CTG or cardiotocography is a method of research in obstetrics, which is a synchronous recording of the fetal heartbeat and contractions of the uterus in 10-15 minutes. An objective indicator of fetal status in CTG is a change in the fetal heart rate at the time of contractions. Now, mainly indirect (external) cardiotocography is used: two sensors are placed directly on the abdomen of a pregnant woman - one in the area of the generating uterus contraction (most often the zone next to the right ovary), the second - in the area of best fetal hearth drying (depends on the type, position and the nature of the fetus present).
When evaluating CTG, the following indicators are taken into account:
- basal rhythm of fetal heartbeats;
- Variability of fetal heart rhythm;
- Accelerations - associated with uterine contractions or movements of the fetus increase in heart rate by 15 or more beats per minute, duration of not less than 15 seconds;
- deceleration - a decrease in the fetal heart rate during movement or fights.
Cardiotocography of the fetus - transcript
To facilitate interpretation of the results and decrease the role of the human factor in this study, in the midwifery practice, the Fischer score was used to decipher the fetal fetus. This methodology involves a ballistic evaluation of each of the indicators by such criteria:
- 0 points - marked signs of fetal suffering;
- 1 point - initial signs of violations;
- 2 points - normal performance.
About each parameter in order
The basal rhythm of the fetal heartbeats is recorded between fights, and displays the fetal status at rest. The normal range for this indicator is 110-170 beats / min, which corresponds to an estimate of 2 points. Boundary with a normal range, but already indicative of minor violations - 100-109 bpm, or 171-180 bpm, and 1 point, respectively. And the threatening condition for the fetus is a basal rhythm of less than 100 beats / min. or more than 180 beats / min.
The variability of the fetal heart rate is assessed by recording the amplitude and frequency of the oscillations, with an estimate of their amplitude and frequency (ie, the difference in the fetal heart rate with its movements or fights relative to the basal rhythm and frequency of these changes). Normal for the fetus are oscillations with an amplitude of 10-25 beats per minute, and a frequency of more than six episodes per minute, which corresponds to 2 points according to Fischer. Acceptable, but alarming are the values of the oscillation amplitude of 5-9 bpm, or more than 25 bpm, at a frequency of 3-6 episodes per 1 minute, which is estimated at 1 point.
Threatening indicators are changes in the amplitude of less than 5 bpm, with a frequency of such changes less than 3 episodes per minute, which is estimated at 0 points, and indicates the distress of the fetus.
With regard to the frequency of occurrence of the acceleration , measured over a period of at least 30 minutes, the norm for the fetus is the emergence of more than 5 accelerations in a given time interval, which is estimated at 2 points. Occurrence of periodic accelerations, with a frequency of 1 to 4 in 30 minutes is considered acceptable, but prognostically unfavorable, and is estimated at 1 point. Absence of accelerations at this time indicates a serious violation of the fetus.
Concerning the opposite phenomenon - deceleration - the norm is their registration in the first 5-10 minutes of recording or total absence - the norm and 2 points. The presence of significant variability in the occurrence of decelerations or their occurrence after 15-20 minutes of CTG recording means deterioration of the fetus and is estimated at 1 point. Repeated throughout the period of recording CTG desereration or a significant variety of them - the indicator of fetal distress and indicates the need for medical intervention in the course of childbirth.
When summing the scores for each indicator, we get the total points of the CTG of the fetus - a maximum of 10, a minimum of 0-2 points. Indicators mean:
- when evaluating the CTG of a fetus, 10-8 points is considered a variant of the norm and a favorable prognosis for the outcome of labor;
- CTG of the fetus of 7 points or less indicates an easy distress of the fetus, which requires further monitoring of the doctor for the newborn both during childbirth and in the postpartum period;
- CTG of the fetus is less than 4 points - it indicates a fetal condition and is an indication for immediate delivery by caesarean section or active obstetrics tactics with stimulation of labor.