Ultrasound during pregnancy: interpretation.

Introduction

Accurate knowledge of the gestational age is important for assessing the nature of fetal development, diagnosing certain congenital defects, choosing the optimal timing of termination of pregnancy and setting the date for issuing prenatal leave (especially in women with irregular menstrual cycles), as well as for conducting scientific research. Determining the weight and height of the fetus is important in the prevention of prematurity, post-term pregnancy, choosing the optimal method of delivery in the presence of a large fetus, diagnosing its malnutrition and developmental anomalies.

This work presents for the first time statistical data obtained from the examined group of women whose gestational age was verified based on in vitro fertilization (IVF) data. In this case, the results obtained are compared with data calculated using the equations of the most famous foreign authors, which are used in most.

The purpose of this work is to assess the possibility of the standards we have established for individual parameters of fetometry and the fetometry created on their basis. computer program to calculate the gestational age, weight and growth of the fetus in the 1st, 2nd and 3rd trimesters during a physiologically developing pregnancy.

Materials and methods

An ultrasound examination was performed on 155 women with in vitro fertilization (first group), of which 40 women were in the first trimester of pregnancy, 64 in the second and 51 in the third trimester. This group was used to verify the exact gestational age. The second group included 61 women who were referred for termination of pregnancy at 14-26 weeks for social reasons. The average weight of the fetus was 426±35.4 g, height - 26.2±1.4 cm. This group of patients was used to verify the weight and growth of the fetus in the second trimester of pregnancy. To determine fetal weight in the third trimester, 101 women with a physiological pregnancy were examined at 37-41 weeks of gestation.

The weight of children at birth ranged from 2253 to 4900 g, averaging 3530 ± 512 g. The height of children varied from 46 to 58 cm and averaged 51.6 ± 1.4 cm. The condition of children weighing less than 3000 g was assessed as normal, and therefore the presence of a healthy low-weight fetus was stated.

When performing fetometry, we measured the coccygeal-parietal size of the embryo (in the first trimester), biparietal size and fronto-occipital size of the fetal head, average abdominal diameter (F), length of the femur (DF), tibia (TI) and humerus (HB), foot length (St), average diameter of the fetal heart (C), interhemispheric size of the cerebellum (IHR), average size of the fetal head (D). The coccygeal-parietal size of the embryo was measured by scanning it longitudinally from the parietal bone to the coccyx with the head of the embryo in a bent position (Fig. 1).

Rice. 1.

The biparietal size was measured by visualizing the M-echo at the level of the third ventricle of the brain, at the same distance from the parietal bones, while obtaining an image of the cavity of the septum pellucidum and the quadrigemone. The measurement was made from the outer to the inner contour of the parietal bones. The fronto-occipital size was determined between the most distant points of the outer contours of the frontal and occipital bones of the fetal skull.

The average size of the fetal head was calculated as the arithmetic mean of the biparietal and fronto-occipital sizes (Fig. 2).

Rice. 2.

The average heart diameter was taken to be the arithmetic mean of its two maximum mutually perpendicular dimensions, measured in diastole during transverse scanning at the level of the leaflet valves (Fig. 3). The thickness of the heart was measured to the inner surfaces of the pericardium and the width - from the inner surface (endocardium) of the most distant part of the atrium to the end of the interventricular septum.

Rice. 3.

The average abdominal diameter was calculated as the arithmetic mean between the transverse and anteroposterior diameters (Fig. 4). Measurements were taken at the level of the umbilical vein.

Rice. 4.

MRM was determined by horizontal scanning of the fetal head at the level of the fourth ventricle of the brain according to the maximum distance between the extreme lateral boundaries of the opposite hemispheres (Fig. 5). If visualization of the entire cerebellum was not clear enough, its hemisphere was measured. It was defined as the distance between the extreme lateral surface of the hemisphere and the middle of the cerebellar vermis. Then the resulting value was doubled. In cases where the lateral surface of the cerebellum was not clearly defined, its measurement was made from the medial surface of the echo-negative subarachnoid space of the lateral parts of the posterior cranial fossa.

Rice. 5.

The calcified part of their diaphysis was taken as the length of the femur, tibia and humerus (Fig. 6a, b). Foot length was determined as the distance between the distal phalanx thumb and heel bone.

Rice. 6.

The calculation of fetometry data (gestational age, weight and growth of the fetus) was carried out on a personal computer using a program we developed for these purposes, and equations were derived that simultaneously included several biometric parameters of the fetus. For a comparative assessment of the results obtained, we used programs built into the ultrasonic device for calculating similar parameters according to the most famous authors - J.C. Birnholz, S. Campbell, F.P. Hadlock, M. Hansmann and J.C. Hobbins.

Research results

This work provides regulatory tables for determining the correspondence of individual parameters of fetal biometry to the gestational age (Table 1-11). At the same time, analysis of fetometry data in the first trimester (Table 12) showed that the equation we obtained for determining the duration of pregnancy gives slightly better results. Thus, the average error, according to our data, was 2.2 days, while according to other authors it varied from 3.2 to 4.2 days.

Table 1. Coccyx-parietal size of the embryo, cm.

Gestational age	Coccyx-parietal size	Gestational age	Coccyx-parietal size	Gestational age	Coccyx-parietal size
2 weeks	0,3	8 weeks	2,7	11 weeks	6
3 weeks, 2 days	0,4	8 weeks, 1 day	2,9	11 weeks, 1 day	6,1
4 weeks, 3 days	0,5	8 weeks, 2 days	3	11 weeks, 2 days	6,3
4 weeks, 4 days	0,6	8 weeks, 3 days	3,1	11 weeks, 3 days	6,5
4 weeks, 5 days	0,7	8 weeks, 4 days	3,3	11 weeks, 4 days	6,7
4 weeks, 6 days	0,8	8 weeks, 5 days	3,4	11 weeks, 5 days	6,9
5 weeks	0,9	8 weeks, 6 days	3,5	11 weeks, 6 days	7,1
5 weeks, 2 days	1	9 weeks	3,6	12 weeks	7,3
5 weeks, 3 days	1,1	9 weeks, 1 day	3,8	12 weeks, 1 day	7,5
5 weeks, 5 days	1,2	9 weeks, 2 days	3,9	12 weeks, 2 days	7,7
5 weeks, 6 days	1,3	9 weeks, 3 days	4,1	12 weeks, 3 days	7,9
6 weeks, 1 day	1,4	9 weeks, 4 days	4,2	12 weeks, 4 days	8,1
6 weeks, 2 days	1,5	9 weeks, 5 days	4,4	12 weeks, 5 days	8,3
6 weeks, 3 days	1,6	9 weeks, 6 days	4,5	12 weeks, 6 days	8,5
6 weeks, 4 days	1,7	10 weeks	4,7	13 weeks	8,6
6 weeks, 5 days	1,8	10 weeks, 1 day	4,9	-	-
6 weeks, 6 days	1,9	10 weeks, 2 days	5,1	-	-
7 weeks	2	10 weeks, 3 days	5,2	-	-
7 weeks, 1 day	2,1	10 weeks, 4 days	5,3	-	-
7 weeks, 2 days	2,2	10 weeks, 5 days	5,5	-	-
7 weeks, 3 days	2,3	10 weeks, 6 days	5,8	-	-
7 weeks, 4 days	2,4	-	-	-	-
7 weeks, 5 days	2,5	-	-	-	-
7 weeks, 6 days	2,6	-	-	-	-

The tables below show the percentile curves (95, 50, 5)- this is a special method of statistical processing of medical data (in other words, the sum of % is not equal to 100 is normal) - approx. layout designer

table 2. Biparietal size of the fetal head (BF), see.

Gestational age, weeks	95%	50%	5%
14	2,6	2,2	1,8
15	3,2	2,7	2,2
16	3,7	3,2	2,6
17	4,3	3,6	2,9
18	4,8	4	3,2
19	5,2	4,4	3,6
20	5,6	4,7	3,9
21	5,9	5	4,2
22	6,3	5,4	4,5
23	6,6	5,7	4,8
24	6,8	5,9	5,1
25	7,1	6,2	5,3
26	7,4	6,5	5,6
27	7,6	6,7	5,9
28	7,8	7	6,2
29	8,1	7,2	6,4
30	8,3	7,5	6,7
31	8,5	7,7	6,9
32	8,7	7,9	7,2
33	8,9	8,1	7,4
34	9,1	8,3	7,6
35	9,3	8,6	7,9
36	9,4	8,8	8,1
37	9,6	9	8,3
38	9,8	9,2	8,6
39	10	9,3	8,8
40	10,1	9,5	9
41	10,3	9,7	9,2

Table 3. Fronto-occipital size of the fetal head (FHR), see.

