Interpretation of CTG during pregnancy: norm and pathology. Helpful information

Today, modern equipment, which is now used in medical institutions, has reached such heights that it allows us to diagnose most diseases of our body, even at very early stages formation.

Expectant mothers are especially sensitive to their bodies. Thanks to modern technologies pregnancy can be monitored already in the early stages of fetal formation; we can monitor its development and control the course of this process if we suspect any deviation from the norm. Today, cardiotocography is used for early recording of the fetal heartbeat.

CTG

This method of examination allows not only to record the fetal heartbeat in the uterus, but also to mark on the curve any movement (contractions of the uterus or the fetus itself), the influence of environmental factors (signs of hypoxia), and to identify a delay intrauterine development and other more complex pathologies.

When using the device, uterine contractions and fetal heartbeat are simultaneously monitored. This approach makes it possible to comprehensively and fully assess the reactivity of the fetal heart muscle (the possibility of changes in heart rate under the influence of external factors). There are 2 types of cardiotocography, which differ in the way they obtain information:

External CTG. The sensors are applied directly to the skin in the area of the pregnant uterus (without violating its integrity). Measurements are carried out using ultrasound (heartbeat detection) and strain gauge (uterine tone) sensors. This type of CTG has no contraindications and is used in most clinics.
Internal CTG. Applies only in birth period and very rarely. To measure the heartbeat, an ECG electrode is used, it is fixed on the fetal head, and a strain gauge is installed directly into the uterine cavity.

The examination itself can be carried out by nursing staff (nurse or midwife). To obtain the necessary data, it is necessary to correctly install highly sensitive devices on the skin of the abdomen (at special points) and turn on recording. But only a trained doctor can decipher the results.

When is CTG performed during pregnancy?

As already written above, cardiotocography is used for timely diagnosis of fetal malformations. The most suitable period for this is 27–29 weeks of pregnancy. This method is used:

Once or maximum twice, if there are no deviations from the normal course of pregnancy.
If obvious deviations from the norm are detected or if the pregnant woman complains of fetal immobility.
If the previous pregnancy ended unfavorably (complicated obstetric history).
When identifying chronic diseases or when they worsen.
With gestosis.
With active abuse of tobacco or alcohol.
With a post-term fetus.
At the time of delivery (expulsion period).

If there is any suspicion of deviation from normal course pregnancy, it is better to play it safe and perform a repeat study. How is CTG done during pregnancy in any hospital?

Principles of research

For use this method need to wait certain period pregnancy. The very first referral for cardiotocography is issued at least 28–30 weeks. If the period is shorter, then the received data will be extremely difficult to decipher. At normal course pregnancy CTG prescribed 2 times in the third trimester, and if any pathology is detected or to clarify the data, additional studies can be prescribed. Basic rules before the study:

A pregnant woman should rest for some time after going to the hospital.
Before monitoring, you can eat, but do not overeat.
The recording is performed on the condition that the fetus is not sleeping. Most often, mom knows when he is most active and when he is “silent.”
The procedure itself lasts about 30–40 minutes, so it’s better to go to the toilet prematurely.
During diagnosis, pregnant women lie on their side or back, whichever is more comfortable for them.
The sensors should not be touched with hands at the time of registration; if possible, avoid laughter and other emotional experiences. An increase in blood pressure or abdominal pressure may change the CTG picture.
After assessing the results, the doctor attaches the tape to the pregnant woman’s card. By the end of pregnancy, the chart should have several cardiotocograms.

A bad CTG during pregnancy is not a reason to become depressed and worry excessively. Repeated examination in most cases shows normal fetal development. The main question for mothers who see such a document for the first time is: “what does CTG show?”

Interpretation of CTG during pregnancy

The results of the study are presented on the tape in the form of a curved line on which positive and negative teeth are marked. It displays work data fetal heart(heart rate, rhythm, presence of hypoxia) and periods of contraction of the pregnant uterus. There are several ways to read CHT, the most accessible of them is the Fisher method. To read you need to highlight:

The basal rhythm is the average heart rate of the child (normally 110-155 beats per minute). One of the signs of hypoxia is an increase or decrease in this indicator.
Fluctuations in heart rate are expressed as amplitude and variability. Normal fluctuation varies between 10–30 beats per minute. On the device, this figure is constantly changing, but does not go beyond the established limits. If the amplitude decreases or is not initially high, then this tells us that the fetus is sleeping or there are signs of a pathological condition.
Acceleration is an increase in heart rate lasting up to 1 minute. This figure depends on the tone of the uterus, its contraction and the mobility of the child. A similar process is observed in adults during physical activity.
Deceleration is a decrease in rhythm frequency, lasting up to 1 minute. Deviations of this indicator from the norm may indicate an umbilical cord entwined around the neck. Normally, the indicator should not change.
If you count the number of teeth in 1 minute, you can determine the frequency of changes. The norm is approximately 5–10 teeth.
Counting movements per hour. Normal fetus should make approximately 10 movements per day.
For the total calculation of data, the doctor assigns a sign from 0 to 2 points (normal - 2, deviations - 1, critical indicators - 0 points).

All the results obtained are added up and a certain table is formed. From 10 to 8 points - this is the normal physiological state of the fetus and uterus, with deviations. From 7 to 5 points – signs of hypoxia; this condition requires medical intervention and monitoring; for reliability, ultrasound examination and repeated CTG are performed. If the result is 4 points or less, then the fetus is experiencing an acute pathological condition, it is necessary to carry out drug treatment, repeated ultrasound and CTG. At 36 weeks decoding CTG The fetus is not difficult for a specialist, since this period allows you to clearly localize and determine when the mother’s uterus contracts and how the baby’s heart beats. It is difficult to do this at earlier times, since the sensors cannot detect heart contractions and the results obtained are “blurred”, without providing reliable information.

