Coccyx parietal size of the fetus by week of pregnancy. What kind of indicator? What deviations in CTE indicators may indicate

The coccyx-parietal size (CPR) is the greatest distance from the coccyx to the central point of the head (crone) of the fetus. This indicator allows you to very accurately, with an error of 1 to 4 days, determine the gestational age and date of birth. With an irregular cycle, this method will be more correct than determining the timing of pregnancy by ovulation, and with regular periods, the obtained values are usually simply compared with the obstetric period.

How shorter term pregnancy, the more informative this indicator is. The embryo still has practically no limbs, but only a heart and body. Therefore, the size of the fetus allows us to assess its condition and monitor its development over time.

By measuring and tracking sizes over several weeks (dynamic study), it is possible to identify abnormalities in the baby’s development over time. early stages. Doctors monitor CTE from 7 to 11 (less often 14) weeks of pregnancy, after which they use other values to monitor the baby - fetal fetometry. The ideal time to determine CTE is 11 weeks. It is usually prescribed at this time.

How is the size of the fetus measured?

To determine the coccyx-parietal size, ultrasound is used. The doctor scans the fetus, conditionally dividing the body into two symmetrical halves, and measures the length of the fetus from the crown to the tailbone several times. After this, select the maximum of the resulting sizes. If the baby moves during scanning, CTE is measured at the moment of its greatest extension.

Preparing for the examination is simple - you need to do it on an empty stomach and drink 1 liter of water an hour before the ultrasound.

The obtained values are compared with the tabulated values of fetal CTE by week of pregnancy.

As pregnancy progresses, the size of the fetus constantly increases, which allows us to conclude to some extent that the pregnancy is going well and the baby is also fine. The table shows normal CTE values: minimum (5th percentile column), average (50th percentile column) and maximum (95th percentile).

If more accurate measurements are needed, tracking the size of the fetus over time, tables for weeks and days of pregnancy are used.

It should be noted that all interpretation of the results must be carried out with a doctor. This will save you from wrong conclusions and unnecessary worries. Minor deviations from the norm may not mean the presence of abnormalities in the child. Since the fetus increases in growth every day, the tables are designed for each day of pregnancy from 7 to 14 weeks. But at the same time, a deviation in the size of the baby is allowed, corresponding to 4 days. In the second trimester, the measured CTE often does not correspond to the average value. From the 16th week, the coccygeal-parietal size of the fetus is not taken into account during examinations.

Fetal development at 11-12 weeks of pregnancy

First routine examination An ultrasound is usually prescribed at 11-13 weeks. The first trimester is already over and begins new stage baby development. At this time, the fetus’s hormonal system begins to actively work and brain function improves. The internal organs are also preparing with all their might - the intestines begin to contract, and the kidneys fill with urine. The structure of the skeleton changes - cartilage replaces bone. At week 12, the embryo’s webbed fingers disappear, and a week later he tries to move and bend his hands for the first time. At the end of the twelfth week of pregnancy, the average size of the fetus is 5.3 mm. Further, the baby’s growth rate will increase - in a couple of weeks he will grow by 2 mm instead of 1 mm daily.

The opinion of some gynecologists about the advisability of conducting the first ultrasound examination at 11 weeks is gaining popularity. It is during this period that some severe malformations of the embryo are best diagnosed. Also, at 11 weeks you can most accurately determine the period of conception and, accordingly, calculate the expected date of birth. Usually, the gynecologist keeps track of both periods - obstetric, calculated from the last menstruation, and the period that was established according to the CTE.

CTE is more or less than normal

An increase in the size of the fetus indicates the dynamic development of the baby in the womb. But it happens that the fetal CTE increases rapidly and is elevated for 1 week or more. This is not a reason to panic - you may just have a large baby. In this case, of course, it is worth paying attention to this and discussing the results of the study with your doctor. You do not need to be treated with drugs that stimulate accelerated metabolism. These include multivitamins and, for example, Actovegin. Perhaps the doctor will also review your diet and ask you to give up too many high-calorie and low-calorie foods. healthy products. It is also necessary to exclude anatomical defects and diabetes in the fetus. All these manifestations can affect the size of the baby.

