Cardiotocography (abbreviated CTG) makes it possible to assess the condition of the baby, its cardiac activity and the development of pregnancy in general.
According to the examination plan for pregnant women, cardiotocography is prescribed weekly starting from the 32nd week. The last diagnostic procedure can be performed in the maternity hospital.
What is fetal CTG, how and why is it performed?
Cardiotocography– a diagnostic procedure during which the baby’s heartbeat, motor activity and contractions of the uterine muscles are continuously recorded.
Purpose of the procedure– identification of signs of hypoxia, fetal anemia, abnormalities in the functioning of the heart (including congenital anomalies). CTG also helps diagnose oligohydramnios and fetoplacental insufficiency.
Modern CTG equipment is equipped with sensors to assess the condition of two babies at once. This is true if a woman is pregnant with twins.
The first planned cardiotocography is prescribed at 32 weeks, since by this time the fetus’s cardio-contractile reflex is already quite well formed. Only from this period is the relationship between the child’s activity and his heart rate clearly visible.
Cardiotocography can be prescribed at earlier stages; pathological rhythms are clearly recognized from the 20th week of pregnancy.
CTG procedure: how is it performed?
Cardiotocography is carried out using special equipment, which includes two sensors connected to a device for recording data. The first sensor records the baby's heartbeat, and the second - the contractions of the uterine muscles.
So, first, the doctor places a stethoscope on the abdomen - a tube with a flared end, with the help of which the child’s heart is listened to during each visit to the obstetrician-gynecologist.
This is how the best place to listen to the baby’s heartbeat is determined. Next, an ultrasonic sensor is placed on this area and secured around the body with a belt. This sensor will record the fetal heart activity.
The second sensor (strain gauge) is also fastened with a belt to the stomach, but in the area of the fundus of the uterus (above the navel, approximately under the ribs).
A gel is used to remove the air layer between the sensor and the skin of the abdomen, which interferes with data reception. It is absolutely safe for the baby and mother.
Also, the expectant mother is given a remote control, which is equipped with a button. The woman should press it every time she feels the baby moving. This will allow you to evaluate changes in the fetal heart rate during the period of its activity.
Cardiotocography most often lasts 40, 60 or 90 minutes. But some LCD procedures are carried out in 20-30 minutes, and in the maternity hospital, at the onset of labor, CTG takes about 10-15 minutes. This is enough to draw conclusions about the condition of the fetus based on the obtained cardiogram.
Preparing for CTG
No preparation is required for cardiotocography. But in order for the indicators to be objective, during the procedure the woman must take the most comfortable position.
Usually, the expectant mother is asked to sit, leaning back on the back of a chair or lie half-sided (i.e., you need to lie on your back and slightly turn on your left side, and place a bolster or pillow under your right).
Cardiotocography should not be performed “lying on your back”!
This way the inferior vena cava will not be compressed, as a result of which conclusions about the condition of the fetus will be as reliable as possible.
There is no guarantee that the child will be awake during the CTG. Therefore, it is recommended that a woman eat a piece of chocolate 10-15 minutes before the procedure (you can eat it during the procedure), so the baby will begin to be active.
Also, 8-12 hours before the procedure, you should not take No-shpa (antispasmodics), sedatives, painkillers and other drugs that may affect the result of cardiotocography.
And on top of everything else, the woman must be healthy at the time of the procedure, since acute respiratory infections/ARVI and other infectious and inflammatory diseases can cause fetal hypoxia. In this case, the CTG will need to be retaken after recovery.
With low hemoglobin, the fetus may show signs of hypoxia!
Cost of CTG
In budgetary Russian institutions the procedure is free. In private clinics, the cost consists of several factors: the quality of equipment and service, and the level of the institution. In private clinics in Russia, the price range is about 800-1200 rubles for one cardiotocography procedure.
Is CTG dangerous for the fetus?
Cardiotocography has no contraindications. This procedure is 100% safe for both the baby and the mother. It is completely painless and even pleasant, since the woman has the opportunity to listen to her baby’s heartbeat for almost an hour.
Cardiotocography during pregnancy is prescribed once a week, but it can be done at least every day. This informative method allows you to timely determine whether something threatens the fetus. If indicators deviate from the norm, additional diagnostic methods are prescribed, as well as preventive and therapeutic measures.
Interpretation of CTG results + norm of all indicators
The result of CTG is curves printed on paper tape. After deciphering them, the doctor determines whether there are deviations from the norm.
Cardiotocography evaluates indicators such as:
- basal rhythm (basal heart rate)– the number of contractions of the baby’s heart per minute.
