fundus. He registers contractions of the uterus. To improve the passage of ultrasonic waves, the sensors are treated with a special gel. Also modern instruments are equipped with a remote control, by pressing a button which a pregnant woman can mark the movements of the fetus.
The results are displayed by the instrument on a paper tape in the form of a graph. The uterine contractions and fetal movements are also displayed there. According to the received data it is possible to judge, first of all, about the state of the nervous system of the baby, about his protective-adaptive reactions. If the CTG indicators of the fetus - the norm, it means that the baby feels comfortable, and its development is according to the terms.
What is required for CTG
Examination of a pregnant woman in an obstetrician-gynecologist's office includes listening to the child's heartbeat with a stethoscope. Deviation from the norm of heart rate (HR) in greater or lesser side indicates that the child is experiencing discomfort. In this case, the doctor sends the future mother to a more thorough study of the cardiovascular system of the fetus - CTG.
There is a clear relationship between the state of health of the pregnant woman and the state of the fetus. So, if the pregnancy was calm, without intrauterine infection, the threat of interruption, gestosis, the results of CTG are likely to be normal. If, with a good state of health of the pregnant woman, suspicious results of CTG are observed, it is necessary to re-conduct the examination in a week.
If a pregnant woman has serious health changes, it is necessary to carry out CTG as often as possible in order to prevent the occurrence of pathologies in the development of the fetus in time and take the necessary measures.
Features of the study
Assign CTG usually after 32 weeks of pregnancy, since only by this time the maturation of neuromuscular impulses occurs, and the method becomes the most informative.
For example, for the CTG of the fetus, the norm is 33 weeks - the presence on the chart of more than two accelerations. By this time they are caused by the response of the nervous system to fetal movements or to external factors. At earlier times, the accelerations may be related to the conditions of intrauterine fetal existence, so research can lead to false results.
Also by this time the fetus has a cycle of activity and rest, which is of great importance for this study. When CTG is performed during the fetal rest period, the results will always be positive, even if in fact there is a high degree of hypoxia. That's why the research should be conducted for at least 40 minutes. During this time, the fetus will necessarily increase motor activity, which will allow you to register changes in heart rate during its movement.
It is very important that a woman feels calm and comfortable during the study. An uncomfortable position or vivid emotions can cause a more active fetal movement, which will lead to false results. Usually during the procedure the woman sits in a comfortable chair or lies on the couch on her side.
In order to understand how to decipher the CTG of the fetus, we will analyze in detail, by what parameters it is evaluated.
Basal heart rate
Basal heart rate is the average heart rate of the fetus, calculated in 10-20 minutes. Determine it in the absence of fetal movement between contractions of the uterus without external stimuli, without taking into account the accelerations and decelerations.When carrying out CTG, the norm of the fetus is 110-160 beats per minute. Tachycardia, that is, the excess of the norm of the basal heart rate, can be observed with fetal hypoxia, anemia, developmental malformations and fetal heart failure, as well as with the feverish condition of the pregnant woman, the presence of intrauterine infection, and the function of the thyroid gland. Taking medications that have a cardio-stimulating effect can lead to an increase in fetal heart rate.
Lowering the basal level below the norm (bradycardia) may be due to hypoxia, heart defects of the fetus, as well as reduced arterial pressure of the mother, hypoxemia, prolonged compression of the umbilical cord, and the presence of a pregnant woman with cytomegalovirus infection.
Heart Rate Variability
This parameter is characterized by the presence of instantaneous oscillations - abnormalities of the heart rate from the basal level. In the analysis of CTG, the amplitude of instantaneous oscillations is usually studied, in the nature of which low oscillations are produced (deviation is less than three beats / min), medium oscillations (3-6 beats / min), high (amplitude more than 6 beats / min).
For the CTG of the fetus, the norm of 36 weeks is high oscillations, which testify to the well-being of the fetus. The presence of low oscillations indicates pathologies in its development.
Particular attention in the analysis of cardiotocograms is given to slow oscillations. Depending on their amplitude, a monotonic type is distinguished, for which a low oscillation amplitude (from 0 to 5 beats per minute), a transient type with an amplitude of 6 to 10 beats / min, wave-like (from 11 to 25 bpm) and a jumping type (amplitude above 25 bpm). An increase in the amplitude of the oscillations can be associated with moderate fetal hypoxia, as well as with the influence of external stimuli stimulating its nervous system. The decrease in the amplitude of oscillations can be caused by severe hypoxia, which leads to suppression of the function of the fetal nervous system, the use of narcotic drugs, tranquilizers.