It happens that the size of the fetus decreases at 11-13 weeks. At the same time, the tabulated norms of fetal CTE by week are not met. There may be several reasons:

Incorrectly determined obstetric gestational age. Perhaps your ovulation was much later than the middle of the cycle. In this case, the CTE at 11-13 weeks will differ from the expected obstetric period. In such cases, a repeat study is prescribed after 7-10 days. Based on the results of two measurements, a conclusion is made about the true gestational age.

Lack of hormones. Most often this is a lack of progesterone, which plays a very important role throughout the entire 40 weeks of pregnancy, and especially in. The danger of this kind of deficiency is a possible termination of pregnancy. The doctor usually prescribes appropriate medications that contain progesterone (, etc.)

, fetal death. If motor activity and cardiac activity are not observed, this is a signal for an urgent visit to your gynecologist. Timely consultation and medical intervention can save the life or reproductive function of a pregnant woman.

Infectious diseases. They also influence the development and size of the baby. They are identified using special tests, after which targeted therapy is carried out.

Diseases internal organs moms. These include heart and thyroid diseases.

Disorders of the uterine lining. In this case, the fetus is not able to attach to the wall of the uterus and develop normally. This is often followed by spontaneous abortion.

Genetic disorders of the fetus. To determine this type of disease in the first trimester, along with ultrasound, a biochemical test is performed. So, fetal CTE is an indirect, but very important indicator of the baby’s development in the first trimester. Timely completion of planned examinations and consultation with a gynecologist will help fill your pregnancy with pleasant expectations and worries and minimize worries.

Content

Ultrasonography is important throughout the entire period of bearing a child. After the first scan, a lot of new and incomprehensible information becomes available to future parents. CTE is one of the ultrasound parameters that accurately determines the gestational age. Also using this value you can identify possible deviations in fetal development.

Definition of the concept

The coccygeal-parietal size (CPS) is one of the main indicators that allows you to monitor the correct development of the embryo until the 14th week of pregnancy. CTE is determined during an ultrasound examination. The concept denotes the distance from the highest point of the crown to the lower border of the coccyx of the fetus.

Using this value, the doctor estimates the baby’s weight, gestational age, and correlates the information received with the standards indicated in the table. After the 14th week of gestation, determining the CTE is problematic, since the fetus becomes larger and the ultrasound sensor cannot cover this segment. Therefore, growth and development begin to be judged by the size of individual parts of the baby’s body.

Coccyx-parietal size can be measured after a month from conception.

CTE is measured in the first weeks of gestation, during this period it is the only coefficient that evaluates the course of pregnancy. The growth rate of the indicator and compliance with the standards in the table inform the doctor about the development of the fetus. Information about the baby’s heartbeat is also important, which can be recorded on an ultrasound starting from 5-6 weeks of pregnancy.

Measurement methods

CTE is determined during the first ultrasound performed at 12 weeks of pregnancy. IN ultrasound scanning The main planes are distinguished: sagittal, axial, coronal. The coccygeal-parietal size is measured by sagittal scanning in the position of full extension of the embryo's head.

The doctor must wait until the fetus has fully expanded. At this second, the specialist takes a freeze frame. Then, along the segment laid from the crown to the tailbone, the initial value is estimated. The value is correlated with the standards indicated in the tables. The resulting size determines exact date pregnancy, because many women have an irregular cycle or do not remember the first day of their last period.

KTR establishes the exact duration of pregnancy, the date of birth and allows you to identify possible anomalies in the development of the fetus. There are cases when ovulation occurs later than a woman expects or the attachment of the egg is slightly delayed. In such situations, the actual age of the embryo turns out to be less, which is what CTE reveals.

