Attempts to create a device for recording fetal heart sounds - a kind of electrocardiogram for an unborn baby, led to the appearance of a cardiotocograph. Cardiotocography or CTG is the simultaneous recording of fetal heart rhythms and uterine contractions. I would like to note right away that at the moment fetal cardiotocography is the gold standard of the World Health Organization for assessing the condition of the fetus during pregnancy and the only objective criterion for such an assessment during childbirth.
The result of CTG recording - a cardiotocogram - is a graphic image in the form of two curves - fetal and uterine. The first is a record that reflects the change in heart rate every second. The second is similarly changing uterine activity. Scientists and practitioners around the world have created many evaluation tables and criteria for evaluating the received record. Below we will talk about how to make and decipher CTG.
You can listen to the fetal heartbeat from a fairly early pregnancy - about 12-16 weeks, but on the recommendation of the World Health Organization, the record carries relevant information starting from the 28-30th week of pregnancy.
Modern CTG recording devices are small devices that can be easily carried and moved. The device is equipped with two sensors - uterine and fetal, as well as special elastic belts for fixing them on the belly of a pregnant woman. Both sensors are lubricated with a special gel before use to improve conductivity.
The uterine sensor is installed on the bottom of the uterus, and the second midwife leads along the belly of the expectant mother, trying to find the best point for listening to the fetal heartbeat. Most of the devices have a second fetal sensor to simultaneously record the heartbeat of twins. After finding the heartbeat point, the fetal sensor is fixed with a belt, and the patient assumes a comfortable position. You can record the fetal heartbeat while sitting, lying down or even standing. Also, a woman is offered a special button, which she must press with each movement of the fetus.
Recording time is very variable. The minimum recording time is 10 minutes, but can be up to an hour. The fact is that the intrauterine life of a child implies an alternation of periods of rest with periods of wakefulness. If the baby is sleeping at the time of recording, then the graph turns out to be uninformative - the so-called monotonous type of CTG. Such a record cannot be used to assess the condition of the fetus, so such a cardiotocogram must be rewritten after a while.
By the way, there is a little secret to "wake up" the baby and get a good record. 10-20 minutes before the procedure, the expectant mother needs to eat some sweets, take a quick walk in the fresh air or drink an oxygen cocktail.
Of course, only a doctor is engaged in evaluating and decoding cardiotocograms. Self-assessment of the records is completely unacceptable, since in especially difficult cases even experienced doctors doubt the diagnosis for a long time.
As we have already mentioned, there are many evaluation criteria for deciphering CTG. I would like to note that domestic scientists are also involved in the creation of such criteria - Savelyeva, Voskresensky, Gerasimovich and others. At the moment, two rating scales are widely used - Dose-Redman and Fisher. Despite the variety of scales and tables, they all mainly use several basic cardiotocogram indicators:
The Dawes-Redman criteria are embedded in most CTG devices with the ability to automatically analyze cardiotocograms, that is, at the end of the recording, the cardiotocograph displays a column of numbers:
It is STV that is the criterion for assessing the condition of the fetus. It is important to understand that scale Dose-Redman is relevant only for the evaluation of a pregnant woman, but not relevant in the period of childbirth. Here is a gradation of variability values:
Automatic assessment of cardiotocograms necessarily takes into account the duration of pregnancy. That is why the decoding of the CTG of the fetus at 36 weeks of pregnancy will be slightly different from that at 28 weeks.
The Fisher scale is used for the so-called manual assessment of cardiotocograms. This scale is used in childbirth. There is a special table for evaluating each of the indicators in points: basal rhythm, the presence of accelerations and decelerations, the amplitude and frequency of oscillations. The sum of points received is evaluated as a result:
As we have already found out, cardiotocography evaluates the heart rate of an unborn baby, his motor activity and uterine contractility. Based on this, we list the conditions that can be tracked and suspected using CTG.
We emphasize once again that the obstetrician-gynecologist should deal with the decoding of CTG. It is the doctor who, having evaluated all the indicators of the cardiotocogram, decides whether its result is satisfactory. Further actions of the doctor will depend on how bad the result is:
It is very important in case of certain issues with CTG to carefully follow the doctor's recommendations, since this method is very informative and really accurately predicts the well-being of the fetus.
