Which CTG values are normal?
introduction
A Cardiotocogram, short CTG is used to measure the child's heart activity and the maternal labor. Overall, this procedure is used to monitor the late pregnancy or the birth used himself.
The heart activity of the unborn child is monitored using Doppler ultrasound measured and recorded as heart rate. The mother's labor is performed with the help of a Pressure sensor measured, which registers the change in waist circumference during a contraction.
Depending on the physical constitution of the pregnant woman, the pressure measurement can vary and not provide very accurate values. Therefore, in addition to the actual measurement, there is also subjective feeling important about the perception of labor by the pregnant woman.
It is best for the expectant mother for the duration of the examination laterally or on the back lie. Usually two belts are placed around her stomach, which are supposed to hold the respective measuring sensors on the abdominal wall. As a rule, the sensors are connected to the actual device for recording via a cable. The measured data can be printed there on paper strips. With modern devices, data transmission is also possible via radio, so that the woman can move freely during the examination.
The cardiotocogram also enables a statement to be made about the child's heart rate by measuring the heart rate Oxygen supply to the unborn childwhat is essential for physical development. If the heart rate drops, for example, this is to be interpreted as a direct sign of an insufficient supply of oxygen and should be remedied as quickly as possible so as not to endanger the health of the unborn child.
Standard values
The child's heart activity is given as heart rate in beats per minute. Usually it should be between 110 to 150 strokes per minute (also: Beats per minute, in short: bpm) lie. Towards the due date, this can even increase a little, usually up to 160 bpm. The basic frequency corresponds roughly to the resting heart rate of the adult and is used as a Baseline designated.
values below 110 bpm correspond here medically to a Bradycardia (so a slowed heartbeat), Values over 150-160 bpm one Tachycardia (a heartbeat that is too fast). If such a condition lasts longer, the cause should definitely be further clarified.
In order to determine further normal values for the CTG examination, a more detailed examination of the individual changes in the child's baseline is first necessary.
During the examination, in addition to the baseline itself, their Fluctuations (Oscillations) and whether it changes over long periods of time (Accelerations / decelerations).
The heart rate is not always constant, even in unborn babies, but should not be more than about 15-20 bpm from one Average frequency differ. On the CTG curve, this phenomenon is expressed as a curve with small peaks. If, on the other hand, the heart rate were always constant at one value, you would have a straight line.
Such oscillations usually occur particularly when the child's situation changes. On average, every minute of the CTG recording should be about three to five such oscillations can be measured.
A longer one rise the base frequency is in the CTG as Acceleration referred to, a Slowdown however as Deceleration. It is important that the change in baseline is more than 15 bpm and lasts longer than 15 seconds. Accelerations are also a sign of that Liveliness and healthy activity of the child. Normally should be about 2 accelerations per 30 minutes of CTG measurement occur.
Decelerations, that is, slowdowns in heart rate, are also synonymous with Dips designated. Depending on the size of the waste, synchronicity with contractions and the duration of the decelerations, a distinction is made between different levels. Some of them are rather than harmless to classify, others, however, can sign a Insufficient supply be.
The labor activity is called Tension on the abdominal wall measured, which usually changes during contraction during labor. However, depending on the physical constitution of the mother, this measurement is not always very precise, which is why the woman's subjective perception is very important for the assessment. On the CTG recording you can then size, regularity and Duration of labor further assess.
Heart sounds
With the help of the child's heart sounds, the heart rate of the unborn child can be determined on the cardiotocogram (in short: CTG) be determined. This is done technically with the help of a Doppler ultrasound, from which a signal is sent and the time is measured until the signal is reflected from the child's heart and reached the sensor. From this period of time it can then be calculated how quickly the childlike heart activity is current. The measuring sensor is usually a special microphone, which is also known as a Doppler ultrasound transducer.
The advantage of this method is certainly that a "live“- Supervision of the child from the outside by a complete non-invasive procedure can be done. However, as a result of the indirect measurement, the method is also particularly susceptible to the smallest disturbances, such as movements of the child or mother.
It is therefore important to have at least one CTG examination half a hour to be carried out continuously for a long time in order to be able to obtain a meaningful overview. Ideally, the mother should also lie down as calmly and relaxed as possible and not move much during the examination.
When should CTG values be determined?
This examination is usually only from the 30th week of pregnancy carried out. All 14 days If there are no other abnormalities, it will usually be within the normal range Checkups repeated until the actual due date. By default, this investigation should under childbirth done in all women.
In principle, the CTG is more for them monitoring the advanced pregnancy or the birth process makes sense. In the event of a premature birth or risk constellations for the mother like a Diabetes mellitus, high blood pressure, Infections, vaginal bleeding or Abnormalities of the child In the ultrasound, a CTG examination should be performed from 25th week of pregnancy respectively.
If the unborn child is transmitted, i.e. if the pregnancy continues after the calculated delivery date, the CTG examination should also be performed in shorter time intervals be repeated.
Before the birth itself will routinely a cardiotocogram (in short: CTG) in order to better monitor the child's condition before birth. In particular, it measures to what extent the child reacts to labor and whether it has properly adjusted to the imminent birth. Usually it is then at a distance of about two hours a 30 minute CTG was recorded each time.
If there is any indication that the child is at risk in the womb, the CTG examination can also be carried out for a longer period of time, possibly even continuously until the birth.
Learn more about the topic at: Labor recorder
During labor
It can be synchronized with the mother's contractions Decelerations or Dips the child's heart rate come. Physically this can be explained by the fact that it leads to during a contraction Compression of the abdomen the mother comes so that the blood supply and thus the oxygen supply of the child is temporarily cut off. If the contraction is severe enough, a deceleration of the child's heart rate can be observed in the CTG at the beginning of the contraction. If this is the case, this speaks for a rather good response of the child on labor. However, one further differentiation the dips must be done.
Are the dips more likely irregular, just last short on (under 30 seconds) and kick independently from contractions on, they are as completely harmless to classify. Decelerations that occur roughly synchronously with the onset of labor are also to be viewed as a good sign and indicate that the child is responding well to the labor. The baseline should reach its maximum deflection around the peak of the contraction itself and return to around the average starting value after the contraction.
Delayed or long-lasting dips, on the other hand, can be a sign that the child is not receiving enough oxygen and possibly one Induction of labor should be considered.