Table of norms

In the first weeks of pregnancy, all embryos grow at the same rate. Genetic differences that affect body parameters begin to appear a little later. The coccygeal-parietal size does not depend on nationality, environmental conditions and geographic latitude. That's why they installed general norms CTE by week of pregnancy in the table.

In the first weeks of pregnancy, there are even no fluctuations in values. Possible errors are allowed as the fetus grows. If the ultrasound machine was manufactured recently, then the values in the ultrasound protocol will be accurate, with tenths; if not, then the numbers will be integers.

Options for deviations from normal values

Non-compliance of KTE with the standards established in the tables is often recorded. The deviation can be either smaller or larger. Deterioration from the norm can be physiological or pathological.

An increase in the coccygeal-parietal size occurs for the following reasons:

diabetes mellitus in pregnancy;
Rhesus conflict;
large fruit;
doubts about the timing of the last menstruation.

To confirm that the values are exceeded, the woman must undergo an ultrasound again after 10 days.

The following factors cause a decrease in CTE:

frozen pregnancy;
insufficient hormonal synthesis;
delayed fertilization;
genetic diseases;
infectious diseases.

Even a slight deviation of the values from the norm in the table requires additional examination to determine the true cause of the problem.

Causes

Often, the deviation of CTE from normal values is explained by incorrect calculation of the gestational age. The doctor will correct such a mistake by correctly determining the onset of conception. But often serious disorders are diagnosed that affect the further course of pregnancy.

One of the reasons for delayed embryonic growth is placental insufficiency.

A too short coccygeal-parietal size can be caused by a woman’s poor lifestyle. If a pregnant woman smokes and drinks alcohol, the embryo develops in unhealthy conditions, which leads to a delay in its growth.

Non-developing pregnancy

The death of the embryo may be the reason for the lag of the coccygeal-parietal size from the norms in the tables. If the fetus has stopped developing and a miscarriage has not occurred, then the CTE will correspond to the values at the time of death.

In the first weeks, when it is impossible to determine the baby's heartbeat, a repeat scan is performed a few days later to confirm fetal death. In such cases, curettage of the uterine cavity is performed or drug interruption pregnancy. During obstetric curettage, embryonic cells are collected for genetic testing. This is necessary to establish the reasons for the death of the embryo.

Late ovulation and fertilization

A strong deviation of the CTE from the norm in the table may indicate an incorrect date or delayed ovulation. If implantation of the fertilized egg is delayed, the values will be less than normal.

To confirm this version, it is necessary to do a second screening, which is prescribed a week after the first. If there is an error in the calculation, the KTE will increase according to the actual week of pregnancy. Further medical monitoring will be carried out based on new data.

Hormonal imbalance

If the embryo develops, but there is a significant deviation of the CTE from the norm in the table, then the cause of this discrepancy may be a problem with hormones. With progesterone deficiency in female body Fetal growth slows down in the first weeks of pregnancy.

After examining the biological material of the expectant mother and confirming the diagnosis, hormonal therapy will be prescribed. Drug treatment restores hormone levels, which helps normalize the coccygeal-parietal size.

Infectious and genetic diseases

The presence of an infectious agent negatively affects the formation of the embryo. Pathogens cause a discrepancy between the actual CTE and the standards in the tables. Therefore, pregnant women need to be examined by passing the required tests. The doctor will prescribe a therapeutic regimen based on the results obtained.

Usually in the presence of pathological abnormalities at the genetic level, pregnancy spontaneously terminates in the first weeks.

Another reason for the slowdown in growth is chromosomal diseases: Patau, Down, Edwards syndrome. To accurately identify pathologies, it is necessary to undergo additional biochemical studies and submit DNA markers.

Pathologies of the uterus

Diseases of the reproductive organ affect the non-compliance of the CTE with the standards established in the tables. The following pathological conditions of the uterus lead to changes in values:

fibroids, in which ovum cannot fully develop;
endometrial insufficiency, developing as a result of miscarriages, abortions;
cervical erosion;
ectropion - inversion of the cervix into the vaginal area, which increases the risk of miscarriage.