A woman meets many studies for the first time, some diagnostic procedures are not familiar to her, therefore, the expectant mother is alarmed, they make her doubt that everything is in order with her and the baby. One gynecologist said that for the first time a young woman came to the CTG procedure all in tears, with the full conviction that once an examination was scheduled, then a pathology was suspected ... a specific purpose. So what is this procedure - ktg? Why is she appointed? Let's look into these issues in detail.
Cardiotocography (CTG) is a research method that is based on the analysis of the variability of the fetal heart rate (in medical terminology, the fetus is the unborn baby from the eighth week of intrauterine development until the moment of birth). With fetal CTG, the frequency of the baby's movements and the contractile activity of the uterus are also recorded. CTG is carried out using Doppler-based cardiac monitors, which record changes in the intervals between individual cycles of the fetal cardiac activity.
Analyzing the results of CTG, one can assess the functional state, frequency of fetal movements, understand whether he is comfortable, whether there is enough oxygen, the frequency and strength of uterine contractions. Thanks to the fetal CTG procedure, the doctor can timely notice deviations in the course of pregnancy and provide the necessary assistance to the pregnant woman and the unborn baby in time. Fetal CTG is prescribed both for prophylactic purposes from 30-32 weeks of pregnancy to all women, and for medical reasons (in this case, the terms may be different).
Usually, if the pregnancy is going well, a woman undergoes a CT scan of the fetus in the 3rd trimester at least twice, if there are indications (aggravated obstetric history, entanglement of the umbilical cord, scars on the uterus, placental insufficiency, polyhydramnios or oligohydramnios, features of the development of the fetal cardiovascular system) - more often according to doctor's instructions. With planned hospitalization a few weeks before childbirth, women undergo daily fetal CTG, this procedure becomes familiar to them, and most are looking forward to it, because it shows the heartbeat of their crumbs, some devices reproduce the sound of the baby's beating heart.
Fetal CTG is completely painless for both the expectant mother and her future baby. A woman occupies a comfortable position half-sitting or reclining on her back or on her side; lying down is not recommended for the procedure, because. in the supine position, compression of the inferior vena cava may occur and the recording results will be distorted. Two sensors connected to the monitor are attached to the belly of the pregnant woman. One sensor captures the fetal heartbeat, and the second - uterine contractions.
Older heart monitors have another fetal movement sensor with a button that is placed in the woman's hands and she has to press the button every time she feels her baby move. New modern devices do not have such a device. The procedure lasts 30-35 minutes, so before it is carried out, the woman is recommended to get enough sleep, go to the toilet. If the child during the CTG is not active and sleeps in the mother's stomach, the procedure will not be informative.
To increase the activity of the fetus, a woman in the absence of allergies is recommended to eat one or two slices of chocolate. It is not recommended for a woman to worry, get upset, worry, these factors can contribute to the distortion of the results. The fetal CTG procedure is completely harmless, painless, has no contraindications and side effects from both the mother and the fetus. Also, fetal CTG can be carried out directly in childbirth in order to understand how the baby feels.
Deciphering the CTG of the fetus is the prerogative of gynecologists, but every woman can have an idea of \u200b\u200bwhat the results of the CTG mean, what the indicators are and whether they are the norm of the CTG. As a rule, by the 32nd week, the child’s cardiac reflex has already been formed, and for every movement he has a reaction of the cardiovascular system in the form of an increase in heart rate. Sensors record these indicators, which are recorded as a curve on a tape - a cardiotocogram. The gynecologist evaluates the curve in points from 1 to 10. According to this assessment, it can be concluded how the child feels in utero, how much his body, including the cardiovascular system, is provided with oxygen, whether there is fetal hypoxia.
It is difficult for an unprepared person to say what a cardiotocogram means. It shows a continuous line and teeth, directed mainly upwards, less often downwards. But how to decipher these indicators? On the cardiotocogram of the fetus, the doctor evaluates the following indicators:
For each of the four indicators, the doctor assigns points, from 0 to 2. And then, summing up the result, he receives the final number of points, which gives an assessment of the condition of the fetus and its cardiac activity.
Fisher's rating scale is as follows:
Normal CTG indicators are a concept that fits into very specific criteria, namely: the basal rhythm should be 119-160 beats per minute, the deviation amplitude is 7-25 beats per minute, at least 2 accelerations in 10 minutes, the absence decelerations or mild decreases in heart rate. These are normal indicators. But you should always remember that one record does not make a diagnosis, and small deviations from the norm are not a pathology. The graph data may vary depending on whether the baby is sleeping or awake, is in a calm or active state, and also on which week of pregnancy the examination is performed.
