CTG fetus — norm
Every woman during pregnancy, worries about the development of her child, whether it is in order. Today there are methods that allows you to reliably assess the condition of the fetus. One such method is the cardiotocography (CTG), which identifies the relationship between the perturbations of the fetus and the heart rate. In this article you will learn what CTG, what characteristics assess which indicators for CTG fetus — normal, and that affects the results of the study.
What is KTG
Cardiotocography is based on the detection frequency of fetal heart rate and its changes depending on the influence of external stimuli or activity of the fetus.
Diagnostics carried out using two ultrasonic sensors, one of which is fixed on the belly of pregnant women, pre-defining the area is nice hearing baby's heartbeat. It is intended for registration of cardiac activity of the fetus. The sensor senses reflected from the heart of a child an ultrasonic signal, which is then converted to an electronic system in the instantaneous heart rate. The second sensor secured to the abdomen in the region of the uterine fundus. It registers the contractions of the uterus. To improve the passage of the ultrasonic wave sensors are processed with a special gel. Modern devices are equipped with a remote button which pregnant women may be noted movement of the fetus.
The results are displayed by the device on the paper tape in the form of a graph. There are uterine contractions and fetal movements. The data obtained can be judged, primarily, on the state of the nervous system of the baby, its protective and adaptive reactions. If the indicators CTG fetus – normal, so the baby feels comfortable, and it is developing according to the terms.
Why do you need CTG
Examination of the pregnant woman in the office of the obstetrician-gynecologist includes listening to baby's heartbeat with stethoscope. Abnormal heart rate (heart rate) to more or less suggests that a child is experiencing discomfort. In this case, the doctor sends the mother on a more thorough study of the cardiovascular system of the fetus – CTG.
There is a strong correlation between the health of the pregnant woman and the fetus. So, if the pregnancy proceeded quietly, without intrauterine infection, threatened miscarriage, preeclampsia, the results of TPC are likely to be normal. If in good health pregnant results observed suspicious CTG, you must re-conduct a survey in a week.
If a pregnant woman found to have severe changes in health status, it is necessary as often as possible CTG in order to prevent the occurrence of abnormalities in fetal development and take necessary measures.
Features of the study
Assign CTG usually after 32 weeks of pregnancy, since only by that time there is the maturation of neuromuscular impulses, and the method is most informative.
For example, CTG fetal normal 33 week presence on the chart for more than two accelerate. By that time they are caused by the nervous system response to fetal movements or external factors. In the earlier stages of acceleratie can be associated with the conditions of the intrauterine existence of the fetus, so the research could lead to false results.
Also by that time the fetus is established, the cycle of activity and rest that is of great importance for this study. When conducting a CT scan of the dormant period of the fruit results will always be positive, even if in fact there is a high degree of hypoxia. That is why the study should be conducted for at least 40 minutes. During this time the fetus is bound to increase physical activity, allowing to register the change in heart rate during movement.
It is very important that a woman feel relaxed and comfortable during the study. Uncomfortable or vivid emotions can cause more active movement of the fetus, leading to false results. Usually during the procedure, a woman sits in a comfortable chair or lies on a couch on the side.
In order to understand how to decipher CTG fetus, analyze in detail, on what parameters to evaluate it.
Basal heart rate
Basal heart rate is the average heart rate of the fetus, designed for 10-20 minutes. Define it in the absence of motion of the fetus between contractions of the uterus without external stimuli, without taking into account accelerate and decelerate. When conducting CTG fetus BOSS the norm is 110-160 beats per minute. Tachycardia, that is, exceeding the basal heart rate, may occur with hypoxia, anemia, malformations and failure of heart function of the fetus, and when the febrile state of pregnancy, if she has a intrauterine infection, improving thyroid function. Taking medications that have a cardio effect, can lead to increased fetal heart rate.
The decrease in basal levels below normal (bradycardia) may be caused by hypoxia, heart defects of the fetus and low blood pressure of the mother, hypoxemia, prolonged compression of the umbilical cord, the presence of pregnant women cytomegalovirus infection.
Heart rate variability
This option is characterized by the instantaneous oscillation deviations of heart rate from basal levels. In the analysis of the CTG usually study the instantaneous amplitude of the oscillations, the nature of which emit low oscillations (the deviation is less than three beats/min), medium (3-6 beats/min), high (amplitude is more than 6 beats/min).
For CTG fetus Norma 36 weeks – high oscillations, attesting to the good health of the fetus. The presence of low frequency oscillations tells about the pathologies in his development.