The device itself determines the fetal heart rate according to the read data. If there are disturbances in the functioning of the heart, the heart rate may be calculated incorrectly (halved or vice versa).
It is important to know!
If in a normal state the norm is a heart rate of 120-160 beats/min, then during physical activity, as well as with the pelvic position of the fetus, the normative heart rate is much higher - 180–190 beats/min.
During a post-term pregnancy, it is considered normal if the lower limit of the basal heart rate is in the range of 100-120 beats/min.
During the rest period, the baby’s heart rate (with cephalic presentation) should be in the range of 120-160 beats/min.
If the heart rate is more than 160 beats/min, then this indicates that the baby is developing tachycardia:
- moderate – with a basal heart rate from 160 to 180 beats/min;
- pronounced – with BHR over 180 beats/min.
Tachycardia can be observed with: mild fetal hypoxia, anemia in the child, inflammation and infection of the amnion (amnionitis), excessive production of thyroid hormones in the expectant mother (hyperthyroidism).
When heart rate is more than 200 beats/min. and the absence of basal rhythm variability, the child is diagnosed with supraventricular tachycardia, which can lead to the development of heart failure.
If the fetal heart rate is less than 120 beats/min., then this indicates bradycardia:
- moderate – with a basal heart rate of 100-120 beats/min;
- pronounced – with BHR less than 100 beats/min.
The cause of bradycardia may be moderate or significant fetal hypoxia, severe anemia, or the presence of congenital heart disease.
As a rule, when the heart rate is less than 100 beats/min. and virtually no rhythm variability, emergency delivery is performed. In this condition, the risk of intrauterine death of the child is very high.
A sinusoidal type of heart rhythm is also a pathological basal rhythm (see graph 1), when the cardiogram looks like a wavy line (without sharp teeth). This basal rhythm is due to the development of anemia in the fetus, the presence of severe hypoxia, or the course of an immunoconflict pregnancy.
Chart 1 – Sinusoidal basal rhythm
If the heart rate is sinusoidal and oxygen deficiency in the fetus is confirmed, the issue of emergency delivery is decided in order to save the baby’s life.
- heart rate variability characterized amplitude(the difference between the largest and smallest number of heart rates) and oscillation frequency(number of oscillations in 1 minute).
Heart rate range has no such diagnostic value. It can reach 50 and even 90 beats/min, which is quite acceptable.
Normally, the amplitude should be in the range from 6 to 25 beats per minute, and the frequency - from 7 to 12 times per minute.
An increase in the number of oscillation amplitudes (over 25 beats/min) is called in medicine “saltatory rhythm” (constantly jumping teeth, often with an increasing character, see graph 2).
Saltatory heart rhythm is observed with moderate fetal hypoxia, entanglement of the umbilical cord around the neck/torso or with compression of the umbilical cord (compression of the umbilical cord, for example, when it is located between the baby’s head and the mother’s pelvic bones).
Graph 2 - Saltatory fetal heart rate
Decrease in oscillation amplitude to less than 6 beats/min. called “monotonous rhythm” (see graph 3, it does not have sharp, high teeth).
A monotonous heart rhythm is observed with fetal hypoxia and acidosis, cardiac development defects, tachycardia, or if the fetus is only sleeping at the time of diagnosis. Also, if a pregnant woman took a sedative shortly before the procedure, then this may affect the decrease in the child’s heart rate variability.
Graph 3 - Monotonous fetal heart rate
The absence of rhythm variability (0-1 beats/min) is called a “silent rhythm” (see graph 4).
A silent rhythm occurs with severe hypoxia of the fetus, severe damage to its central nervous system, and malformations of the fetal heart incompatible with life.
Graph 4 – “Mute” or “zero” heart rate
- acceleration (increased heart rate). With external influence (palpation of the fetus during a vaginal examination), with contractions or movement of the baby himself, his cardio-contractile reflex is triggered, and his heartbeat quickens.
Normally, the heart rate should be accompanied by accelerations, with a frequency of 2 or more accelerations per 10 minutes. On the graph, accelerations are displayed in the form of tall teeth (they are marked with check marks in the example).
Graph 2 – Example of a normal fetal CTG
Let's calculate (using an example) how many accelerations there were during each 10 minutes: in the first 10 minutes there were 4 accelerations, in the second 10 minutes there were also 4 accelerations. Total 8 accelerations.
- deceleration (slowing heart rate)- these are the reactions of the child’s body to compression of his head during contraction of the uterus.