The doctor should be alerted to the results of CTG, which have significant deviations from the normal range: if the basal rhythm is less than 110 or more than 190 beats per minute. A low frequency of 110 or less indicates a slowing of the heartbeat in the fetus, and a high one, on the contrary, indicates a pronounced increase. Both can indicate fetal hypoxia, oxygen starvation. A basal rhythm over 190 and under 110 is scored as 0 points. It is also not very good when there are no accelerations in response to the movement of the fetus. This may indicate tension and exhaustion of the fetal compensatory reactions, immaturity of the cardiac reflex.
Deep and frequent decelerations always alert the doctor, they may indicate a violation of placental blood flow and require careful study. A monotonically variable basal rhythm or an amplitude of less than 10 or more than 25 beats also raises questions for the doctor. If the decoding of fetal CTG gives a dubious result of 6-7 points, it is necessary to repeat the study and supplement it with other examination methods to determine the reasons that led to this result. But do not immediately panic, it can only harm the condition of the unborn baby.
The reason for the immediate hospitalization of a pregnant woman is threatening indicators on the Fisher scale 1 point - 5 points.
You are pregnant, you feel how your baby is growing, kicking, and your meeting with him will take place very soon, but the doctor has not yet prescribed CTG for you? Why? Perhaps your pregnancy is going well, and its term has not come to 32 weeks, you have no indications for an earlier pregnancy. This is just a reason for joy, and in no way a reason for concern.
No. If any deviations as a result of the procedure were identified, the doctor will refer you to other examinations (laboratory, instrumental). And already in a comprehensive assessment, taking into account the data of all studies, a diagnosis will be made, the results of deciphering the CTG of the fetus will be confirmed or refuted.
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Under normal conditions for KTG ( cardiotocography)
a number of parameters are recorded that must be taken into account when evaluating the results of the study. When CTG is evaluated:
In the study of CTG, there are:
Instantaneous oscillations can be:
Slow oscillations
As for slow oscillations, they are characterized as changes in the fetal heart rate within one minute. On CTG, they appear as small waves with sharp teeth.
Depending on the nature of slow oscillations, CTG can be:
Also, when assessing slow oscillations, their number is taken into account, that is, how many times the heart rate increased or decreased ( ) in a minute.
On KTG can be registered:
Fetal movements are determined on the lower line of the cardiotocogram, which registers uterine contractions. The fact is that uterine contraction is recorded by a sensor that measures the circumference of a woman's abdomen. When the uterus contracts, the circumference of her abdomen changes somewhat, which is determined by a special sensor. At the same time, when moving ( movement) of the fetus in the uterus, the circumference of the abdomen may also change, which will also be recorded by the sensor.
Unlike uterine contractions ( which on the lower line of the cardiotocogram look like smoothly increasing and also smoothly decreasing waves), fetal movements are determined in the form of sharp rises or jumps. This is due to the fact that when the uterus contracts, its muscle fibers begin to contract relatively slowly, while the movements of the fetus are characterized by relative speed and sharpness.
The reason for the absence or mild fetal movements may be:
Measurement of the tone and contractile activity of the uterus is called tocography. Tokography can be external ( is part of the CTG and is carried out using a strain gauge installed on the surface of the mother's abdomen) and internal ( To do this, a special sensor must be inserted into the uterine cavity.). It is possible to accurately measure the tone of the uterus only with the help of internal tocography. However, perform it during pregnancy or childbirth ( i.e. before the baby is born) impossible. That is why, when analyzing CTG, the tone of the uterus is automatically set to 8 - 10 millimeters of mercury. In the future, when registering the contractile activity of the uterus, indicators that exceed this level are evaluated.
During the training bout, there is also a slight contraction of the uterus and an increase in its size in the bottom area, which is captured by a sensitive strain gauge. At the same time, the same changes will be noted on CTG as in normal contractions, but less pronounced ( that is, the height and duration of the curvature of the bottom line will be smaller). In terms of duration, the training bout takes no more than a minute, which can also be determined on the graph.
Sinusoidal rhythm is characterized by:
Normally, STV should be more than 3 milliseconds ( ms). With a decrease in this indicator to 2.6 ms, the risk of intrauterine damage and fetal death increases to 4%, and with a decrease in STV less than 2.6 ms, up to 25%.
