Cardiotocography (CTG)


CTG is the abbreviation for cardiotocography or cardiotocogram. This is a procedure that can be used during pregnancy and childbirth to register and record the mother's labor on the one hand and the heartbeat of the child on the other.
The device with which this is carried out, the cardiotocograph, is also called a contractions recorder or heart pain recorder. It evaluates the incoming signals and rewrites them into curves, which can then be evaluated by a doctor or a midwife. The primary purpose of the CTG is to be able to recognize a possible lack of oxygen supply to the child at an early stage and to be able to react accordingly.

Read more on the topic: Labor recorder

Areas of application of the CTG

A CTG is usually performed during the birth process. It is started once the contractions are regular and strong enough. After about 30 minutes, the CTG is first interrupted and then repeated at regular intervals. At the end of the birth, the CTG is continuously recorded in order to be able to detect any oxygen deficiency in the child at an early stage.

A CTG is also routinely carried out by some doctors from the 30th week of pregnancy during the antenatal examinations. However, according to maternity guidelines, this is not mandatory. However, in the case of high-risk pregnancies or the threat of premature birth, a contraceptive recorder can be connected from the 25th week of pregnancy to evaluate the heartbeat and contractions. A CTG is also performed during pregnancy if the mother has pre-existing conditions, such as high blood pressure or diabetes mellitus, or if you are taking medication to prevent labor.

When should a CTG be written?

The CTG is part of prenatal care and is usually only used towards the end of pregnancy, usually from the 30th week of pregnancy, here it is particularly suitable for routine measurement of the child's parameters shortly before and during childbirth as well as labor.
The exact recommendation for a CTG often depends on how the pregnancy goes. There is a tendency for CTG examinations to be performed more frequently as pregnancy progresses. However, they often do not provide any additional information about the child's condition if one assumes a pregnancy without complications.
If, on the other hand, complications such as abdominal trauma occur, CTG examinations can also be carried out from the 25th week of pregnancy.

Do additional CTGs make sense?

Additional CTGs that are not anchored in the guidelines make no sense from the synopsis of the expected health of mother and child and the economic perspective, which is why they are not provided for in the guidelines.
Additional CTGs are therefore usually only carried out if there is an indication (signs) for additional monitoring of the unborn child. Further CTG's can be carried out, but often have to be paid for yourself (if there are no medical indications (signs)) depending on the health insurance company.

How does the CTG work?

The CTG method is based on the Use of ultrasonic waves. These are harmless for mother and child and pose no radiation exposure The pregnant woman is asked one Belt with two sensors around the stomach to put on. With this she can either sit down or lie on her side on a couch. On the one hand, the sensors register the Heart sounds of the unborn child (cardiogram), on the other hand the Length, intensity and frequency of labor the expectant mother (Tokogram). The registered values ​​are used by the Heart soundlabor recorder evaluated together and recorded in the form of curves. The heartbeats can be seen in the upper line, the contractions in the lower line.

The Heart sounds of the child will be about a special microphone recorded. This sends ultrasonic signals that are sent back by the child's heart and then received by the sensor. The curve of the heart tones depends on many factors that can complicate the evaluation. The curve is different depending on whether the child is currently in a waking or sleeping phase. Also play possible illnesses or medication of the mother a major role. This should definitely be taken into account in the evaluation.
The labor activity is determined by the tension in the abdominal wall. With every contraction, the uterus contracts and presses against the abdominal wall.

How are contractions measured in the CTG?

There are two possibilitiesto measure the labor of the expectant mother. Usually this is over indirect pressure measurement determined. The Changes in waist size and the increasing tension registered when the uterus contracted. The accuracy of the measurement is very much dependent on the woman's physique. In very obese women with a high percentage of body fat, labor measurement is difficult. In contrast, in very slim women, the waist circumference changes very significantly during labor.

During birth, after the amniotic sac has opened, the Pressure in the uterus measured directly become. However, this procedure is rarely used.

The contractions are recorded in curves and given in numerical values. These values ​​differ from woman to woman. Overall, the higher the rashes, the stronger the labor and the closer it is to delivery. It is impossible to say exactly how high the deflections go. With some women values ​​below 20 are registered at the beginning of the examination, with others the values ​​are already between 80 and 100. That too Values ​​during childbirth vary greatly. While the contractions recorder shows relatively low values ​​around 40 for some women, it shows up to 150 for others.

How does the CTG change during labor?

The CTG (cardiotocogram) is used to record the child's heartbeats and the uterus' contractions. The two parameters are recorded in different curves.
During labor, the curve that records the contractions changes.This curve shows the pressure exerted by a contraction causing the line to rise on the CTG. At the end of the contraction, the line drops again and returns to the zero line (no contraction).

Since the child also reacts to labor, changes in the child's heart action also occur: Normally, as an expression of the child's stress and movement, the fetal heart rate should increase by more than 15 beats per minute. This is also called acceleration. Acceleration is therefore always desirable.
If, on the other hand, the child's heart rate slows down by more than 15 beats per minute, it is deceleration. A distinction is made between early and late decelerations. Early decelerations are contemporaneous and not worrying. Late decelerations occur after the contraction peaks and can indicate that the fetus is not getting enough oxygen. They are therefore always in need of clarification.

When does labor start?

Labor pains can already from the 20th to 25th week of pregnancy occur. In these cases it is so-called Exercise contractions or Braxton-Hicks contractions. This type of labor is right painless and irregular. If these occur during a CTG, the values ​​that these training pains can assume are very different. Depending on the woman's physique, the rashes of the CTG can be very small and below values ​​of 20, or they can already climb up to values ​​of 100.

The registers especially in very slim women Labor recorder the rashes very extreme. Come this quite strong labor often, so it exists Risk of premature birth. From about the 36th week of pregnancy kick the Pangs on that by a higher deflection of the CTG Marked are. The real ones Labor pains are then from one dilated cervix accompanied.

What are labor pains and how do you recognize them in the CTG?

Exercise contractions are contractions in which the uterine muscles are already tensed.
However, contractions do not yet serve to expel the child from the uterus and are therefore less powerful and less targeted than the “real” contractions. Typically, the exercise contractions can also be recorded in the CTG, but they are associated with a smaller deflection of the contractions pressure curve. In addition, labor pains occur much less frequently and at irregular intervals. Due to their lower force, in contrast to labor pains, there is also a lower reaction of the child (i.e. the child's heartbeat) to the exercise contractions.

Can you see contractions in the CTG that you can't feel yourself?

The CTG is very sensitive to small changes, which is why it can already record the child's heart actions through the mother's abdominal wall.
It can also feel small rashes in the muscles in the uterus (small contractions) that you cannot feel yourself. This is typically shown by small and often brief increases in the pressure curve on the CTG.

How are heart sounds measured in the CTG?

The Heart sounds of the unborn child are also determined as part of a CTG in addition to the labor of the expectant mother. This is done by a sensor that is placed on the woman's stomach. This sensor sends Ultrasonic waves that are reflected from the child's heart. The recurring signals are registered by the sensor and recorded in the form of curves.

The child's heart sounds will be given in beats per minute and the normal value is between 110 and 150 beats per minute. Depending on whether the child is sleeping or waking, the frequency of the heartbeat can vary. At the time of Childbirth can the heartbeat up to 160 beats per minute. By registering the heartbeat you can Conclusions about the oxygen supply of the child. During the birth there is often a temporary lack of oxygen, which results in a decrease in the fetal heart rate. this will Deceleration called.