Gestational age, weeks	95%	50%	5%
14	3,3	2,5	1,7
15	3,9	3,2	2,5
16	4,9	4,1	3,2
17	5,8	4,8	3,8
18	6,4	5,4	4,3
19	7	5,9	4,8
20	7,5	6,4	5,3
21	7,9	6,8	5,7
22	8,3	7,2	6,1
23	8,7	7,6	6,5
24	9	7,9	6,9
25	9,3	8,3	7,2
26	9,6	8,6	7,5
27	9,9	8,9	7,9
28	10,2	9,2	8,2
29	10,5	9,5	8,5
30	10,8	9,8	8,8
31	11	10	9
32	11,3	10,3	9,3
33	11,5	10,5	9,6
34	11,7	10,8	9,9
35	12	11	10,1
36	12,2	11,3	10,4
37	12,4	11,5	10,6
38	12,6	11,7	10,9
39	12,8	11,9	11,1
40	13	12,2	11,3
41	13,2	12,4	11,6

Table 4. Average size of the fetal head (D), cm.

Gestational age, weeks	95%	50%	5%
14	2,5	2,2	1,9
15	3,4	3	2,4
16	4,3	3,7	2,9
17	5	4,2	3,4
18	5,5	4,7	3,8
19	6	5,1	4,2
20	6,4	5,5	4,6
21	6,8	5,9	5
22	7,2	6,3	5,3
23	7,5	6,6	5,6
24	7,8	6,9	6
25	8,1	7,2	6,3
26	8,4	7,5	6,6
27	8,7	7,8	6,9
28	9	8,1	7,2
29	9,2	8,3	7,4
30	9,5	8,6	7,7
31	9,7	8,8	8
32	9,9	9	8,2
33	10,2	9,3	8,5
34	10,4	9,6	8,7
35	10,6	9,8	9
36	10,8	10	9,2
37	11	10,2	9,5
38	11,2	10,4	9,7
39	11,4	10,6	9,9
40	11,6	10,8	10,1
41	11,8	11	10,3

Table 5. Interhemispheric size of the cerebellum (IMD), cm.

Gestational age, weeks	95%	50%	5%
14	1,4	1,2	1
15	1,5	1,3	1,1
16	1,6	1,4	1,2
17	1,8	1,6	1,4
18	1,9	1,7	1,5
19	2	1,8	1,6
20	2,2	2	1,8
21	2,3	2,1	1,9
22	2,6	2,3	2
23	2,7	2,4	2,1
24	2,9	2,6	2,3
25	3	2,7	2,4
26	3,2	2,9	2,6
27	3,3	3	2,7
28	3,5	3,2	2,9
29	3,6	3,3	3
30	3,8	3,5	3,2
31	3,9	3,6	3,3
32	4,1	3,8	3,5
33	4,3	4	3,7
34	4,5	4,2	3,9
35	4,7	4,4	4,1
36	4,9	4,6	4,3
37	5,2	4,8	4,4
38	5,4	5	4,6
39	5,6	5,2	4,8
40	5,9	5,5	5,1
41	6,1	5,7	5,3

Table 6. Average fetal heart diameter (C), cm.

Gestational age, weeks	95%	50%	5%
14	1,5	1,2	1
15	1,6	1,3	1,1
16	1,7	1,5	1,2
17	1,9	1,6	1,3
18	2	1,7	1,5
19	2,1	1,8	1,5
20	2,2	1,9	1,6
21	2,4	2	1,7
22	2,5	2,1	1,8
23	2,6	2,2	1,9
24	2,7	2,4	2
25	2,8	2,5	2,1
26	2,9	2,6	2,2
27	3	2,7	2,3
28	3,2	2,8	2,4
29	3,3	2,9	2,6
30	3,4	3	2,7
31	3,5	3,1	2,8
32	3,6	3,3	2,9
33	3,7	3,4	3
34	3,8	3,5	3,1
35	3,9	3,6	3,2
36	4	3,7	3,4
37	4,1	3,8	3,5
38	4,2	3,9	3,6
39	4,3	4	3,7
40	4,5	4,1	3,8
41	4,6	4,3	4
42	4,7	4,4	4,1

Table 7. Average abdominal diameter (F), cm.

Gestational age, weeks	95%	50%	5%
14	3,2	2,5	1,8
15	3,6	2,9	2,1
16	4	3,3	2,5
17	4,5	3,6	2,8
18	4,9	4	3,1
19	5,3	4,4	3,5
20	5,6	4,7	3,8
21	6	5,1	4,1
22	6,4	5,4	4,4
23	6,7	5,7	4,7
24	7,1	6,1	5
25	7,4	6,4	5,3
26	7,8	6,7	5,6
27	8,1	7	5,9
28	8,5	7,4	6,2
29	8,8	7,7	6,5
30	9,1	8	6,8
31	9,4	8,3	7,1
32	9,7	8,6	7,4
33	10	8,9	7,7
34	10,3	9,2	8
35	10,6	9,5	8,3
36	10,9	9,8	8,5
37	11,2	10	8,8
38	11,5	10,3	7,1
39	11,8	10,6	9,4
40	12,1	10,9	9,7
41	12,3	11,2	9,9
42	12,6	11,4	10,2

Table 8. Fetal humerus length (HF), cm.

Gestational age, weeks	95%	50%	5%
14	1,5	1,1	0,7
15	1,9	1,5	1
16	2,3	1,8	1,3
17	2,7	2,2	1,6
18	3,1	2,5	1,9
19	3,4	2,7	2,1
20	3,6	3	2,4
21	3,9	3,2	2,6
22	4,1	3,5	2,8
23	4,3	3,7	3
24	4,6	3,9	3,3
25	4,8	4,1	3,5
26	4,9	4,3	3,7
27	5,1	4,5	3,8
28	5,3	4,7	4
29	5,5	4,8	4,2
30	5,6	5	4,4
31	5,8	5,2	4,6
32	6	5,4	4,7
33	6,1	5,5	4,9
34	6,3	5,7	5,1
35	6,4	5,8	5,2
36	6,5	6	5,4
37	6,7	6,1	5,5
38	6,8	6,3	5,7
39	7	6,4	5,9
40	7,1	6,5	6
41	7,2	6,7	6,1
42	7,3	6,8	6,3

Table 9. Fetal femur length (DF), cm.

Gestational age, weeks	95%	50%	5%
14	1,4	1,1	0,8
15	1,8	1,5	1
16	2,3	1,8	1,3
17	2,8	2,2	1,6
18	3,2	2,5	1,8
19	3,5	2,8	2,1
20	3,8	3,1	2,3
21	4,2	3,4	2,6
22	4,4	3,6	2,8
23	4,7	3,9	3,1
24	5	4,1	3,3
25	5,2	4,4	3,6
26	5,5	4,6	3,8
27	5,7	4,9	4
28	5,9	5,1	4,3
29	6,1	5,3	4,5
30	6,3	5,6	4,7
31	6,6	5,8	5
32	6,8	6	5,2
33	6,9	6,2	5,4
34	7,1	6,4	5,7
35	7,3	6,6	5,9
36	7,5	6,8	6,1
37	7,7	7	6,3
38	7,8	7,2	6,5
39	8	7,4	6,8
40	8,2	7,6	7
41	8,3	7,7	7,2
42	8,5	7,9	7,4

Table 10. Length of the fetal tibia (BB), cm.

Gestational age, weeks	95%	50%	5%
14	1,1	0,8	0,4
15	1,7	1,2	0,7
16	2,1	1,6	1,1
17	2,5	1,9	1,4
18	2,8	2,2	1,6
19	3,1	2,5	1,9
20	3,4	2,8	2,1
21	3,6	3	2,4
22	3,9	3,2	2,6
23	4,1	3,5	2,8
24	4,3	3,7	3
25	4,5	3,9	3,2
26	4,7	4,1	3,4
27	4,9	4,3	3,6
28	5,1	4,5	3,8
29	5,3	4,7	4
30	5,5	4,8	4,2
31	5,6	5	4,3
32	5,8	5,2	4,5
33	6	5,3	5,7
34	6,1	5,5	4,8
35	6,3	5,6	5
36	6,4	5,8	5,1
37	6,6	5,9	5,3
38	6,7	6,1	5,5
39	6,9	6,2	5,6
40	7	6,4	5,7
41	7,1	6,5	5,9
42	7,3	6,6	6

Table 11. Foot length (St), cm.