Anomalies in the development of a woman’s internal organs also change indicators, so such patients are carefully examined to prevent all kinds of risks in a timely manner.

Additional examination

If the coccygeal-parietal size does not correspond to the standards in the table, a repeat ultrasound will be required. In addition to scanning, expectant mothers are offered:

amniocentesis - sampling amniotic fluid using a puncture;
cordocentesis - blood sampling from the umbilical cord;
chorionic villus biopsy- a method for detecting congenital anomalies from cells taken from tissues not affecting the placenta.

Since the described diagnostic methods are invasive, they require written agreement future mother.

There is also a non-invasive option - a prenatal DNA test, which requires the woman's venous blood. The baby's red blood cells are identified in the mother's biological material, from which the baby's DNA is isolated, and the likelihood of developmental defects is determined. A similar study is carried out from the 8th week of pregnancy.

Fetal CTE is an important indicator that allows you to determine the exact duration of pregnancy and identify possible pathologies. If the indicator does not correspond to the norm in the table, additional examinations are required.

Twelve weeks of pregnancy - significant date for a woman, since this is the end of the first trimester. During this period, the placenta produces enough progesterone, and with the extinction of hormonal function, the corpus luteum gradually decreases. At this time, screening is carried out in the first trimester (from 11 to 13 weeks and 6 days), to identify groups at risk of chromosomal abnormalities, as well as. An ultrasound examination at 12 weeks of pregnancy shows fetal development very accurately, especially the term indicator.

An important measurement that is of paramount importance is the fetal calcification factor at 12 weeks. This indicator is used to determine the size of the fetus and calculate the duration of pregnancy in conjunction with the approximate weight. The coccygeal-parietal size at 12 weeks is about 5.3 cm. If it passed without complications and it grew by 1 mm per day, then the human embryo at 12 weeks accelerates its growth rate to 1.5-2 mm per day. Doctors recommend measuring fetal CTE at 11 or 12 weeks.

It should be taken into account that the size of the coccygeal-parietal size depends on the duration of pregnancy to the nearest day, so the normal error is three to four days. The normal average CTE of an embryo is 51 mm. If there is a slight deviation, do not worry - normal fluctuations from 42 to 59 mm are possible.

For comparison, let’s indicate the fetal calf temperature at 11 weeks: normal indicator is 42 mm, normal permissible deviations are 34-50 mm. When comparing these indicators, you can see how important every day is for performing an ultrasound.

Expectant mothers are of course interested in what a fetus looks like and what it can do at 12 weeks. During an ultrasound, a mother can see her baby sucking his thumb and hear the little heart beating 110-160 beats per minute. The baby actively moves and turns over in the amniotic sac, the chest falls and rises while breathing. Also, the fetus already has the ability to close its eyes, open its mouth and move its fingers.

As for development indicators, it is worth noting the maturation of the thymus gland, which is responsible for the body’s production of lymphocytes and the development of immunity. The pituitary gland begins to produce hormones that affect the growth of the fetus, the body's metabolism and the reproductive function of the body. The fetal liver begins to produce bile, which will help in digesting food. Digestive system ready to digest glucose.

A 12-week embryo weighs about 9-13 grams, the fetus is elongated and is in a sitting position. The length from the crown to the sacrum is approximately 70-90 mm. By this time, the heart of the embryo has four chambers: two atria and two ventricles, and the contraction frequency varies from 150 to 160 beats per minute. The bony palate begins to form, the rudiments of baby teeth begin to form, and the vocal cords form in the larynx.

This period of development is especially important for boys. In progress active action testosterone, which is produced by the gonads of boys, begins the formation of the external genitalia - the penis and scrotum. If this function is impaired, hermaphroditism may occur.

How does a mother feel at 12 weeks of pregnancy?