Special attention in analysis is paid cardiotocogram slow oscillations. Depending on their amplitude distinguish between monotone type, which is characterized by low amplitude oscillations (from 0 to 5 beats/min), transitional type with an amplitude of 6 to 10 beats/min, wave (from 11 to 25 beats/min) and riding type (amplitude higher than 25 beats/min). The increase of the amplitude of the oscillations may be due to moderate hypoxia, and the influence of external stimuli, it stimulates the nervous system. Decreasing the amplitude of the oscillations can be caused by severe hypoxia, which leads to inhibition of the function of the nervous system of the fetus, the use of narcotic drugs, tranquilizers.
The acceleration is called temporary increases in heart rate at least 15 beats/min compared with basal level and duration more than 15 seconds. On cardiotocogram they look like high teeth. Acceleratie are a response to external stimuli, uterine contractions, baby's movements. Their availability to CTG of the fetus is normal.
Decelerating is the decrease in the frequency of fetal heart rate at least 15 beats/min lasting more than 15 seconds. The chart shows how significant depression. There are early, late and variable deceleration. In addition, their klassificeret amplitude as the lungs by slowing the heart rate to 30 beats/min, moderate – 30 to 45 beats/min, and heavy – from 45 beats/min Decrease in heart rate may occur as a result of violations of placental blood flow, hypoxia of the myocardium, compression of the umbilical cord.
CTG fetus. The norm indicators
To assess the status of the fetus the world health organization has developed guidelines that specify the minimum and maximum allowed values for each of the parameters. According to these recommendations, CTG fetus (normal for 33 weeks) should have the following values:
- Basal heart rate: 110-160 beats/min.
- Heart rate variability in the range of 5-25 beats/min.
- Two or more of acceleration for 10 minutes.
- The lack of deep decelerate.
It should be noted that for CTG fetal 35 weeks or more is the same as 33 weeks.
Assessment of the status of the fetus points
Transcribe the results to CTG on a 10-point system, assessing each criterion from 0 to 2 points. For CTG fetus the norm is 36 weeks and throughout the third trimester, is 9-10 points if the total number of points from 6 to 8, it says oxygen starvation (hypoxia) with no immediate threats, it is necessary to repeat the procedure a CT scan in a weekif 5 points or less – then the child experiences severe anoxia, which can lead to serious neurological problems that required emergency measures.
You need to remember that even if CTG fetus of 8 points or below, it is not necessary ahead of time to be frightened. In this study, as in many others, there are factors that affect the information content of the testimony. The results strongly depend, for example, a child is sleeping or awake. Experienced doctors in deciphering cardiotocogram take into account such factors as weather conditions, the mood of the pregnant woman, the level of glucose in the blood of women. If HIC data are abnormal, the doctor will prescribe additional tests. Usually cardiotocography taken twice in the third trimester of pregnancy, but in some cases more, for example, in multiple pregnancies, high blood pressure, infections, diabetes, poor ultrasound, bleeding, premature labor.
Possible errors in the interpretation of data CTG
- The child in the womb is in constant motion. Sometimes he can squeeze the head the umbilical cord, which in the short term disturbed blood flow in the vessels of the umbilical cord, which is reflected in the results of KTG. In this case cardiotocogram will have a pathological case of good condition of the fetus.
- Sometimes during oxygen starvation in the fetus included protective reaction, reduction consumability of oxygen by the tissues and increasing resistance to hypoxia. In such cases, the child suffers, but the KTG is not affected.
- With the development of pathology may decrease the ability of tissues to utilize oxygen at its normal concentration in the blood, causing the fetus does not occur any reaction, and be fine, although it suffers from the lack of oxygen.
Considering all the above, you need to understand that CTG fetus during pregnancy is a very important method of diagnosis, but to get the full picture data CTG should be compared with other studies. Today the widely used ultrasound diagnosis and Doppler.
Where do CTG fetus
CTG do for free in all antenatal clinics. It is possible to study in private medical centers, but on a paid basis.
Hospitals also carry out cardiotocography during labour and delivery. This helps to assess the health of the child during birth and uterine contractions, to test the efficacy of the treatment and tactics of childbirth.
Some expectant mothers are afraid to spend different kind of research during pregnancy, believing that they can harm the health of unborn baby. Cardiotocography is completely safe, and you can do it as many times as necessary, without risk to health. In addition, it is painless, does not cause any discomfort.
We wish you an easy pregnancy and good health!