Gestational age, weeks	95%	50%	5%
14	1,4	1,2	0,9
15	1,9	1,6	1,2
16	2,4	1,9	1,6
17	2,8	2,3	1,9
18	3,2	2,6	2,2
19	3,6	2,9	2,4
20	3,9	3,2	2,7
21	4,2	3,4	2,9
22	4,5	3,7	3,2
23	4,7	4	3,4
24	5	4,2	3,7
25	5,3	4,5	3,9
26	5,5	4,7	4,1
27	5,7	5	4,4
28	5,9	5,2	4,6
29	6,1	5,4	4,8
30	6,4	5,6	5,2
31	6,6	5,9	5,4
32	6,7	6,1	5,6
33	6,9	6,3	5,9
34	7,2	6,6	6,1
35	7,5	6,9	6,4
36	7,7	7,2	6,7
37	8	7,5	7
38	8,2	7,7	7,3
39	8,4	8	7,6
40	8,5	8,2	7,8
41	8,8	8,5	8,1
42	9,1	8,8	8,4

5 12,1 13,8 7 101-150 15,8 13 9,1 11,7 7 151-200 12,9 5 13,1 10,6 10 201-250 7,9 4 9,1 11,7 9 251-300 6 4 6,1 4,3 8 301-350 7,9 5 4 6,4 6 351-400 6,9 6 5,1 4,3 7 > 400 6 53 34,3 29,8 32

When calculating fetal weight in the second trimester of pregnancy (Table 14), according to various authors, it turned out that the calculated values ​​correspond to the actual ones only for J.C. Hobbins. The accuracy of determining fetal weight at these stages of pregnancy, according to our data, is quite high; the average error was 27.6±27.8 g (6.5% of its mass). Using the criteria of J.C. Hobbins it turned out to be significantly higher and averaged 60.3±55.8 (14.2% of fetal weight). At the same time, a minor error in determining the weight of the fetus, amounting to less than 20 g, occurred in 55.5% of cases in our observations, and when using the criteria of J.C. Hobbins - at 20.6%.

Currently, we have not encountered any reports indicating the possibility of ultrasound determination of fetal growth in the second trimester of pregnancy. The data we presented indicate that it is possible to determine fetal growth at these stages of pregnancy with fairly high accuracy. The use of our proposed computer fetometry showed that the average error in determining fetal growth was small and amounted to 0.76 ± 0.84 cm (2.9% of its height). A slight error in determining fetal growth, not exceeding 1 cm, was found in 81.3% of observations.

When determining the estimated value of fetal weight in the third trimester in the case of a physiological pregnancy, it was found that with computer fetometry the average error was equal to 175.5 ± 133 g, which amounted to 4.9% of its weight (see Table 5). The best result noted among other authors was found using the criteria of J.C. Birnholz - 279.6±199 g (7.9% of fruit weight) and F.P. Hadlock - 307.4±219.2 g (10% of fruit weight), while the least reliable - obtained using the equation proposed by S. Campbell - 446.5±288.2 g (12.6% of its weight) . A small error, less than 200 g in computer fetometry, was recorded in 65.3% of cases when using J.C. criteria. Birnholz - 43.5%, F.P. Hadlock - in 38% and S. Campbell - in 28% (Table 13).

It is important to note that when calculating the predicted fetal weight using the equations and tables of the above authors, the calculation was not always possible (in particular, this was observed when large fruits or pronounced asymmetry in the size of the abdomen and head or abdomen and thigh).

We did not find information about the possibility of determining fetal growth from any of these researchers. In our observations, the average error in determining fetal growth was 1.5±1.2 cm and amounted to 3.1% of its height. Moreover, in 80.2% of cases, the error in calculating height did not exceed 2 cm (Table 15).

Table 15. Distribution of the magnitude of error in determining fetal growth during full-term pregnancy, %.

Discussion

Analysis of the data obtained indicates a fairly high accuracy of our proposed computer fetometry for establishing the gestational age throughout pregnancy, as well as the weight and growth of the fetus in the second and third trimesters of pregnancy, compared to programs by other authors, which are currently widely used in modern ultrasound equipment .

The data obtained when calculating fetal weight in the second trimester showed that the accuracy of its determination in our observations was more than 2 times higher than when using the criteria proposed by J. Hobbins.

In the third trimester, the average error in determining the gestational age according to our data was 2 times less than that of F.P. Hadlock, who had the best result among other authors. The standard deviation in our observations also turned out to be significantly lower than that of other authors, which indicates greater reliability of the results obtained.

In the third trimester of pregnancy, the average error in determining fetal weight at birth was 1.6 times less than that of J.C. Birnholz, 1.75 times less than F.P. Hadlock, and 2.5 times less than S. Campbell.

Important advantages of computer fetometry should also include the absence of large deviations of calculated indicators from their actual values. Thus, the magnitude of the error in determining the gestational age exceeding 10 days when using computer fetometry was 3.6 times less common than when using the F.P. equations. Hadlock, 4.1 times less than according to J.C. Hobbins, 5 times less than according to M. Hansmann, and 5.4 times less than according to S. Campbell. A significant error in determining fetal weight exceeding 400 g was 4 times less common in our observations than when using J.C. criteria. Birnholz, 5.3 times less often than according to F.P. Hadlock, 5.7 times less often than according to J.C. Hobbins and M.J. Shepard and 8.8 times less often than according to S. Campbell (see Table 13). Quite accurate results, in our opinion, were also obtained when determining fetal growth (see Table 15).

Thus, the presented data indicate that ultrasound computer fetometry is a valuable method, the use of which allows one to determine with fairly high accuracy the term, weight and growth of the fetus throughout pregnancy, which is important for practical medicine.

Literature

1. Birnholz J.C. Estimated fetal weight. The principles and practice of ultrasonography in obstetrics and gynecology. ed. R.C. Sanders, A. E. James. Norwale, 1985, Appleton-Century-Croft`s, pp. 642-643.
2. Campbell S., Wilkin D. Ultrasonic measurement of fetal abdomen circumference in the estimation of fetal weight // Brit. J. Obstet. Gynaecol., 1975, Vol.82, pp. 689-794.
3. Hadlock F.R., Harrist R.E. et al. Sonographic estimation of fetal weight. - Radiology, 1984, 150:537.
4. Hansmann M., Hackeloer B.J., Staudach A. Ultrasound diagnosis in obstetrics and gynecology. - Berlin, Springer-Verlag, 1986, 495 p.
5. Hobbins J.C. In Book: Operation manual for ultrasound System for fetal growth measurement, 105p. Toshiba Corp., Amsterdam, 1992.

Ultrasound examination, or ultrasound is an examination method that is widely used during pregnancy at any stage. This diagnostic test is relatively simple, highly informative and safe for both mother and child. The main objectives of ultrasound during pregnancy are:

The following tables provide data on the biometric indicators of the fetus, which are measured at each. They are presented at the 10th, 50th and 95th percentiles. Most often they focus on the 50th percentile, and the rest are considered normal fluctuations.

Dimensions of the fetal head by week of pregnancy

Gestation period, weeks	Fronto-occipital size (LZR), mm			Biparietal size (BPR), mm

Abdominal and fetal head circumference

Gestation period, weeks	Abdominal circumference, mm			Head circumference, mm

Length of fetal femur and femur bones

Gestation period, weeks	Shin bones, mm			Femur, mm

Length of fetal humerus and forearm bones

Gestation period, weeks	Length of forearm bones, mm			Humerus length, mm

Norms at the first ultrasound at 10-14 weeks

The first screening ultrasound is performed at 10-14 weeks. Its main tasks are:

• Study of the thickness of the collar zone(area between soft tissues, covering the spine and the inner surface of the skin, filled with fluid). Assessing the size of the neck fold is very important because... is a fairly accurate way to timely diagnose various chromosomal diseases, in particular Down syndrome. If there is an enlarged nuchal space, the doctor should refer the pregnant woman for consultation with a geneticist. The woman is prescribed additional examination methods: a blood test for alpha-fetoprotein and human chorionic gonadotropin, invasive diagnostic methods (amniocentesis - study of amniotic fluid, placentocentesis - study of placental cells, cordocentesis - study of blood taken from the fetal umbilical cord).