With the normal course of pregnancy and fetal development, a pregnant woman should gain from 1.8 to 3.6 kg. The rate of weight gain is from 300 to 400 grams per week. When gaining weight more than normal it is necessary to reduce the amount of simple carbohydrates (sweets, cookies, halva, etc.).

Many women are concerned about the appearance of age spots on the face, neck, chest during this period, as well as the appearance of a dark line from the navel to the pubis. However, there is no need to worry, these are normal manifestations, and they will soon pass after childbirth.

An embryo at 12 weeks has successfully passed the embryonic path of life and after 12 weeks is called a fetus. In our article future mom will find a lot for himself useful information to learn more about your future baby.

The coccygeal-parietal size or CTE by week of pregnancy can only be measured at the first mandatory screening. This diagnostic indicator helps not only to determine the gestational age, but also provides an opportunity to judge the degree of development of the baby inside the womb.

What does fetal CTE mean on ultrasound during pregnancy?

CTE on ultrasound during pregnancy is the main parameter that determines the size and size of the embryo. Measurements are most reliable at the gestation stage from 10 to 16 weeks. Before this period, the fetus is still too small for such measurements; later, the diagnostic method is no longer so informative.

Understanding CTE during pregnancy makes it possible to determine the exact period of gestation. Thanks to the coccygeal-parietal size, doctors evaluate dynamic growth indicators, calculate the likelihood of forming a large fetus, and also compare the risks of intrauterine growth retardation.

At the ultrasound screening stage, specialists take longitudinal measurements, which do not include the limbs of the embryo. Triple measurements are often used, when during 1 study three measurements are taken during the period of maximum extension of the baby, but only the average sizes are taken into account.

The gestational age is determined according to certain rules:

index< 10 мм + 6;
> 10 mm + 6.5.

Thus, if the coccygeal-parietal size of the fetus is 25 mm, then add a value of 65, and the gestation period corresponds to the 9th obstetric week. To calculate by day, an index of 42 is used, and the size of the parameter under study should not exceed 84 mm. For example, embryo 8 mm + 42 = 50 days of gestation. The error in fetal CT by week of pregnancy ranges from 3 to 6 days.

KTR norm table by week of pregnancy

The size of the ctr increases over time over the weeks of pregnancy as the fetus grows and develops. If ultrasound is performed several times, the coccygeal-parietal length is studied according to its dynamic properties, which makes it possible to exclude various pathologies.

KTR norm table by week of pregnancy:

SRT, mm	Weeks + days	SRT, mm	Weeks + days	SRT, mm	Weeks + days
7	6+3	32	10	57	12+2
8	6+4	33	10+1	58	12+3
9	6+6	34	10+2	59	12+3
10	7	35	10+2	60	12+4
11	7+2	36	10+3	61	12+4
12	7+3	37	10+4	62	12+5
13	7+4	38	10+5	63	12+5
14	7+5	39	10+6	64	12+6
15	7+6	40	11	65	12+6
16	8	41	11	66	13
17	8+1	42	11+1	67	13
18	8+2	43	11+2	68	13+1
19	8+3	44	11+2	69	13+1
20	8+4	45	11+3	70	13+2
21	8+5	46	11+3	71	13+2
22	8+6	47	11+4	72	13+3
23	9	48	11+5	73	13+3
24	9+1	49	11+5	74	13+4
25	9+2	50	11+6	75	13+4
26	9+3	51	11+6	76	13+5
27	9+3	52	12	77	13+5
28	9+4	53	12+1	78	13+5
29	9+5	54	12+1	79	13+6
30	9+6	55	12+2	80	13+6
30	10	56	-	-	-

If the CTE norm is longer than the term, then this often indicates an early diagnosis of a large fetus. In this case, doctors recommend adhering to certain dietary rules and not abusing medications and multivitamins.