Many different scales have been proposed, but the most common today is the Fisher scale, which is considered the most reliable and accurate.
The assessment of CTG on the Fisher scale includes:
Fisher's scale in the Krebs modification when assessing CTG
Estimated parameter | Number of points |
||
1 point | 2 points | 3 points |
|
Basal Rhythm | Less than 100 beats per minute. | 100 - 120 beats per minute. | 121 - 159 beats per minute. |
Over 100 beats per minute. | 160 - 180 beats per minute. |
||
Amplitude of slow oscillations | Less than 3 beats per minute. | 3 to 5 beats per minute. | 6 to 25 beats per minute. |
Number of slow oscillations | |||
Number of accelerations | There are no accelerations. | 1 to 4 sporadic ( random) accelerations in 30 minutes. | More than 5 sporadic accelerations in 30 minutes. |
Decelerations | late or variable. | late or variable. | Missing or early. |
Number of fetal movements | None. | 1 - 2 movements in 30 minutes. | More than 3 movements in 30 minutes. |
Evaluation of CTG according to the FIGO method
Criterion | Interpretation of results |
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Norm | Prepathology ( "suspicious" CTG) | Pathology |
|
Basal Rhythm | 110 - 150 beats per minute. | 100 - 109 beats per minute. | Less than 100 or more than 170 beats per minute. |
151 - 170 beats per minute. |
|||
Rhythm variability | 5 - 25 beats per minute. | 5 - 10 beats per minute for 40 minutes. | Less than 5 beats per minute. |
sinusoidal rhythm. |
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Number of accelerations | More than 2 within 40 minutes. | Missing for 40 minutes. | Absent at all. |
Decelerations | Absent or single variable. | Variable. | Variable or late. |
The Dawes-Redman criteria include:
If the monitor displays the inscription “criteria not met”, then one or more of the listed indicators does not correspond to the norm. In this case, the study should continue for a minimum of 40 minutes. If the inscription “criteria met” does not appear, there may be a violation of the condition of the fetus in the womb. At the same time, a more detailed examination of the woman is recommended, as well as the repetition of CTG in dynamics ( same day or next day).
PSP calculation during pregnancy can determine:
A non-stress test can be:
There are a number of pathological conditions that can be identified using the correct decoding of CTG. The sooner pathological changes are detected, the sooner the doctor will take measures to eliminate them, which can save the life of the child. The cause of fetal bradycardia can be:
With acute ( rapidly developing) hypoxia, it is extremely important to diagnose and eliminate it in time, since otherwise damage to the fetal nervous system and death of nerve cells of the central nervous system may occur ( central nervous system), which can cause developmental disorders or even intrauterine death of the fetus. That is why any doctor conducting CTG should be able to recognize the main signs of hypoxia.
The presence of fetal hypoxia may indicate:
On CTG, this can be manifested by alternating sharp rises in heart rate ( characteristic of the initial stage of hypoxia), which are immediately followed by sharp decreases in heart rate ( characteristic of more severe hypoxia). These changes are associated with fetal movements recorded on the tokogram. The detection of such changes is an indication for urgent delivery by caesarean section, since otherwise irreversible damage to the nervous system of the fetus and its death are possible.
Although CTG cannot be used to diagnose oligohydramnios, the study may reveal signs of initial or severe fetal damage ( in particular, an increase or decrease in heart rate, signs of hypoxia, and so on), which may serve as a reason for a more detailed examination of the woman. If, against the background of a “bad” CTG, oligohydramnios is detected, the issue of premature delivery should be raised. At the same time, it is worth noting that even with confirmed oligohydramnios, a woman can have an absolutely normal cardiotocogram.
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The condition of the fetus can be assessed by various methods. It is considered the most accessible and effective. Its advantage is a 100% guarantee that nothing threatens the fetus in the presence of signs of well-being. Questionable results indicate a lack of oxygen and serious pathologies.
In order for the period of bearing a child to end safely, it is necessary to control the condition of the fetus. This task is performed by doctors using various methods. The most common method is cardiotocography. The study is based on the analysis of the variability of the frequency of contractions at rest, during movement, in conditions of uterine contractions.