Normal values ​​of the nuchal translucency (NVP) in the first trimester of pregnancy

Gestation period, weeks	Thickness of collar space, mm
	percentile	50th percentile	95th percentile
10 weeks 0 days - 10 weeks 6 days
11 weeks 0 days - 11 weeks 6 days
12 weeks 0 days – 12 weeks 6 days
13 weeks 0 days - 13 weeks 6 days

• Measuring the coccygeal-parietal size (CTP)). This is an important indicator by which you can determine the size of the fetus and the approximate gestational age.

Values ​​of the coccygeal-parietal size by pregnancy

Gestation period, weeks	CTE percentile values, mm
10 weeks 1 day
10 weeks 2 days
10 weeks 3 days
10 weeks 4 days
10 weeks 5 days
10 weeks 6 days
11 weeks 1 day
11 weeks 2 days
11 weeks 3 days
11 weeks 4 days
11 weeks 5 days
11 weeks 6 days
12 weeks 1 day
12 weeks 2 days
12 weeks 3 days
12 weeks 4 days
12 weeks 5 days
12 weeks 6 days
13 weeks 1 day
13 weeks 2 days
13 weeks 3 days
13 weeks 4 days
13 weeks 5 days
13 weeks 6 days

Normally, heartbeats should occur at regular intervals, i.e. be rhythmic. Arrhythmia may indicate the presence of a congenital heart defect or fetal hypoxia. The heartbeat should sound very clear and distinct; if there are dull tones, intrauterine oxygen deficiency can be suspected. An important indicator is heart rate.

Normal heart rate by stage of pregnancy

Tachycardia is an increase in the number of heartbeats normal indicators, bradycardia is a decrease in heart rate to 120 beats per minute or less. Most often, such changes in heartbeat occur during fetal hypoxia as a reaction to a decrease in oxygen in the blood. In such cases, the pregnant woman must be prescribed treatment, which is often carried out in a hospital setting. Therapy is prescribed aimed at improving uteroplacental blood flow and improving intracellular metabolism.

• Assessment of the development and presence of various organs(bladder, kidneys, liver, stomach, heart), spine, and also the upper and lower extremities of the fetus. If abnormalities in the development of organs are detected, the woman is referred to a genetic consultation. After a detailed examination, a geneticist decides on the viability of the child and possible termination of pregnancy.

Normal indicators of the second ultrasound at 20-24 weeks

The doctor prescribes a second planned ultrasound at 20-24 weeks. During this period, the following are examined:

1. Biometrics(biparietal size, fronto-occipital size, length of tubular bones, circumference of the abdomen and head). These indicators are measured to assess the growth of the fetus and its size according to the gestational age.
2. Detection of various fetal malformations. It is during this period that diagnostics will be the most informative, because during the first examination, the child is still too small, and during the third planned ultrasound it will already be too big; in addition, at longer periods, the placenta may interfere with a thorough examination if it is located on the anterior wall of the uterus.
3. Structure, thickness, location and degree of maturity of the placenta. This is the most important organ that supplies the fetus with all the nutrients necessary for its normal development.

Normal thickness of the placenta depending on the stage of pregnancy

Gestation period, weeks	Permissible fluctuations	Normal values, mm

If the thickness of the placenta increases, the doctor may suspect the presence of (inflammation of the placenta). Making such a diagnosis requires additional examination for the presence of infection and subsequent treatment in a hospital.

Ultrasound also evaluates degree of maturity of the placenta. This is an important indicator characterizing the ability of the “baby place” (synonymous with the term “placenta”) to provide the fetus with the necessary substances.

Degrees of placenta maturity

Late maturation of the placenta It is quite rare and is mainly caused by:

• Mother's smoking
• She has various chronic diseases.

Premature maturation of the placenta occurs more often. The causes of this condition are:

1. Maternal endocrine diseases (in particular diabetes mellitus),
and even less often - in the bottom area. Normally, the placenta should be 6 cm or more away from the internal os of the cervix.

If it is located lower and overlaps the internal os of the uterus, they speak of. This is a serious type of obstetric pathology that threatens the life and health of the woman and child. Often this anomaly occurs in multiparous women, after inflammatory diseases of the uterus, uterine fibroids, and after abortions. The pregnant woman is carefully observed in the hospital or at home, where she must remain completely at rest and abstain from sexual activity. If bleeding begins, immediate hospitalization is required.

Quantity and quality of amniotic fluid

Average normal amniotic fluid index values

Gestation period, weeks	Possible fluctuations	Average

When quantity changes amniotic fluid in one direction or another they talk about polyhydramnios and oligohydramnios.

Often found in women with infectious diseases, diabetes mellitus, some fetal malformations, Rh sensitization (incompatibility of the blood of mother and fetus according to the Rh factor). The condition requires mandatory treatment: antibiotic therapy, drugs that improve uteroplacental blood flow.

is a pathological decrease in the amount of amniotic fluid less than 500 ml. The causes of this condition are still unknown. If there is very little water, this may indicate a severe malformation of the fetus: the complete absence of kidneys. There is practically no treatment for oligohydramnios; all therapy is aimed at supporting the child.

The ultrasound specialist also evaluates amniotic fluid quality. Normally they should be transparent. If there is turbidity, mucus, or flakes in the amniotic fluid, there is a suspicion of an infectious process. The woman is tested for hidden infections and undergoes treatment.

1. Umbilical cord assessment. Ultrasound examination can detect the entanglement of the umbilical cord around the fetal neck. But in the second trimester of pregnancy it does not cause alarm. The baby is in constant motion, and the umbilical cord can become untwisted.
2. Grade. Normally, the cervix should be at least 3 cm, and only closer to childbirth it begins to shorten and smooth out. The internal opening must be completely closed. Shortening of the neck or opening of the pharynx is a sign. The woman must have stitches placed on her cervix or (a mechanical device in the form of several rings that is inserted into the vagina and protects the cervix from premature dilatation).

Third ultrasound at 32-34 weeks

The third planned ultrasound is performed at 32-34 weeks. Its tasks are:

1. Determination of position and. At this stage, the child is already quite large and his mobility is limited. The position in which he is during the ultrasound will remain until the end of labor. Determining these indicators is important for deciding the method of delivery. There are longitudinal, transverse and oblique positions of the fetus. When the baby is positioned longitudinally, a woman can give birth naturally, transverse and oblique position are relative indications for surgery. Natural birth is also possible with a normal cephalic presentation of the fetus; pelvic position is an indication for surgical delivery.
2. Estimation of fetal size and weight. These indicators help to understand how the child is developing. If the size of the fetus lags behind the average, intrauterine growth retardation may be suspected. Determination of fetal malnutrition requires initiation of treatment for the pregnant woman. If the fruit, on the contrary, is ahead of the indicators, then we can talk about. The birth of a baby with a large weight (more than 4 kg) is likely. This can significantly complicate childbirth, so women are often offered operative delivery.
3. Study of the placenta, its size, degree of maturity and place of attachment. The migration of the placenta at this stage is already completed; it will occupy the same position at birth. It should be taken into account that childbirth is possible only by caesarean section. If the baby's place is low, it is possible to give birth through the natural birth canal, but this is fraught with a high risk of bleeding during childbirth.
4. Assessment of the quantity and quality of amniotic fluid(see topic: normal indicators of the second planned ultrasound at 20 - 24 weeks).

Normal ultrasound before childbirth

Ultrasound examination before childbirth is not mandatory for all pregnant women and is carried out selectively according to indications. Its main task is to resolve the issue of the method of delivery. During an ultrasound, the following is determined:

1. Position and presentation of the child;
2. Estimated fetal weight at birth;
3. Umbilical cord position for exclusion.

From the moment of registration, obstetricians-gynecologists closely monitor the health of the woman and the fetus. Throughout the entire gestation period, the pregnant woman undergoes routine examinations. Some detected problems can be solved medically or surgically, while others require termination of pregnancy. One of the mandatory diagnostic methods that allows you to find out the parameters of fetal development is fetometry. How is fetometry done and what indicators are considered normal?

What is fetometry and what are its purposes?

To have an idea of ​​the child’s development (whether it is progressing normally or if there are abnormalities), doctors need to constantly monitor the fetus’s indicators. One of the routine examinations that is prescribed to all women, regardless of the individual characteristics of gestation, is fetometry.