Normally, decelerations should be absent. It is permissible to have only fast (early) decelerations which occur during uterine contractions. Slight early decelerations are not an adverse event.
On the cardiogram, decelerations look like large depressions (in graph 2 they are indicated by crosses).
While some devices themselves mark accelerations, the devices do not mark decelerations.
Slow (late) decelerations, which occur within 30-60 seconds after the next uterine contraction, indicate fetal hypoxia and fetoplacental insufficiency, and long-term ones indicate premature placental abruption and other complications of pregnancy.
According to the maximum amplitude of slow decelerations, the following degrees of severity of hypoxia are distinguished:
- light – with an amplitude of no more than 30 beats/min.;
- moderate – with an amplitude from 30 to 45 beats/min.;
- heavy – with an amplitude of more than 45 beats/min.
Fetal movements. The baby’s physical activity is also recorded, which the pregnant woman reports to the computer using a button. 1 hour of research must be recorded at least 10 fetal movements.
The presence of hiccup-like movements with a normal cardiogram does not indicate oxygen starvation of the fetus.
Breathing movements. Their frequency must be more than 1 time and last at least 30 seconds.
Fetal condition indicator is a computer assessment of the baby’s condition, which is automatically provided by the device based on the results of cardiotocography.
The assessment of the fetal condition is calculated mathematically using the data obtained. The accuracy of such an assessment is 90%, while the accuracy of a visual assessment of the cardiogram results by a doctor is only 68%.
Here is a breakdown of the fetal condition indicators, which are within the following limits:
- 0-1.0 – healthy fetus;
- 1.1-2.0 – initial disturbances in the condition of the fetus;
- 2.1-3.0 – severe disturbances in the condition of the fetus;
- 3.1-4.0 – pronounced disturbances in the condition of the fetus.
Sleep adjustment is also calculated automatically and is necessary to obtain a more accurate final CTG result. By taking this indicator into account, the accuracy of diagnosing the fetal health status increases.
The line “correction for sleep” indicates the period of time when the fetus was sleeping, for example, 0 – 30 = 30. This means that from the beginning of the recording until the 30th minute, the fetal heartbeat was calm, the baby was sleeping at that time. And diagnostics must be carried out only during the baby’s waking hours.
The woman is asked to change her body position or eat some chocolate.
This is all the information regarding the first graph on the tape - the fetal cardiogram. The second graph is tocogram. It reflects the contractile activity of the uterus (or uterine SA), which should not exceed 15% of the baby’s heart rate, and should not last more than 30 seconds.
The final assessment of the fetal condition is given on a 10-point (according to Fischer) or 12-point (according to Krebs) scale.
- up to 4 points. The child suffers from severe hypoxia. Emergency delivery is required.
- 5-7 points. Non-life-threatening oxygen starvation of the fetus is observed. It is advisable to conduct additional studies of his condition or repeat CTG in a day or two.
- 8-10 points according to Fisher or 9-12 according to Krebs. Good fetal condition.
Deviations from the norm cannot be the basis for making a 100% diagnosis, since CTG provides information about the baby’s condition only during a certain period of time. To confirm or refute a particular ailment, repeated procedures of cardiotocography, Dopplerography and ultrasound are prescribed.
About poor CTG results he says:
- basal rate less than 100 or more than 190 beats per minute;
- rhythm variability less than 4 beats per minute;
- lack of accelerations;
- presence of slow decelerations.
If the results of cardiotocography are very poor, the doctor refers the pregnant woman to a cesarean section or induces labor artificially. During such a delivery, CTG can be performed more than once. In such a situation, this procedure allows you to determine whether there is a risk to the baby’s health.
It also happens that a child experiences oxygen starvation, but he has already adapted to this condition. Therefore, CTG will not show any deviations from the norms.
Normal fetal cardiotocogram. What is she like?
CTG is considered normal if:
- basal rate not lower than 120 (acceptable 110) and not higher than 160 beats/min.;
- high variability is indicated in minutes, there should not be low variability;
- number of accelerations - in every 10 minutes of the diagnostic procedure there must be at least 2 accelerations (provided that there are noticeable contractions in these 10 minutes);
- the number of rapid decelerations – their presence is acceptable, but ideally there should be none at all;
- number of slow decelerations – 0 (normally they should be absent);
- maximum amplitude of slow decelerations – 0 beats/min.;
- number of fetal movements – at least 5 per half hour;
- fetal condition indicator (FSI) – from 0 to 1.05;
- The Dawes/Redman criteria must be met, other indicators are not important.