Deviations of CTE downward

Most often, with significantly reduced indicators, an incorrectly calculated obstetric gestation period is provided. The ovulation period and fertilization of the egg, in this case, occurred later. To double-check the data, a repeat ultrasound examination is scheduled after about a week.

Other deviations include:

pregnancy that has stopped developing, when the embryo dies inside the womb due to certain pathological processes. Diagnosis is made by the absence of heartbeats and motor activity. The situation requires immediate surgical intervention so as not to provoke complications.
insufficient production of progesterone or other hormones can result in miscarriage. An additional ultrasound examination and drug therapy are prescribed to normalize hormonal levels.
Availability infectious diseases is also caused by impaired growth and formation of the child. Additional tests are carried out and treatment of the infection is provided.
suspicion of genetic disorders associated with various syndromes is confirmed by analyzing 3 markers - screening, hCG and protein-A.

KTR norms by week of pregnancy are one of the main indicators of the first screening; the study helps to assess the degree of formation of the fetus inside the womb and take the necessary medical actions to improve the pathological situation if abnormalities are diagnosed.

CTP (coccygeal-parietal size) can be determined with a sagittal scan by measuring the distance from the crown of the fetus to the coccyx. This technique allows you to find out with maximum accuracy the age of the embryo and its size. Based on this data, the physician can judge the growth and formation of the fetus, and also help to avoid any abnormalities.

CTE of the embryo in the early stages

In order for the CTE results to be as accurate as possible, a photograph of the fetus must be taken at a time when it is in a more extended state. The distance is measured from the highest point of the crown to the tailbone. It is believed that CTE is the most accurate indicator that determines the duration of pregnancy, since it does not depend on race, individual characteristics and the gender of the child.

If the coccygeal-parietal size does not correspond slightly to the required norm, there is no need to worry: these results are compared with the CTE table by week of pregnancy, but it is impossible to accurately predict the development of the child based only on these data. Each fruit has its own physiological characteristics. However, if the CTE increases over a period of several weeks, then there is a possibility of having a baby weighing 4 or even 6 kg.

Despite the fact that the readings of the fetal CTE and the table do not always coincide, it is still worth taking its values into account. The reasons for high CTE may be:

the mother has diabetes mellitus;
obesity in a pregnant woman;
use of drugs that promote metabolism;
taking various vitamin complexes.

The larger size of the embryo is also a signal that the expectant mother should limit herself from excessive consumption of foods that increase cholesterol. A more severe case is the occurrence of neoplasms, that is, the presence of birth defects.

Consequences of abnormal fetal development

In most cases the group medicines provokes fetal growth, and up to critical parameters. While still in the womb, the baby can weigh more than 5 kg. Taking into account the data from the CTE table by week, doctors can adjust the size of the fetus at an early stage of pregnancy.

If the CTE is much lower than the table value, then in most cases the cause may be more late date fertilization of the egg. In order to confirm the absence of any pathologies, doctors prescribe an ultrasound.

Otherwise, the woman’s body, and itself unborn child, may suffer greatly. Having established the cause and form of the deviation, specialists can provide timely assistance and correct the development of the embryo.

In the womb, the baby grows and increases in size: every day by 1 or 2 mm. And this will help make forecasts of the fetal CTE table readings by week and day, determining the rate of deviation, which should not exceed 3 days. Therefore, from the 7th week of pregnancy until the 15th week, the table is the main indicator of the child’s growth. At the 16th week, the life and development of the fetus is monitored by doctors using ultrasound.

At 7 weeks of pregnancy maximum size from head to tailbone should not exceed 11 mm, and the average value at the 8th week is 14 mm. At the 11th week, the average CTE value is ideally 41 mm, and at the 13th week it is approximately 54−56 mm, not more than 71 mm. The maximum value (95 percentile) at the 14th week of pregnancy should not exceed 86 mm.

Since the CTE value is measured in millimeters, you do not need a calculator to calculate it yourself. In the womb, the child should grow and develop moderately, in accordance with established standards.