What does fetal fetometry include? This is a determination of the size of the fetus - height and weight. In ultrasound diagnostics, the following indicators are considered key (their abbreviations in Russian and English language and decryption):

• MP, FW – mass;
• KTP, CRL – coccygeal-parietal size;
• BPD, BPD – biparietal size of the embryo's head;
• DB, FL – size of the femur;
• OB, AC – abdominal circumference;
• OG, NS – head circumference;
• LZR, OFD – fronto-occipital size.

Fetometry is carried out using ultrasound. A pregnant woman undergoes sonography as planned in each trimester - at 11–14 (most often 12) weeks, 18–21 weeks and 32–33 weeks. As a rule, sonography is performed in the usual way through the abdominal cavity or transvaginally. No special preparation for the examination is required; only in the first trimester, before a transabdominal examination, a woman needs to drink 1 liter of water 1 hour before visiting the office in order to bladder was full.

It is impossible to draw conclusions about fetometry alone proper development fetus The child’s parameters will largely depend on his genetic and individual characteristics. If the mother and father are large, then the baby will be ahead of his peers in development. If growth is delayed, a repeat ultrasound scan is required after 2 weeks; often the baby manages to catch up by this time.

What is assessed at the first ultrasound?

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The first screening ultrasound examination is sent soon after the woman is registered. The optimal date for ultrasound diagnostics is 11–12 weeks, but if a pregnant woman contacts antenatal clinic later, she may be referred for sonography immediately. Why is a screening examination prescribed at these times? One of the most significant indicators in the early stages of gestation is the thickness of the nuchal space of the embryo. Previously, this parameter was indistinguishable, but after the 14th week it fills with lymph, distorting the readings.

Normal indicators

At the first ultrasound, the doctor measures the heart rate of the fetus and looks for the presence of vital organs. Also pay close attention to the following parameters:

• TVP is the area between the soft tissues that cover the spine and the inner surface of the skin. Allows you to detect chromosomal abnormalities, such as Down syndrome.
• KTP – coccygeal-parietal size. It is used to calculate the size of the fetus and gestational age.

The table contains the norms for ultrasound results in the 1st trimester:

What does an embryo look like compared to fruit? Until the first month, it resembles the size of a poppy seed. By the end of the second month, it corresponds to a large grape of 5 cm. During the period of the first fetometric study, it is comparable to a ripe fig of 7 cm.

What is considered a deviation from the norm and why?

To determine the norm and deviations in medical practice, the concept of percentiles is used. Among a large sample, the average value is determined - it is called the 50th percentile. The ultrasound norm is within the 5–95 percentile, and everything that goes beyond this range is regarded as a deviation.

Non-compliance with normal values ​​indicates the possibility of intrauterine diseases and developmental anomalies:

• Increased TVP often indicates the presence of genetic pathologies, which include Down syndrome. Its likelihood is indicated by a high TPT, which stands for prenasal tissue thickness. If a discrepancy with the standards is detected, the woman is sent for additional examinations - analysis for alpha-fetoprotein, hCG, amniocentesis, placentocentesis, cordocentesis.
• Irregular heart rhythm may be a consequence of congenital heart disease or hypoxia. Tachycardia and bradycardia may indicate oxygen starvation.
• A high CTE, ahead of the values ​​by 1–2 weeks, is considered normal by doctors. Most often, this indicates that the child will be large. If the mother has diabetes mellitus or the likelihood of developing Rh conflict is increased, then additional examinations are required.
• If deviations in the anatomy of the fetus are detected (incorrect anatomy of the bones of the cranial vault, spine, stomach, heart, limbs, abdominal wall), the sonologist enters them in a special column. Together with an obstetrician-gynecologist and, if necessary, geneticists, a conclusion is made on the advisability of prolonging gestation.

What indicators are studied in the second trimester?

Previously, ultrasound diagnostics in the second trimester were performed at the 25th week of pregnancy, but now they are performed at the 4th month of gestation. This is due to the need to detect malformations at an earlier stage. In addition to the parameters of the fetus, during this period the child's place, its size and degree of maturity are studied.

Standard sizes

In the second trimester of pregnancy, you can better see the size of the baby and specific organs. During this period, more attention is paid to the following ultrasound indicators:

• baby's weight;
• height;
• abdominal circumference;
• fronto-occipital size;
• biparietal head size;
• shin size;
• thigh length;
• humerus size;
• forearm bone length.

The table shows the results of fetometry in the 2nd trimester in accordance with the protocol:

Gestation week	Weight, g	Length, cm	Coolant, mm	OG, mm	LZR, mm	BPR, mm	DG, mm	DB, mm	DP, mm	DCP, mm
Week 16	100	11,6	88–116	112–136	41–49	31–37	15–21	17–23	15–21	12–18
Week 17	140	13	93–131	121–149	46–54	34–45	17–25	20–28	17–25	15–21
Week 18	190	14,2	104–144	131–161	49–59	37–47	20–28	23–31	20–28	17–23
Week 19	240	15,3	114–154	142–174	53–63	41–49	23–31	26–34	23–31	20–26
Week 20	300	16,4	124–164	154–186	56–68	43–43	26–34	29–37	26–34	22–29

At the second screening study, it is already possible to assess the size of the placenta. At week 20 it ranges from 1.67–2.86 cm. Amniotic fluid index by week:

• 16 – 74–202;
• 17 – 78–212;
• 18 – 81–221;
• 19 – 84–226;
• 20 – 87–231.

What do deviations from the standard indicate?

Advanced maturation of the placenta is most often observed in mothers who smoke. In addition, this indicator is influenced by the presence diabetes mellitus, development of gestosis, the appearance of intrauterine infections.

Polyhydramnios indicates defects in the development of the child, Rh conflict. Oligohydramnios indicates severe abnormalities in intrauterine development, pathologies, or absence of kidneys in the fetus.

Visualization may be difficult due to the high content of subcutaneous fat. In this case, the doctor indicates in the protocol the cause of the difficulty - PZhK.

The second screening ultrasound allows you to detect pathologies of fetal development that were not visible during the first examination:

• developmental delay if the indicators are symmetrically below the specified norm;
• asymmetrical reduction of the femur, humerus, tibia and forearm indicate skeletal dysplasia;
• an enlarged skull indicates hydrocephalus;
• by measuring the face one can judge the presence of pathologies such as cyclopia, anophthalmia, cleft lip and palate;
• scanning the spine helps to detect spinal bifida;
• absence, underdevelopment or abnormal structure internal organs indicate intrauterine anomalies incompatible with life.

Fetal fetometry parameters in the third trimester

The third ultrasound of the fetus is prescribed for 32–33 weeks of gestation, although according to individual indications the period can be shifted by several weeks. During this period, the baby is already fully formed, and it becomes possible to evaluate developmental defects that were not visible before. Particular attention is paid to the placenta and amniotic fluid, as well as fetal presentation.

Table of normal sizes of the fetus, body parts and organs

Final fetometry is important, because it is based on its results that doctors choose the method of conducting the birth process. In the final trimester, the average data on the baby's size and weight are also assessed.

The table shows the average fetometry indicators in the third trimester:

On an ultrasound, the obstetrician-gynecologist looks at the presentation of the fetus, and the delivery tactics depend on this:

• direct cephalic presentation - natural delivery;
• oblique, transverse or direct breech presentation – C-section(usually).

Possible deviations and their interpretation

Deviations from normal indicators make it possible to predict possible complications during the birth process and detect congenital malformations. Interpretation of deviations:

• Weight and height are greater than normal. A large baby will complicate the delivery process. This may be an indication for surgical intervention, otherwise the woman in labor will experience ruptures as the baby passes through the birth canal.
• Low location of the placenta. In such a situation, natural childbirth is acceptable, but the risk of bleeding is high.
• In the third trimester, abnormalities that were not apparent before become visible. At the last examination, a cleft lip, cleft palate, and aneurysm of the vein of Galen can be detected.
• Indicators below normal allow one to diagnose developmental delay syndrome. This diagnosis allows timely measures to be taken to maintain the baby’s life.

Rules for decoding the ultrasound result by a specialist

Interpretation of ultrasound during pregnancy is performed only by a sonologist, and the diagnosis is made by an obstetrician-gynecologist, who is based on ultrasound diagnostic indicators and other methods. The calculation of indicators is carried out according to obstetric weeks, which are counted from the date of the last menstruation. In fact, the fetus is 1.5–2 weeks younger, but to avoid errors in calculations, gynecologists use a system of counting from the first day of menstruation.