The main thing in computer cardiotocography is an indicator of the condition of the fetus. It is he who characterizes the condition of the fetus based on the data obtained.
One of the important studies in the third trimester is CTG during pregnancy. This research method allows you to comprehensively assess the condition of the fetus, whether the baby is suffering from hypoxia. It is performed on almost all pregnant women in the third trimester, and especially in preparation for childbirth, as well as during the birth itself.
What is fetal CTG during pregnancy?
Cardiotocography is carried out during pregnancy in order to obtain data on the heart contractions and the work of the fetal heart in combination with its motor activity, contractions of the uterus and the reactions of the fetus to this.
Typically, this study in pregnant women is combined with ultrasound and Dopplerometry (a special study of blood flow in the vessels of the placenta, umbilical cord and fetus).
These examinations make it possible to identify any abnormalities during pregnancy that impede the normal development of the child, which will allow the doctor to prescribe treatment in a timely manner.
When is CTG prescribed during pregnancy?
Before this period, the fetal organs are still immature, and the data may not be entirely accurate and true. When performing CTG, it is desirable that the child is relatively calm, since the results obtained from CTG will also depend on his movements.
Therefore, the exact timing of the procedure will be determined by the doctor according to indications. Thus, the answer to the question at what time CTG is done during pregnancy will be from 30-32 weeks of pregnancy to childbirth.
How often is CTG done during pregnancy?
If the pregnancy proceeds without any complications, then CTG will not be frequent - they are prescribed no more than twice during the third trimester.
If any complications are detected during pregnancy, CTG is prescribed more often, up to daily monitoring - this study does not cause any harm to the fetus or mother.
In addition, CTG can be performed even during childbirth; this is required in cases where it is necessary to determine the general condition of the child and make a decision on further management of labor.
Children with complicated childbirth, entanglement in the umbilical cord, or other pregnancy pathologies will need special monitoring.
How is CTG done during pregnancy?
CTG during pregnancy is an absolutely safe and painless procedure. It will not harm either the mother or the fetus in any way. Carrying out CTG is especially interesting for those women who are encountering it for the first time and are wondering what they will do?
First of all, in the office, the doctor will ask the woman to take a comfortable position, lying or reclining, sometimes sitting, so that she can spend the next hour comfortably. It will be important to relax and behave calmly. Several sensors are attached to the stomach:
- one of the sensors is ultrasonic, it will record the fetal heartbeat;
- the second is a strain gauge, with which contractions of the uterine walls will be recorded;
- There may also be an additional sensor for movements or a button in the woman’s hand, which she presses with each distinct movement.
Cardiotocography is performed during the fetal activity phase; if the fetus is sleeping, the results may be questionable. The recording is carried out for 30 to 60 minutes, all data received by the device is recorded in the form of special graphs with teeth on special tapes.
There are modern devices that record and analyze graphs, producing results in a point system.
CTG during pregnancy: how to prepare
Although the procedure is not difficult, it requires some preparation.
First of all, a woman needs to get a good night's sleep and rest before the procedure; if a pregnant woman is stressed or tired, the results may be questionable or bad.
Before the procedure, you should have a snack, since you will have to sit for a long time without moving much, go to the toilet and relax, forgetting about all the problems and events.
Be sure to turn off your phone and not talk. Before the procedure, you should move a little so that the baby does not sleep, and the recording is successful.
It is worth making yourself more comfortable during the procedure so that in the future you do not change your body position too much and do not affect the recording, since on average, the recording lasts at least half an hour, and usually about an hour.
This is necessary to accurately determine the frequency of contractions of the fetal heart and the reaction to contraction of the walls of the uterus. The most reliable results are obtained in the absence of any problems during pregnancy.
Sometimes women receive a bad CTG during pregnancy, but feel great, and there are no deviations in the state of pregnancy; this requires a repeat study in order to exclude the fetal sleep phase and the influence of side effects on the results.
Usually, accurate results are obtained by completing at least 2-4 studies in a row if there are any deviations; conclusions cannot be drawn from one study!
CTG during pregnancy: normal
Modern devices can immediately issue a form with completed results and a CTG assessment. Good results are considered:
- the heart rate is in the range of 108-160 beats per minute when the fetus is at rest and 125-180 beats per minute when the fetus moves. In this case, a uniform heart rhythm should be detected;
- the heart rate ranges from 5 to 25 beats/min;
- heart contractions rarely slow down, and the decrease does not exceed 15 beats per minute;
- accelerated heart contractions occur no more than twice per study with an amplitude of no more than 15 beats per minute;
- the number of uterine contractions does not exceed the contractions of the baby’s heart by more than 15%.