There are certain rules for conducting CTG. The position of the woman plays a very important role. The results of the study depend on the posture. Fetal cardiotocography can be performed in the position of the expectant mother lying on her side or half-sitting. Sometimes a woman is allowed to stand. The choice of position depends on the research technique, the desire of the patient and on which apparatus is used. Carrying out cardiotocography while lying on your back is undesirable, since the results obtained in such cases turn out to be false.
Another rule for cardiotocography concerns the gestational age. The first contractions of the fetal heart appear on. However, they are not controlled by the nervous system, so it is pointless to conduct a study at this time. CTG is prescribed for pregnant women much later.
In most cases, expectant mothers receive referrals for pregnancy testing. However, there are also devices that allow you to perform CTG from the 26th week. Indications for conducting a study in a antenatal clinic is the presence of the following risk factors for oxygen deficiency:
In a maternity hospital, indications for CTG of the fetus are delayed labor after rupture of the membranes, infections of the kidneys, bladder and genital tract, uterine rupture, childbirth complicated by a short umbilical cord, its prolapse or entanglement around the fetal neck. This list should also include placental abruption, antepartum hemorrhage with bleeding disorders, and primary (secondary) weakness of labor.
Carrying out the cardiotocography procedure
A special device is designed to perform cardiotocography. It is called a cardiotocograph. An ultrasonic sensor is used to capture and record the fetal heartbeat. It is attached to the belly of the expectant mother in the place where the audibility of the fetal heart sounds is the best.
The device, when performing CTG, still registers uterine contractions. This is done using a strain gauge. It is fixed in the fundus of the uterus. Changes in heart rate and uterine contractions are displayed on the heart monitor.
The information that the device converts is also recorded on paper in the form of an image. According to the chart at the top, experts evaluate. At the bottom of the tape, uterine contractions and fetal movements are displayed.
Not every woman has a happy gestation period. Sometimes intrauterine fetal death occurs (before or after childbirth). Statistics show that in 60% of cases death occurs due to hypoxia. The remaining 40% account for other causes (malformations, chromosomal abnormalities, intrauterine infections).
Fetal hypoxia is a set of changes in the body of the fetus caused by insufficient oxygen supply to its organs and tissues. The consequence of oxygen deficiency is asphyxia. With it, the fetus suffers from a lack of oxygen and an excess of carbon dioxide. Due to oxygen starvation, irreversible changes occur in the developing organism, it is affected.
Children who have experienced an acute lack of oxygen are born with multiple organ disorders. Babies are observed:
In some cases, the result of asphyxia is cerebral palsy.
To detect hypoxia in the fetus, doctors perform cardiotocography. By assessing the work of the heart. If changes in the functioning of the organ are not observed, then the fetus does not experience oxygen starvation. But pathological rhythms may indicate hypoxia, but not in all cases. Sometimes a violation of cardiac activity is associated with malformations. In order to make an accurate diagnosis, expectant mothers are assigned additional studies in addition to cardiotocography.
Specialists, deciphering the cardiotocogram, determine the basal rhythm, evaluate the frequency and amplitude of oscillations, detect decelerations and accelerations, and determine episodes of high and low variability. These indicators are very important. From them you can find out if the fetus suffers from a lack of oxygen.
Results of cardiotocography
The basal rhythm is the average fetal heart rate. The norm of this indicator at the 30-37th week of pregnancy is from 120 to 160 beats per minute. A condition in which the basal rhythm is 160 beats per minute or more for more than 10 minutes is called tachycardia. The reasons for its occurrence may be as follows:
There may be such a situation when more than 10 minutes the basal rhythm is less than 120 beats per minute. This condition is called bradycardia. Most often it occurs due to:
An equally important indicator of the cardiotocogram is the frequency of oscillations. This term refers to the number of oscillations of the same type of basal frequency that occur in 1 minute. The rate of this indicator is from 3 to 6 beats per minute. Together with the frequency, the amplitude of oscillations is determined - the difference between the absolute minimum and maximum of all oscillations over a 10-minute period, excluding decelerations and accelerations. The normal values of this indicator are 10-30 beats per minute.
Decelerations - decrease in heart rate lasting from 15 seconds to 10 minutes with an amplitude of more than 15 beats per minute. They may occur due to the impact of adverse factors on the central structures of the fetus or irritation of baroreceptors.
Acceleration - an increase in the frequency of contractions of the fetal heart. They last more than 15 seconds and exceed the basal rate by 15 beats per minute. Accelerations are sporadic and periodic. The first appear in response to fetal movements or the action of external stimuli. Periodic accelerations occur due to uterine contractions.
