In cardiotocography, a tocographer uses an ultrasound tansducer and a pressure sensor to record the heartbeat of an unborn child in relation to the labor activity of the expectant mother, which is primarily intended to ensure the health of the child during delivery. The data measured in this way are displayed in a cardiotocogram and, after evaluation using schemes such as the Fischer scores, are used by obstetricians, for example, to assess the potential need for a cesarean section. To some extent, cardiotocograms also take place during pregnancy, but they are recommended outside of childbirth only in exceptional cases because they often trigger false alarms and could thus prompt the physician to induce labor unnecessarily early.
What is cardiotocography?
Cardiotocography is a gynecologic monitoring procedure that can map the heartbeat of the unborn child in relation to the labor activity of expectant mothers. Cardiotocography is a gynecological monitoring procedure that can map the heartbeat of the unborn child in relation to the labor activity of expectant mothers. Konrad Hammacher is considered the inventor of the procedure, which is now one of the standard procedures in the field of pregnancy monitoring during an ongoing birth. As a rule, cardiotocography is an external, i.e. non-invasive, procedure and takes measurements through the mother’s abdominal wall. An ultrasound transducer and a pressure sensor work together in cardiotocography. They send a sound into the womb that reaches the baby’s heart and throws back an echo that is used to calculate the heart rate. The tokograph outputs the measurement data in the form of a cardiotocogram, which lets obstetricians detect any complications or problems early enough during the birth and fix them afterwards.
Function, effect and goals
Cardiotocography is performed primarily during the first 30 minutes of a birth to ensure the health of the unborn child. If there are no abnormalities on the cardiotocogram during these first 30 minutes, obstetricians usually turn off the machine and do not record the readings continuously again until the late opening period. The probes of an ultrasound transducer and a pressure sensor are attached to the expectant mother’s abdomen to perform the measurement procedure. The ultrasound transducer lies under an abdominal bandage, where it remains movable and can thus be adjusted to the position of the unborn child. The transducer eventually sends sound waves into the womb, which reach the unborn child’s heart and trigger an echo there. The echo reflected back is registered by the transducer’s receiver and is used to calculate the heart rate. Modern ultrasound transducers are also capable of registering fetal movements. Since the heart rate of the fetus is to be displayed in cardiotocography in relation to contractions, the pressure sensor measures the contractions of the uterine muscles at the same time. The device derives these values from the abdominal wall tension of the expectant mother and records the data calculated in this way. As a result of oxygen deficiency, the fetal heart rate sometimes decreases sharply. Such so-called decelerations can be documented by cardiotocography and may require a cesarean section. In particular, late decelerations following each contraction are an indication that the fetus is at risk. Early and thus labor-synchronous decelerations, on the other hand, are usually harmless as long as they have been present since the beginning of the birth and do not occur suddenly toward the end. In order to evaluate the measured data of cardiotocography, schemes such as the evaluation in Fischer scores are used. In the near future, evaluation will be largely computerized according to accepted guidelines.
Risks, side effects, and hazards
In addition to its use at birth, physicians sometimes advise cardiotocography in late pregnancy. In particular, this may occur in high-risk pregnancies. However, many experts advise against cardiotocography during pregnancy, as complications have arisen in the past precisely because of the procedure. For example, cardiotocography can trigger false alarms and cause the doctor to induce birth without justification.When cardiotocography is used within pregnancy as it is sometimes done in women with diabetes or hypertension to monitor any risks, an experienced and competent physician is essential to evaluate the cardiotogram. Abnormal findings should always be clarified by further examinations before the physician initiates measures. In fact, abnormalities are often due to normal processes such as fetal movements. However, cardiotocography is also rightly used during pregnancy in the case of previously registered disturbances of the heart rates or if there is a risk of premature birth. During the birth itself, the measurement finally counts as standard and is not associated with increased risks or side effects for either the mother or the unborn child. On the whole, the procedure is completely painless for the mother, but the unborn child should not be exposed to sonic energy for an unnecessarily long time during birth, if possible. The obstetricians must always take into account the mother’s constitution and her indications of labor activity when interpreting the recorded data, since the tocograph records even slight labor activity with high spikes, for example, in the case of the strong abdominal circumference changes of a very slim pregnant woman. In conclusion, an obese pregnant woman may lack rashes even though labor activity has long exceeded the norm.