One of the basic rules that guide specialists when interpreting ultrasound is not to make a diagnosis based on sonography results alone. If an abnormal course of gestation is suspected, the pregnant woman is prescribed a re-examination and referred for additional diagnostics.

Despite the fact that the ultrasound report indicates specific numbers - limb length, volume, height and weight, you should not try to interpret them yourself. The limits of the norm indicators are large; borderline data do not necessarily indicate deviations, but to the expectant mother you need to protect yourself from stress.

At various stages of pregnancy, fetometry is regularly performed - this is determining the size of the fetus using ultrasound. The data obtained during the examination were subjected to statistical analysis over many years, and on their basis a table was compiled with normal indicators by week.

It is the main parameter for more accurately determining the due date and allows you to find out whether there are any abnormalities in the baby’s intrauterine development. Knowing what it is, young parents themselves can, after an ultrasound examination, make sure that everything is in order.

Most often, ultrasound fetometry is performed either with a transvaginal sensor or traditionally through the abdomen. In the first case, no preparation is required from the woman. Classic ultrasound will show more accurate results if early stages An hour before the procedure, drink 500 ml of water and do not empty your bladder. When filled, it will help improve visibility in the uterine cavity. After 12 weeks, this will no longer be necessary, since this function will be performed by amniotic fluid.

The procedure is familiar to everyone: a special gel is applied to the stomach, and everything that happens in utero is displayed on a computer monitor. Modern programs allow you to automatically take measurements of the fetus, and the doctor then compares them with a general table of norms by week. This allows you to clarify the duration of pregnancy and timely identify pathologies in the development of the fetus.

Why is it called that? The term “fetometry” goes back to the Latin word “fetus” (translated as “offspring”) and the Greek “metreo” (meaning “to measure, determine”).

Norms and deviations

It is useful for parents to know what the norm is, according to the fetometry table, and when they talk about pathological deviations. Seeing a slight discrepancy between the true sizes and official indicators, many begin to panic and draw incorrect conclusions, which in most cases turns out to be completely in vain.

• the fetal data fully corresponds to the sizes in the table;
• they are behind or ahead of them by less than 2 weeks (this period is acceptable for individual characteristics);
• the indicators are not on the same line, but scattered, but this difference is no more than 1 line: these discrepancies are acceptable due to the spasmodic intrauterine development of the fetus.

Everything else is referred to as cases of deviations. It is especially dangerous when the fetometry of the fetus shows for the umpteenth time that the same size is 2 or even more lines larger or smaller than the norm.

For example, a growing head circumference may indicate, but to confirm the diagnosis, additional data obtained during Doppler and CTG, and dynamic observation will be needed.

For comparison. If all the dimensions of the fetus “fit” into the norm indicated in the fetometry table, except, for example, the length of the thigh, this is not at all an indicator of pathology. Perhaps the parents or other relatives of the child are simply the owners of very long (or, conversely, too short) legs.

If there are deviations, such serious diagnoses as "", "", are confirmed by two doctors: not only an obstetrician-gynecologist, but also a medical geneticist. They assess the genetic predisposition of the fetus and determine the causes of the identified pathology (chromosomal abnormalities, bad habits, parental age, intrauterine infection, etc.).

It is very important that the obstetrician-gynecologist deciphers the obtained indicators first of all: the ultrasound specialist only provides him with a summary sheet, which indicates what sizes and how much they differ from the norm of fetometry for a given stage of pregnancy. What parameters are taken into account during screenings?

Description of the main indicators

To understand what fetal fetometry data is contained in the tables by week, you need to know symbols these parameters and their interpretation.

• BDP - biparietal size, the distance between the parietal bones, describes the development of the nervous system.
• DB - thigh length.
• DG - length of the lower leg.
• DN - length of the nasal bone.
• DP - shoulder length.
• KTP - coccygeal-parietal size.
• LZR - fronto-occipital size.
• OG - head circumference.
• OG (DHA) - breast volume (chest diameter).
• OB - abdominal circumference.
• PDA - transverse diameter of the abdomen.
• PY is the fertilized egg where the baby develops.
• SDA - sagittal diameter of the abdomen (measured in the anteroposterior direction).
• TVP - thickness of the collar space.

This is the breakdown of the indicators that are most often indicated in the fetometry table. It may also include the lengths of other bones - tibia, fibula, ulna, radius, as well as the foot. But they no longer have such importance for identifying pathologies - they are used for comparison only as additional information.

Among other things, you can calculate the weight of the fetus using fetometry performed after the 20th week of pregnancy. All calculations are made automatically by the ultrasound machine itself based on the period, BPR, LZR, coolant, DB and exhaust gas. They give very accurate results and allow you to compare them using a table with standards.

I trimester

The first fetometry is prescribed at 12-13 weeks. Its goal is to identify malformations in the fetus in the early stages of pregnancy.

This ultrasound screening does not determine a specific disease, but only indicates markers that are typical for it. Based on the results obtained, additional studies may be prescribed. All suspicions that arise are confirmed or refuted by invasive laboratory techniques.

Some fetometry indicators may be specified. For example, during the first screening, specialists use a table of average CTE values, since this size is very important for identifying abnormalities in the intrauterine development of the fetus.

Doctors consider an increase in CTE for 1-2 weeks as normal variants. If the pregnancy is not complicated by Rh conflict, this may mean that the baby will be born a real hero and his weight will be more than 4 kg, and this in some cases may be an indication for the procedure.

These are the important data that the first fetometry gives to specialists.

About the timing. The first ultrasound screening is carried out during this period due to the TVP indicator. Until the 11th week it is so small that it cannot be measured. And after 14 weeks, this space is filled with lymph, which distorts the results of the study. It is this parameter that is a marker of most chromosomal abnormalities of the fetus.

II trimester

The time frame for the second ultrasound fetometry must fit within the following periods:

• no earlier than 16 weeks;
• no later than 20;
• the best option is week 17, which, if abnormalities are detected, will allow more accurate additional genetic examinations;
• Sometimes an ultrasound is performed at 21-22 weeks, but these are already the most extreme and undesirable dates.

The first ultrasound screening provides the most accurate results, but often even these are not enough to make a reliable diagnosis. To do this, many indicators need to be seen in dynamics. This is precisely what the data from the second fetometry demonstrates.

It performs the following tasks:

• identify defects that cannot be determined in the first trimester;
• confirm/refute the diagnosis previously made based on the results of the first screening;
• determine the risk level of suspects;
• detect deviations in the formation of a small organism.

Fetometry of the second trimester is prescribed only to those women who, according to the results of the first ultrasound, are at risk.

Approximate ultrasound standards at this stage of pregnancy are presented in the following tables.

Height Weight

Abdominal circumference

Head circumference

Shin length

Thigh length

Humerus length

Forearm bone length

If for some reason the timing of the second fetometry was shifted, you can use a table with average indicators from 21 to 27 weeks:

After studying the data from the second fetometry, the gynecologist can refer the woman for a consultation with a geneticist or independently prescribe invasive techniques to diagnose suspected pathologies. In cases where the diagnosis is nevertheless confirmed, a decision is made on the further fate of the pregnancy.

If therapeutic adjustment is not possible, artificial induction of labor is performed (read about artificial childbirth). If the detected pathology is reversible, treatment is prescribed as quickly as possible to save the baby.

III trimester

The third fetometry can be prescribed on any day of the third trimester of pregnancy. The optimal period is 32-33 weeks. Since at this stage it is close to childbirth, ultrasound is performed more carefully than before.

For example, the baby’s face is already clearly visible, which makes it possible to identify pathologies such as cleft palate or cleft lip. The doctor finds out how developed the fetus is in accordance with the gestational age.

It is usually not recommended to conduct such studies after 34 weeks. However, there are cases when they are prescribed immediately before birth (at 37-38 weeks) in order to make a final decision about a caesarean section or.

Table of average values ​​of the third fetometry by week

If there are deviations at this stage, the woman is offered hospitalization. If the obtained readings change negatively, doctors may decide to induce premature labor.

Helpful information. Everyone around (women, and often doctors themselves) likes to talk about the importance of the first two fetometry and the optionality of the third. But only she allows you to make the right decision on how to conduct the upcoming birth with minimal losses for mother and baby.