The state of the fetus is assessed according to the point system proposed by Fisher. Each indicator is assigned a score of 0 if:
Indicators are estimated at 1 point if:
If the values are within the normal range, then each indicator is assigned 2 points.
Summing up all the points, a number is obtained by which the condition of the fetus is determined.
If the final result of CTG is equal, then this means that the fetus does not experience oxygen deficiency. With 5-7 points, the condition of the fetus is considered doubtful, and with 0-5 - unsatisfactory.
LTV is one of the indicators characterizing the fetal heart rate variability. It is the average value of all minutely sums of the maximum deviations of the fetal heart rate from the basal level. The LTV norm is 30−50 ms.
High and low episodes are measures of basal rate variability. High episodes are those parts of the heartbeat recording in which at least 5 out of every 6 consecutive minutes have an LTV above, and low episodes below a specific level. The level itself has no absolute value.
If there are high episodes in the results of fetal CTG, then this is considered a good indicator. Their presence indicates that the condition of the fetus is satisfactory.
When the examination is scheduled before the 32nd week of pregnancy, the CTG values are not within the normal range. This is especially true for heart rate. At 32-37 weeks of pregnancy, it is 120-160 beats per minute. Until the 32nd week of pregnancy, the indicator can fluctuate between 140-160 beats per minute. A decrease in heart rate indicates that the fetus is deficient in vital elements.
In conclusion, it is worth noting that obstetrician-gynecologists are obliged to preserve the health of the expectant mother and ensure the possibility of giving birth to a healthy child. This goal is achieved thanks to cardiotocography - a method that allows you to assess the condition of the fetus.
There are several ways to evaluate cardiotocograms. One of them is the method of mathematical analysis. It was proposed in the early 80s by Professor V. N. Demidov. First, it was necessary to carry out the analysis with manual processing of the monitor curve. Then it was planned to automate this process.
A few years later, Professor V. N. Demidov developed an apparatus - a computerized antenatal heart monitor. The features of the device are that it determines the duration of the study and, if necessary, extends it, eliminates the effect of sleep on the result and takes into account fetal movements.
The assessment is carried out according to the PSP. This abbreviation indicates the condition of the fetus. By its value, you can determine whether there are violations in the fetus, whether it is healthy.
PSP values calculated during CTG during pregnancy can range from 0 to 4.0. If the indicator is less than 1.0, then this confirms that the fetus is healthy. Values from 1.1 to 4.0 are due to any pathologies:
During delivery, when performing automated cardiotocography, the indicator is calculated using a 10-point system. It is similar to the Apgar scale, which is a system for quickly assessing a child's condition. Testing is carried out at 1-5 minutes after birth. The following criteria are evaluated (each of them is assigned from 0 to 2 points):
If the child has 7-10 points on the scale, then this means that his condition is good. If the final result is equal to 5-6 points, then specialists are closely watching the baby. After 5 minutes, they re-test. The result, which has risen to 7-10 points, indicates that there is no need to worry about the child's condition. If the scores are at the same level, then the baby continues to be closely monitored.
In the prenatal state, it is rather problematic to find out how the fetus feels. Ultrasonic methods come to the rescue, but recently there have been scientific publications about the dangers of frequent use of this method. And this method requires special training of an obstetrician-gynecologist.
To assess the condition of the fetus in the mother's tummy, cardiotocography (CTG) is used. Thanks to this method, the doctor can record the fetal heartbeat and understand how the unborn baby feels in the womb. CTG during pregnancy can be recorded even by a midwife trained in the method of fixing the heartbeat.
Pregnant women can record the heartbeat any number of times a day. This method of registration of the fetal heart has no contraindications.
Sometimes it becomes necessary to register the condition of the unborn child throughout the day. In such cases, the mother should not be afraid either for her health or for the well-being of her baby, the method is absolutely safe.
Cardiotocography records the fetal heartbeat. A change in frequency indicates various pathological processes that can lead to a disease in the unborn child. Fetal CTG is used for the following diseases or suspicions of them:
CTG is used during childbirth and it is recommended to conduct the entire birth period under the control of monitors. Especially if during pregnancy there was a risk of developing placental insufficiency, late preeclampsia or other pathology leading to fetal hypoxia.
