Norm on screening ultrasound 1 trimester
With the onset of pregnancy, a lot of questions start to bother a woman. Every future mother wishes her baby normal formation and development. In the early stages, there may be risks of developing certain diseases of the embryo. To investigate the condition of the baby, doctors prescribe screening for the first trimester. A woman can get the norms on ultrasound (a photo of the examination usually attached) from a specialist who is observing it.
What is perinatal screening?
Perinatal screening involves the study of a pregnant woman, which allows to identify the various defects of the child at the stage of intrauterine development. This method includes two types of examination: biochemical blood test and ultrasound examination.
The optimal time limit for conducting such a survey has been determined - it is a period from ten weeks and six days to thirteen weeks and six days. There is a certain standard for screening ultrasound of the first trimester, which compares the results of a survey of a pregnant woman. The main task of the ultrasound at this time is to identify serious malformations of the embryo and identify markers of chromosomal abnormalities.
The main anomalies are:
- size TVP - the thickness of the space of the neck area;
- underdevelopment or absence of nasal bones.
Ultrasound during pregnancy can detect the signs of a disease such as Down syndrome, and some other pathologies of the fetus. The rate for screening (ultrasound) 1 trimester should be analyzed up to 14 weeks. After this period, many indicators are not informative.
Screening for the 1st trimester: ultrasound rates (table)
To make it easier for the doctor to determine the condition of a pregnant woman, there are certain tables of indicators of the development of the baby’s organs. The ultrasound protocol itself is structured to understand the dynamics of embryo formation and growth. The article presents the norms of screening for the 1st trimester.
Decoding ultrasound (table below) will help to get information about whether everything is in order with the fetus.
Name of authority (criterion)
up to twelve weeks
Determination of embryo viability
To assess the viability of the embryo, it is very important to see the heartbeat in the early stages. In a small person, the heart begins to beat as early as the fifth week of being in the mother’s womb, and it is possible to detect it using the first trimester screening (the ultrasound rate) from the seven weeks of the fetus’s life. If at this time the heartbeat is not detected, we can talk about the likelihood of fetal death (missed abortion).
To assess the viability of the embryo, another heart rate is taken into account, which normally ranges from 90 to one hundred and ten beats per minute for a period of six weeks. These important indicators of screening for the first trimester, the norms of ultrasound together with the study of blood flow and body length should correspond to the reference data on the duration of pregnancy.
The more modern equipment used for the survey, the better you can see all the organs and get the most accurate results. If there is a high likelihood of congenital malformations or genetic developmental abnormalities, then the pregnant woman is sent for deeper examination.
In some regions, when registering in antenatal clinics, screening for the first trimester is mandatory for all pregnant women. Norms on ultrasound may not coincide with the results, so doctors immediately take the necessary measures to preserve the life and health of the child or mother. But most often, such a survey is sent to pregnant women at risk: they are women from thirty-five years old, those who have genetic diseases in the family and those who were born before have had miscarriages in previous pregnancies, stillborn children or a non-developing pregnancy. Careful attention is also paid to expectant mothers who have had viral diseases at the beginning of pregnancy, are taking dangerous medications or are exposed to radiation.
If a woman has bloody discharge in the first trimester, then an ultrasound scan makes it possible to identify the degree of viability of the child or his death.
Terms of pregnancy
Conducting additional tests to determine the exact duration of the state of pregnancy is indicated for women who have an irregular menstrual cycle or who do not even know approximately the date of conception of the child. For this, most trimester screening is used in most cases. Norms on ultrasound, decoding of the main indicators and the date of conception do not require special medical knowledge. A woman herself can see the expected date of delivery, the gestational age and the number of embryos. Basically, the number of weeks, determined by ultrasound, corresponds to the period, which is calculated from the first day of the female cycle.
In conducting the study, the doctor makes control measurements of the size of the embryo. The specialist compares screening rates for the first trimester with the data obtained. Decoding ultrasound occurs in the following parameters:
- measurement of the distance between the sacrum and the top of the embryo (7-13 weeks), making it possible to determine the actual duration of pregnancy using special tables;
- measurement of the length of the parietal bone of the head of the child (after 13 weeks), this is an important indicator in the second half of pregnancy;
- determining the size of the longest - femur of the body of the embryo, its indicators reflect the growth of the child in length (14 weeks), in the early stages it should be about 1.5 cm, and by the end of the child bearing increase to 7.8 cm;
- measuring the circumference of the abdomen in a child - indicates the size of the embryo and its estimated weight;
- determining the length of the head circumference of the ripening fruit, which is also used to predict the natural birth of a child. This measurement is carried out in the last stages of pregnancy, according to which the doctor looks at the dimensions of the pelvis of the future woman and the head of the child. If the head circumference exceeds the parameters of the pelvis, then this is a direct indication for cesarean section.