Harmfulness

Many studies have been conducted that have proven that the effects of the device’s sensors are absolutely harmless for both the fetus and the mother. Some women note that during the procedure, the baby in the stomach “calms down” or, on the contrary, “activates”, this is due to the fact that the sound that the sensor makes is new for the baby and causes discomfort. A pathological recording can be made in the following cases:

Overeating before the procedure. Excess food can affect the well-being of the child and mother, causing changes in the tape.
The child is sleeping at the time of diagnosis.
With an increased maternal body mass index. Excessive fat will prevent the sensor from recording signals from the baby’s heart.
Increased physical activity child.
If the gel is not applied sufficiently to the sensor area.
During recording, the sensor may move away or move.
If there is a multiple pregnancy.

If repeated recording does not improve the quality of the data obtained, then the pregnant woman is sent for an ultrasound examination. The result of an ultrasound examination shown to the doctor will refute or confirm the presence of pathology.

Hello, dear readers! Pregnancy is not a disease, but just a temporary and rosy state. Nevertheless, the health and life of the unborn baby often depends on its course. And even if they are entirely in the hands of nature, at a critical moment doctors will still be able to do something.

True, provided that the danger is identified in a timely manner. This can be done today in several ways, including absolutely safe ones. One of them is fetal CTG. What is it, when, why and why is it prescribed? This is what we will talk about. And at the same time we’ll find out whether we should be afraid of him.

CTG, or cardiotocography is a method of assessing the general condition of the fetus during pregnancy and childbirth by listening to its heartbeat at rest, activity, exposure to any external stimuli or contractions of the uterus.

How long does CTG take? Ideally, it should be carried out starting from the 28th week of pregnancy. But in practice, doctors prescribe CTG at 32 weeks and later, justifying their decision with the low information content of the method in the early stages. However, during the third trimester, if all is well, the woman undergoes this procedure at least twice.

In some cases, the number of visits to a specialist performing CTG can be increased significantly.

This is about:

suspected pathologies of fetal development;
unsatisfactory results of previous studies;
a woman’s complaints about the baby’s low physical activity;
the presence of various diseases;
aging of the placenta;
umbilical cord entanglement;
post-term pregnancy, etc.

By then comparing the results of CTG with the results of ultrasound and Doppler, specialists exclude or confirm the development of hypoxia and pathologies of the baby’s cardiovascular system.

As a rule, a referral for CTG can be obtained at the antenatal clinic, but if you don’t want to stand in lines or want to make an appointment for a specific time, you can register online and get examined at any good clinic.

Along with this, cardiotocography allows us to identify:

fetoplacental insufficiency;
intrauterine infection;
low or polyhydramnios;
premature maturation of the placenta;
risk of premature birth.

During childbirth, CTG makes it possible to monitor the baby’s heart rate and is necessarily carried out in cases where there is an entanglement of the umbilical cord.

2. How CTG is done during pregnancy

The procedure itself is absolutely painless, but takes about 20–50 minutes, depending on the quality of the results obtained. All this time, the woman needs to be at rest and move as little as possible so as not to provoke the sensors to fall. And, perhaps, this is its only drawback.

Cardiotocography is performed using a special apparatus. It is a combination of a strain gauge, an ultrasonic sensor and an electronic cardiac monitor system. Of course, the first two are attached to the pregnant woman’s belly, while the latter allows you to directly record the heart rate, as well as uterine contractions, analyze them and produce the finished result in the form of a long tape with graphs.

How to prepare for CTG? Just eat a little before the ceremony and preferably something sweet. This will make the fetus move more actively. True, you shouldn’t go to extremes and overeat. Significant fluctuations in blood sugar levels can have a very negative impact on the result, as can overexertion and stress. Therefore, it is undesirable to be nervous directly at the time of the procedure.

It is extremely important to take a comfortable body position - semi-sitting or lying on your left side and wait until the specialist attaches the ultrasound sensor to the anterior abdominal wall, and the strain gauge to the area of the right corner of the uterus. The latter is necessary to assess fetal behavior during uterine contractions. From this moment the recording will begin. If the results are satisfactory, expectant mother will be sent home. If something alerts the specialist, he will most likely insist on performing stress cardiotocography.

3. What is stress cardiotocography

This is a procedure that is carried out using two tests that simulate the birth process, namely:

oxytocin stress test– it involves the administration of an oxytocin solution to stimulate labor activity and monitoring the behavior of the fetus at the time of contractions;
mama dough, or endogenous stress test. It involves stimulation of the nipples by twisting them with your fingers, which also causes contractions. It is worth noting that this test is safer and has virtually no contraindications.

But additional research may include other tests that directly affect the fetus.

We are talking about:

acoustic test– it provides for the presence of a sound stimulus, in response to which changes occur in the cardiac activity of the fetus;
fetal palpation– when there is a limited displacement of its presenting part, the head or pelvis, above the entrance to the pelvis.

4. Decoding CTG

It is worth noting that CTG results do not provide a specific diagnosis. They only enable the doctor to assess the baby’s health status, thanks to another study, during which certain indicators are recorded:

Heart rate- heart rate;
basal heart rate (BHR)– these are heart contractions that are recorded in the intervals between contractions or persist for 10 minutes;
change or variability basal rate;
acceleration– acceleration of heart contractions, fixed for 15 seconds or more by 15 or more beats;
deceleration– accordingly, a slowdown in heart contractions, recorded at the same period of time and in the same volume.

Normally, CTG results should be:

basal rhythm – 120-160 beats per minute;
basal rate variability – 5-25 beats per minute;
accelerations – 2 or more during 10 minutes of recording;
decelerations are rare, shallow or absent.

To simplify the process of their interpretation, doctors use a point system.