Acceleration is a temporary increase in heart rate by at least 15 beats / min in comparison with the basal level and a duration of more than 15 seconds. On the cardiotocogram they look like high denticles. Accelerations are a response to external stimuli, contractions of the uterus, to the movements of the child. Their presence on the CTG of the fetus is the norm.
Deceleration is the reduction of the fetal heart rate by at least 15 beats / min for more than 15 seconds. The chart shows how significant cavities are. Distinguish early, late and variable decelerations. In addition, they are classified by amplitude as light with a decrease in heart rate to 30 beats / min, moderate - 30 - 45 beats / min, and heavy - from 45 beats / min. Decrease in heart rate may occur as a result of impaired placental blood flow, myocardial hypoxia, and compression of the umbilical cord.
CTG of the fetus. Norm of indicators
To assess the condition of the fetus, the World Health Organization has developed recommendations that specify the minimum and maximum allowable values for each of the parameters. According to these recommendations, CTG of the fetus (the norm for 33 weeks) should have the following values:
- Basal level of palpitation: 110-160 beats / min.
- Variability of the heart rate in the range of 5-25 beats / min.
- Two or more accelerations within 10 minutes.
- Absence of deep decelerations.
It is worth noting that for the CTG of the fetus the norm is 35 weeks or more the same as in 33 weeks.
Assessment of the fetus status by points
Decipher the results of CTG on a 10-point system, evaluating each criterion from 0 to 2 points. For the CTG of the fetus, the norm of 36 weeks, as well as during the entire third trimester, is 9-10 points, if the total score is from 6 to 8, this indicates oxygen starvation (hypoxia) without emergency threats, it is necessary to repeat the CTG procedure in a week;if 5 points or less - it means that the child experiences the strongest oxygen starvation, which can lead to serious neurological problems, emergency measures must be taken.
It should be remembered that even if the CTG of the fetus is 8 points or slightly lower, you do not need to be scared before the time. In this type of study, as well as in many others, there are factors influencing the informativeness of the testimony. The results strongly depend, for example, on whether the child is sleeping or awake. Experienced doctors when decoding cardiotocograms take into account factors such as weather conditions, the mood of a pregnant woman, the level of glucose in a woman's blood. If CTG data do not correspond to the norm, the doctor will prescribe an additional examination. Usually cardiotocography is performed twice in the third trimester of pregnancy, but in some cases even more, for example, in multiple pregnancy, high blood pressure, infections, diabetes, unsatisfactory results of ultrasound, bleeding, premature labor.
Possible errors in the interpretation of CTG data
- The child in the womb is in constant motion. Sometimes he can press the head of the umbilical cord, because of which the blood flow in the vessels of the umbilical cord is broken for a short time, which is reflected in the results of CTG. In this case, the cardiotocogram will be pathological in the case of a good fetal condition.
- Sometimes during oxygen starvation, the fetus includes protective reactions: there is a decrease in the oxygen consumption of tissues and an increase in resistance to hypoxia. In such cases, the child suffers, but this is not reflected in the CTG.
- With the development of pathology, the ability of tissues to perceive oxygen at a normal level in the blood can decrease, because of which the fetus does not react, and CTG will be normal, although it suffers from a lack of oxygen.
Considering all the above, it is necessary to understand that CTG of the fetus during pregnancy is a very important method of diagnosis, but to obtain a complete picture of what is happening, CTG data need to be compared with the data of other studies. To date, widely used ultrasound diagnosis and Doppler.
Where can I make CTG of the fetus
CTG is done free of charge in all women's consultations. You can conduct research in private medical centers, but already on a fee basis.
In maternity hospitals also carry out cardiotocography in the process of childbirth. This helps to assess the child's well-being in childbirth and contraction of the uterus, check the effectiveness of the treatment and the tactics of labor.
Some future mothers are afraid to conduct all kinds of research during pregnancy, believing that they can harm the health of the baby's future. Cardiotocography is absolutely safe, and it can be done as many times as necessary, without risk to health. In addition, it is painless, does not cause any unpleasant sensations.
We wish you an easy pregnancy and excellent health!