The information from the fetal fetometry tables is for informational purposes only. It is not recommended for parents to draw any independent conclusions by comparing the results obtained with the norms, because they do not always reflect reality and require mandatory interpretation by specialists.

Every pregnant woman undergoes ultrasound screening, which monitors the condition and size of the fetus. There is a table of normal fetometry values ​​for each week of gestation. Using them, the gynecologist determines the dynamics of the child’s development and the absence of congenital pathologies.

The name of the study consists of two words: Latin “foetus” and Greek “metreo”. They mean "fruit" and "measure" respectively. Fetometry is the measurement of the size of an embryo. Based on screening data, the gynecologist determines the development of the embryo, the presence of abnormalities and the gestation period.

Each measurement is recorded by special devices and recorded, giving values ​​in millimeters. The ultrasound specialist enters these results into a table where the measurements taken and their acceptable values ​​are indicated.

Fetal fetometry by week (a table of indicators, understandable and correctly filled out, the professionalism of an obstetrician-gynecologist - all this makes it easier to control the development of the embryo, helps to notice and stop any problems in time possible problems) allows you to determine the date of delivery with an error of several days.

When and how does the research take place?

Pregnancy is divided into 3 stages, in each of which one ultrasound is performed. If necessary, the gynecologist prescribes additional examinations.

Fetal measurements are taken:

• at 12-14 weeks - first trimester;
• at 20-22 weeks - II trimester;
• at 30-32 weeks - III trimester.

The timing of screening may be changed by the attending physician.

They depend on:

• well-being of a pregnant woman;
• previous studies;
• there are suspicions of abnormal development of the embryo or pathological processes during gestation.

When undergoing an ultrasound scan in the first trimester, the ultrasound specialist clarifies the gestation period and sets a preliminary date for delivery. During this period of pregnancy, it is important to diagnose early congenital pathologies and intrauterine malformations of the embryo.

The most informative will be data on the coccygeal-parietal size (CTR), abdominal circumference, nose size and width of the cervical fold.

After this, the ultrasound specialist will determine:

• heartbeat;
• blood circulation;
• location of the embryo in the uterus.

Fetometry in mid-pregnancy is a key study to confirm the absence of pathologies.

This ultrasound determines:

• biparietal size (BPR);
• Head circumference;
• abdominal girth;
• size of the frontal bone and occipital part;
• thigh length;
• humerus bone size.

At this time, the ultrasound specialist can already accurately indicate the gender of the child.

In the later stages, the gynecologist checks only the well-being of the child, as well as some measurements:

• length;
• head circumference;
• belly size.

The doctor also looks at the symmetry of growth of all limbs. The data obtained determines what kind of birth there will be: natural or through a caesarean section. If the results of the study are normal, then no further ultrasound examinations are performed.

The fetometry procedure is the same as a regular ultrasound:

• Transvaginally in the early stages, since it is difficult to accurately determine all fetal indicators through the abdominal wall. A special sensor, on which a condom is placed before the procedure, is inserted into the vagina.
• Transabdominal. This method is suitable if the specialist can clearly see the child through the abdominal muscles. A small amount of gel is applied to the skin of the abdomen and the sensor is passed over the entire abdominal area.

Fetal fetometry by week: a table recording the weekly growth of the child with weight and CTE indicators

It is customary to carry out both types of examinations at once in order to obtain error-free results of measuring the fetus. It is advisable to carry out the first and second screening with a full bladder, and on last weeks the uterine cavity is clearly visible due to the accumulation of amniotic fluid.

Basic nuances of fetal examination

Fetal fetometry week by week makes it possible to determine its length and size of body parts. The table with the entered measurements clearly shows the dynamics of fetal formation at each stage of gestation. But the child’s growth is uneven, and the indicators may not coincide with the acceptable values.

Due to the hereditary characteristics of each organism, differences in characteristics from the table values ​​may be acceptable and not reflect developmental pathology. The mother or father may be tall and thin or, conversely, short and rather densely built - these hereditary factors affect the examination indicators.

The numbers obtained from it will differ greatly from the table values.

For this reason, conclusions about a child’s developmental abnormality based on one measurement of ultrasound screening are not made, but additional studies are prescribed. When pathologies are confirmed by an obstetrician-gynecologist and geneticists, a preliminary diagnosis is made - “intrauterine developmental delay.”

This diagnosis has 2 forms:

• asymmetrical when only some indicators differ from normal at a given stage of pregnancy;
• symmetrical, at which all indicators decrease.

Developmental delay has several degrees, differing in the severity of pathologies:

• I degree: data differ from normal values ​​by 2 weeks;
• II degree: data differ by 3 weeks;
• III degree: the difference in indicators is 4-5 weeks.

Fetal fetometry by week and a table that describes the dynamics of the child’s development are not absolutely accurate. Figures that differ from the statistical average may be a diagnostic error. After some time, the obstetrician-gynecologist will prescribe a repeat ultrasound screening.

Often the parameters of the fetus reach the desired value after a while.

Key indicators of fetometric research

Fetal fetometry by week (a table of measured values ​​and accepted norms, which is attached to the research responses, allows you to independently decipher the results) and a biochemical blood test are a full-fledged set of studies that complement each other.

Thus, ultrasound screening alone, carried out even with the most innovative devices, is not informative until the 11th week due to the short length of the fetus. That is why the doctor prescribes examinations only at certain times.

The main parameters of fetometry are:

1. Weight. This parameter is monitored throughout pregnancy. It characterizes the health and vitality of the child, and is also one of the decisive factors for choosing the type of birth. On average, healthy children gain weight from 10 to 100 g weekly. But here, too, slight deviations are possible due to the genetic characteristics of the child.
2. coolant- abdominal girth or circumference. It is not measured if the fetal weight exceeds 4 kg. It determines the formation of internal organs.
3. KTR- coccygeal-parietal size. This is the length of the fetal body without taking into account the size of the head: from the fontanel to the coccyx. It is used to determine the gestation period until the embryo reaches 6 cm.
4. BPR- biparental size. This is the circumference of the embryo's head. It is measured between the temples. According to it, the obstetrician-gynecologist monitors the formation of the brain and sets the gestation period with a certainty of 10 days.
5. DB- thigh length. This indicator is used to check the child’s skeleton, or rather the absence of joint dysplasia. DB is measured only in the absence of BPR measurements. It helps to find out the date of conception and time of gestation.
6. OG(DHA) - breast diameter. After 23 weeks, this parameter ceases to be informative. It is used only to analyze the general health of the child in combination with other characteristics.

If necessary, measure the following parameters:

• occipital bone size;
• nose size;
• width of the neck fold;
• half abdominal circumference: from the umbilical cord to the spine;
• contours and size of the fertilized egg;
• shoulder size;
• head size and shape.

Is not full list measured parameters during fetometry.

This also includes bone measurements:

• tibia;
• tibia;
• ray;
• elbow;
• brushes;
• Feet.

These parameters have no significance for identifying various anomalies and are defined only for the sake of additional information.

Baby's weight

This measurement is of great importance for the developing and growing embryo. With its help, the obstetrician-gynecologist monitors the child’s condition and assesses the likelihood of abnormalities. With timely detection of abnormalities, the development of many intrauterine diseases can be prevented.

The increase should be up to 100 g weekly, and several kilograms between screenings. It must be remembered that individual characteristics the child’s body can shift the size of the increase up or down from the table values.

The main thing when monitoring fetal weight is the dynamics of weight gain, not its decrease.

KTR

The results of the distance from the crown to the tailbone of the fetus are entered into the table of the results of the first screening. This is the main parameter when conducting research in the first trimester of pregnancy. It is strictly controlled until the child reaches a length of 6 cm.

Based on the coccygeal-parietal size, the date of conception and gestational age are determined with an accuracy of 7 days.

The CTE indicator is not informative in the 2nd trimester of pregnancy, since fetal growth during this period is determined by heredity. Jumps in this parameter may go beyond normal values, so in the second screening the main parameter is the distance between the parietal bones.

If the CTE indicator increases for a couple of weeks, a repeat examination of the mother is prescribed to identify pathologies such as:

• diabetes;
• Rh conflict between mother and child;
• tumors.

In the absence of these problems with the mother's health, an increase in the distance between the crown and the tailbone indicates a large size of the fetus. At the time of birth, he may weigh more than 4 kg.