Definition of malformations
Using ultrasound in the first weeks of pregnancy reveal various problems in the development of the child and the ability to cure him before birth. For this purpose, an additional consultation of a geneticist is appointed, which compares the results obtained during the examination and the rates of screening for the 1st trimester.
Decoding ultrasound may indicate the presence of any malformations of the child, but the final conclusion is given only after the biochemical study.
Screening for 1 trimester, ultrasound rates: nasal bone
In an embryo with chromosomal abnormalities, ossification occurs later than in a healthy one. This can be seen as early as 11 weeks when screening for the first trimester is conducted. Norms on ultrasound, the decoding of which will show whether there are deviations in the development of the nasal bone, help the specialist to determine its value from 12 weeks.
If the length of this bone does not correspond to the gestational age, but all other indicators are in order, then there is no reason for concern. Most likely, these are individual features of the embryo.
The value of the coccyx-parietal size
An important indicator of the development of a little man at this stage of pregnancy is the size from the tailbone to the crown. If the woman had irregular menstruation, the duration of pregnancy is determined by this indicator. The rate of ultrasound screening for the first trimester of this indicator is from 3.3 to 7.3 cm for a period of ten to twelve weeks inclusive.
The thickness of the space of the neck area (TVP)
This indicator is also called the thickness of the neck fold. It is noticed that if the TBP of the embryo is thicker than 3 mm, then there is a risk of Down syndrome in a child. The values used by the doctor, shows the screening of the 1st trimester. Norms on ultrasound (thickness of the collar space) are considered very important for further observation of a pregnant woman.
Determining the location of the placenta
A baby place (placenta) is necessary for the intrauterine blood supply of a small person. It is necessary to provide it with food. Ultrasound provides an opportunity to determine the anomalies of the development and position of the placenta. If it is located too low relative to the bottom of the uterus, this is called placenta previa, which can lead to blocking the exit for the baby during labor.
Well show the location of the child site can ultrasound screening of 1 trimester. The rules of this study reject low placenta previa. But even if it is located close to the bottom of the uterus, doctors are not in a hurry to sound the alarm, since with the course of pregnancy it can rise. But if the position of the placenta has not changed in the later periods, the following problems are possible:
- the placenta can obscure the cervix and prevent natural childbirth;
- since in the second trimester the lower part of the uterus is stretched, the placenta can detach from it and cause severe bleeding (placental detachment).
Yolk sac examination
On the 15th-16th day of pregnancy from the day of conception, the process of formation of the yolk sac is underway. This “temporary organ” of a baby is examined by ultrasound (screening for the first trimester). Terms and standards for ultrasound examination should show its presence and size. If it has an irregular shape, is enlarged or reduced, then perhaps the fetus has stopped.
The yolk sac is an appendage located on the ventral side of the embryo. It contains a supply of yolk, necessary for the normal development of the baby. Therefore, it is very important to check the rate of ultrasound screening of the first trimester in comparison with the parameters of the study to monitor the progress of pregnancy. Indeed, at first (until the child’s organs function independently) this appendage performs the function of the liver, spleen, and is also used as a supplier of primary germ cells, actively participating in the formation of immunity and in metabolic processes.
The role of biochemical analysis of blood
Investigating the condition of the embryo, the doctor looks not only at the results of ultrasound (screening of the first trimester). The norms in it are as important as in the blood test. Such an analysis, in addition to an ultrasound examination, is carried out to determine at what level the specific proteins (placental) are located. The first screening is done in the form of a double test - to identify the level of 2 protein types:
If the levels of these proteins are altered, this indicates the possible presence of various chromosomal and non-chromosomal abnormalities. But identifying an increased risk does not mean that something is wrong with the embryo. Such results of screening 1 trimester, transcript, the rate of ultrasound indicate that you need to more closely monitor the course of pregnancy. Often, repeated research does not show the risk of genetic diseases.