To record the baby's heart, there are many modifications of the apparatus. Some simply record the heartbeat curve on paper, others, in addition to recording, produce a result and an assessment of the heartbeat.
In addition to the heartbeat, the CTG machine can be equipped with a uterine muscle contraction sensor to record contractions. Sometimes a button can be attached to the monitor to record the movement of the fetus, and the woman records them when recording CTG. The contractions and movements of the fetus, marked on the tape next to the heartbeat, are necessary for a correct assessment and interpretation. For better sound conductivity, the sensors are lubricated with a special gel.
Cardiotocography should be recorded no earlier than 32 weeks. Only during this period is a full-fledged connection between the mother and the fetus formed. Until this time, you can record the baby's heartbeat, but the transcript of the record will be unreliable.
It is very important to use this method at a time when the fetus is awake and there are at least minor signs of activity. During the child's sleep, the recording will be monotonous, which is a variant of the pathology.
It is necessary to register the heartbeat within 30-40 minutes. But if the child did not make active movements or moved very violently, and you did not receive continuous recording, extend the recording to 60 minutes.
The decoding of the received data can be done in different ways. It depends on the type of monitor on which the CTG was recorded or on the period in which the fixation was made. Transcription during childbirth is different from that during pregnancy.
The first metric to look at is heart rate . In the fetus, it fluctuates and changes very quickly, so they take the average value. This average is called the basal rhythm. The norm of fetal CTG implies a heartbeat of 120-160 beats / minute. Both an increase and a decrease in the pulse indicate a pathological condition of the child.
The baby's pulse changes every second. Here it is 120, and now 125 and changed again - 121 beats / min. These changes form a small "fence" on paper - oscillations. How many units the rhythm changes every instant is called oscillation amplitude . How often does the fetal heart rate change? oscillation frequency . The final assessment and interpretation of the CTG of the fetus also depends on these two parameters.
There are two more parameters in the entry. Acceleration - this is a sharp increase in the child's pulse for 0.5-1 minute. On the record, it will be displayed as a “mountain”. As a rule, the presence of accelerations, especially in response to fetal movement, is a good sign. Deceleration - a sharp decrease in the fetal heart rate. The presence of heart rate drops is a poor prognostic sign.
The doctor evaluates all these signs according to a point system and puts on each item from 0 to 2 points.
But the doctor may not give points. With experience, an obstetrician-gynecologist evaluates visually and distinguishes “good” CTG from “bad”.
If the device that records the heartbeat curve itself evaluates it, deciphering the fetal cardiotocography is not particularly difficult. All data will be printed at the end of the study, and the record is kept for as long as the machine needs to evaluate the data.
In this case, the main criterion is the variability, which normally should not be less than 4 or more than 20. But the doctor will also pay attention to all other columns of the results.
There are a lot of types of pathological rhythms in a baby and only a specialist can recognize them. One of these options is to reduce the basal rate to less than 120 beats per minute.
This rhythm may be associated with:
Tachycardia above 160 beats per minute can be caused by:
Fetal cardiotocography helps to suspect the diagnosis. This method is not definitive and requires the support of other studies.
Often, a preliminary diagnosis made on the basis of cardiotocography is not confirmed by other methods. This may be due to the temporary conditions of the unborn baby or some registration features:
In this regard, the woman is offered to repeat the recording after some time or confirm it with other instrumental methods.
Almost every pregnant woman who is registered in the antenatal clinic knows what is fetal CTG. Do not be upset in advance if this method showed any pathology.
Very often this is just a temporary state of the fetus, and the picture will change at the next registration. But still, if the diagnosis is confirmed, and will not respond to treatment for hours or days, the doctor will raise the issue of early delivery.
Recently, portable monitors have begun to appear to record the baby's heartbeat. Thanks to this, parents can listen to the heartbeat of their child around the clock.
How to prepare for fetal CTG?
Special preparation for this method is not required. A woman should come rested in a good mood and have a little snack. Excessive food intake or hunger can lead to pathological behavior of the unborn baby. It is advisable to choose a time when your baby is awake and moving.
When is fetal CTG done?
This method is used starting from the 32nd week of pregnancy. At every or almost every visit to the antenatal clinic, a CTG is recorded. In many hospitals, the fetal heart rate is recorded daily, and if there are deviations in the recording, even twice a day. At the appointment in the antenatal clinic, in the case when the doctor does not hear the beat well with the help of a tube, he can record a CTG.