When carrying particularly large children, it is necessary to carefully and under the supervision of an obstetrician-gynecologist take various medications, especially vitamin complexes and food additives. Abuse of such drugs can increase a child’s weight by up to 5 kg., which will provoke a difficult birth.

A decrease in CTE may also be normal, or may indicate a pathology of fetal development.

This result when measuring CTE is considered normal if late ovulation and late fertilization have occurred. No modern ultrasound machine can detect such a difference in timing. In this case, the time of conception shifts and does not coincide with the time calculated from the woman’s menstrual cycle.

To clarify the situation, the obstetrician-gynecologist prescribes repeat fetometry after 7 days.

A decrease in the distance from the crown to the tailbone may indicate pathologies:

1. Weak production of progesterone. After additional tests, the attending gynecologist prescribes a hormonal treatment regimen. If its recommendations are not followed, spontaneous miscarriage may occur.
2. Infectious diseases of the mother or infection of the fetus. These include sexually transmitted diseases. They not only interfere with the child’s normal weight gain, but can also cause serious abnormalities. The attending physician prescribes the necessary blood, urine and stool tests to determine the type of infection. After this, he prescribes the required and effective treatment.
3. Damage to the uterine mucosa. Erosion, fibroids or a previous abortion injure the mucosal tissue. Because of this, the fertilized egg is not able to firmly attach itself to the walls of the uterus, which threatens spontaneous termination of pregnancy.
4. Genetic diseases. These include Down syndrome, Edwards syndrome and others. To confirm them, a genetic examination is required. Severe forms of pathologies end in miscarriage.
5. Non-developing pregnancy(frozen). This pathology provokes the death of the fetus and threatens the mother:

• opening of bleeding;
• infertility;
• anaphylactic shock;
• fatal.

If this diagnosis is confirmed, the woman requires immediate surgery. This pathology is excluded by listening to the child’s heartbeat on an ultrasound.

BPR

Biparental indicators are the main parameter in mid-pregnancy. It shows the maturity of the brain and the compliance of the fetus with the gestation period. BPR is measured between the temples along the eyebrow line. Sometimes, together with it, the distance between the forehead and the posterior fontanelle is determined along the outer borders of the frontal and occipital bones (LZR).

BDP indicators help to determine the degree of safety of childbirth for a woman and her child. If BPR values ​​are higher than normal, the pregnant woman is prescribed a planned cesarean section. The combination of the BPD and LZR parameters determines the development of the child’s nervous system and brain.

A distinctive feature of these characteristics is a decrease in growth rate with increasing gestation period.

As with KTR, jumps in BPR and LZR relate to both normal and pathological development of the fetus. A deviation of all values ​​by 4 weeks is considered normal when the child weighs more than 4 kg, since his growth is uneven. To confirm a positive result, the obstetrician-gynecologist prescribes a repeat ultrasound in a few weeks.

Increased biparental indicators can also be a pathology and indicate the presence of abnormalities of bone tissue and brain:

• neoplasms;
• hernias;
• hydrocephalus;
• accumulation of fluid in various parts of the brain.

If these pathologies are confirmed, the obstetrician-gynecologist will give recommendations to the pregnant woman:

• in case of hernias and neoplasms - termination of pregnancy, since the fetus with such complications dies at a later stage;
• for hydrocephalus or dropsy - treatment with antibiotics, and negative results are advised to terminate the pregnancy.

A decrease in BPR and LZR always indicates pathologies:

• Underdevelopment of the brain structure or its complete absence. In this case, the woman is immediately operated on, regardless of the gestation period and the stage of the complication.
• Deviation from the timing of development. In this case, medical intervention and correction of the fetal condition are necessary. In their absence, the fetus dies.

Together, the BPR and LZR determine the shape and circumference of the fetal head.

Determination of thigh length

Measuring the length of the thigh is an equally important indicator. It establishes the possibility of underdevelopment skeletal system . An ultrasound specialist takes a measurement of the femur if the device was unable to display the BPR parameter or the shape of the fetal head has changed significantly.

The length of the femur determines the gestation period to within a week. Determining the size of other bones to determine the gestational age is not highly accurate.

Abdominal circumference

If the child weighs more than 4 kg, this parameter is not determined. The volume of the abdomen characterizes the development of the internal organs of the fetus: stomach, ductus venosus, intestines, gall bladder, and so on. Using an ultrasound, an obstetrician-gynecologist monitors the formation and growth of internal organs.

Abdominal girth is not as precise as femur size, but is used as a key indicator when suggesting intrauterine growth retardation.

Chest volume

Breast diameter is a highly informative parameter in the 2nd trimester of pregnancy, but to assess the condition of the fetus, other parameters are studied along with it. Based on the volume of the chest, the obstetrician-gynecologist determines the development of the chest organs: heart, lungs, thymus and trachea, and also assesses the risk of developing skeletal dysplasia.

Chest circumference is not always measured; it is only informative if other parameters are available and cannot serve as a basis for making a diagnosis.

Table: norms of fetal photometry by week

After undergoing screening in each trimester of pregnancy, parents want to make sure that the child is developing normally. To make it easier for parents and doctors to navigate the measurements taken, there is a general system of standards.

Fetal fetometry by week: table of limit values ​​of key parameters.

	KTE, mm	Weight, g	BPR, mm	DB, mm	Coolant, mm	DHA, mm
12	42-73	13-25	22-24	7-11	50-71	21-25
13	51-87	25-37	25-27	10-14	58-79	22-26
14	87-150	37-60	28-30	13-19	66-91	24-28
15	140-159	60-88	31-33	15-20	85-103	26-30
16	153-172	88-130	34-37	17-23	88-115	28-36
17	170-195	130-180	38-41	20-28	93-130	36-40
18	195-212	180-230	42-47	23-31	105-144	39-43
19	215-238	230-290	48-49	26-34	114-154	42-46
20	238-250	290-382	50-53	29-37	125-163	46-50
21	250-275	382-458	54-56	35-39	137-177	48-52
22	275-290	458-552	57-60	37-43	148-190	51-55
23	293-320	552-630	61-64	40-46	160-201	54-58
24	310-322	630-754	65-67	42-50	173-223	57-62
25	322-335	754-870	68-70	46-50	183-228	60-64
26	335-345	870-990	71-73	49-58	194-240	62-66
27	345-360	990-1200	75-76	53-60	206-253	67-71
28	359-385	1200-1350	77-79	54-61	217-264	71-75
29	382-396	1350-1500	80-82	55-62	228-277	74-78
30	396-405	1500-1690	83-85	56-62	238-290	77-81
31	400-428	1690-1800	86-87	59-65	247-300	79-83
32	425-437	1800-2000	88-89	60-66	258-314	81-85
33	432-440	2000-2200	90-91	63-69	267-334	83-87
34	438-450	2200-2320	92-93	64-69	276-336	86-90
35	446-460	2320-2600	94-95	65-71	285-344	89-93
36	458-470	2600-2700	96-97	67-72	292-353	92-96
37	469-480	2700-2885	98-98	68-74	300-360	95-99
38	478-498	2885-3000	99-100	70-76	304-368	97-101
39	493-510	3000-3223	101-102	72-78	310-375	99-103
40	505-538	3223-3400	103	74-80	313-380	101-105

There is also a separate table of accepted CTE values, since this indicator is most informative only in the first weeks of gestation until the fetus reaches a size of 60 mm.

Week of pregnancy, obstetric	Fruit size, mm	KTE, mm
5	03-1,0	1-4
6	0,9-1,3	3-8
7	1,0-1,5	7-12
8	1,3-2,0	11-18
9	2,1-2,7	17-23
10	2,7-3,8	24-40
11	3,5-4,5	26-53

Is research harmful?

The ultrasound procedure is completely harmless. The waves produced during the test are high-frequency sounds that are not detected by the human ear.

• does not affect the condition of the skin;
• not capable of causing pathologies of internal organs;
• does not affect the course of pregnancy.

The high frequency of the waves causes slight vibrations in the tissues, which do not change their structure in any way. Also, ultrasound does not have an effect cumulative effect, which has been proven by scientific research. When performing fetal photometry, several factors are taken into account: the course of pregnancy and the woman’s health.

It is worth remembering that each child’s body is individual and hereditary characteristics can affect the values ​​obtained. Because of this, they may differ from the table parameters. To confirm the normal development of the child, it is necessary to undergo a screening ultrasound after a few weeks.

Article format: E. Chaikina

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