The indicators are assessed by points, the sum of points is a maximum of 12 units. CTG with a score of 9 to 12 units is considered a good result.
If there are 6-8 points, repeated examinations and CTG are taken; if the result is stable, the child has mild, removable hypoxia.
With a score of 0-5, serious deviations in the development of the fetus are identified, hypoxia threatens its life and urgent measures are required. In this case, pregnant women are immediately prescribed therapy or decide on a caesarean section (if this is a CTG during childbirth).
CTG during pregnancy is an absolutely harmless procedure that allows you to relatively quickly and accurately assess the condition of the child, and during childbirth it helps with further labor management tactics.
Cardiotocography is a method of prenatal diagnosis of the condition of the fetus. The procedure is widespread because the research is simple to do and is safe for the mother and unborn child.
- fetal hypoxia;
- intrauterine infection;
- low or polyhydramnios;
- abnormalities in the development of the fetal cardiovascular system;
- premature maturation of the placenta or threat of premature birth.
If suspicions of deviation are confirmed, this allows the doctor to promptly determine the need for therapeutic measures and adjust the management tactics of the pregnant woman.
Preparing for the study
With proper preparation for the study, you can count on the most accurate results. You can reduce the time for cardiotocography if you eat before the study. It’s good if the snack contains fast carbohydrates, which increase blood glucose levels. For example, ice cream or sweet tea with a bun. An increased glucose level will wake up the baby and make him move more actively.
A successful decision before kgf fetus There will be a short walk in the fresh air, because during the study you will have to sit or lie still for a long time. It is for this reason that you should visit the toilet before starting the procedure.
Nervous strain and stress can negatively affect the results of the study. Try not to get nervous, if necessary, breathe in a calm rhythm.
How does the procedure work?
- First, the doctor, using a stethoscope (a special tube, one part of which the doctor inserts into his ears, and the second one applies to the mother’s stomach), determines the point at which the fetal heartbeat is best heard.
- Then an ultrasound sensor with Doppler function is installed at the point of best listening to the fetal heartbeat and fixed to the mother’s abdomen.
- After this, a strain gauge is installed in the area of the fundus of the uterus (that is, in the upper part of the woman’s abdomen), where uterine contractions are best detected.
In some cases, a woman may be given a special device with a button in her hand, which she will have to press at the moment when she feels the movements of the fetus. At the same time, other devices record movement data automatically. After all preparations are completed, recording and registration of CTG begins.
The received data is recorded on special paper, which is pulled out of the machine at a very slow speed. At the same time, you can see 2 curved lines on it.
The upper line characterizes the fetal heart rate (heart rate), and the lower line (tocogram) characterizes the contractile activity of the uterus. After a certain time, characteristic curves are formed on this paper, which the doctor examines when assessing the condition of the fetus.
How long does it take
The duration of the procedure is on average 30 - 40 minutes. However, in some cases, the study may end in 10 - 15 minutes or, conversely, last more than an hour.
The fetus moves intensely only during the waking phase, and during sleep it is relatively motionless, so it will not be possible to register “normal” cardiotocography. Under normal conditions, a child's sleep cycle lasts about 30 - 40 minutes; during a half-hour study, he should wake up for at least a few minutes and begin to move. If characteristic changes are recorded on the cardiotocogram, the study may not be continued.
It can be finished earlier if immediately after it starts the child moves quite actively. At the same time, if the fetus is inactive or asleep when the procedure begins, its duration can reach 60 minutes or more.
From what week is CTG done during pregnancy?
As a rule, it is prescribed from the 28th week of pregnancy. If there is a suspicion of a critical situation with the fetus, the study can be carried out earlier, but in these cases the device will only record the fetal heartbeat itself. It is not yet possible to assess how the baby reacts to uterine contractions, how the pattern of the heartbeat changes depending on the fetal movements themselves and some other factors. That's why , when to do kgt during pregnancy, - 28 weeks.
The price for the procedure varies:
- in Moscow the price can be from 1400 to 2000 rubles;
- in the regions - from 500 to 1000 rubles.
Today, most studies are carried out free of charge as part of the compulsory medical insurance program; it is necessary to clarify this information in the antenatal clinic.
Score in points
A gynecologist should decipher the results of the study, but if you have any doubts or questions, you can refer to this table to find out the approximate norms. It must be borne in mind that the indicators cannot be a reason for making any diagnosis, because this is only additional information about the condition of the fetus, and it is necessary to take into account the results of other tests and research methods.
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