Norms of the length of the femur by weeks table. Ultrasound and dopplerometry in the II trimester. The role of ultrasound

Introduction

Accurate knowledge of the gestational age is important for assessing the nature of fetal development, diagnosing certain congenital malformations, choosing the optimal term for terminating a pregnancy and setting the date for issuing prenatal leave (especially for 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, overpregnancy, choosing the optimal method of delivery in the presence of a large fetus, diagnosing its malnutrition and developmental anomalies.

In this paper, for the first time, we present statistics data obtained from the surveyed group of women whose gestational age was verified on the basis of in vitro fertilization (IVF) data. At the same time, 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 of individual parameters of fetometry established by us and a computer program created on their basis for calculating the gestational age, weight and growth of the fetus in the I, II and III trimesters during a physiologically developing pregnancy.

Materials and methods

Ultrasound examination was performed on 155 women with in vitro fertilization (group 1), 40 of them 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. Fetal weight averaged 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 the weight of the fetus 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 regarded as normal, in connection with which the presence of a healthy low-weight fetus was stated.

During fetometry, the coccyx-parietal size of the embryo (in the first trimester), the biparietal size and the frontal-occipital size of the fetal head, the average diameter of the abdomen (W), the length of the femur (DB), tibia (Bb) and humerus (HB) were measured, foot length (St), mean fetal heart diameter (C), interhemispheric cerebellar size (MRM), mean fetal head size (D). The coccygeal-parietal size of the embryo was measured by longitudinal scanning from the parietal bone to the coccyx with the head of the embryo bent (Fig. 1).

Rice. 1.

The biparietal size was measured by visualization of the M-echo at the level of the third ventricle of the brain, at the same distance from the parietal bones, when obtaining an image of the cavity of the septum pellucidum and the quadrigemina. The measurement was made from the outer to the inner contour of the parietal bones. The determination of the fronto-occipital size was carried out 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 mean heart diameter was taken as the arithmetic mean of two maximum mutually perpendicular heart sizes measured in diastole during transverse scanning at the level of the leaflets (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 its 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 by the maximum distance between the extreme lateral boundaries of its opposite hemispheres (Fig. 5). In case of insufficiently clear visualization of the entire cerebellum, 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 obtained 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 diaphyses was taken as the length of the femur, tibia, and humerus (Fig. 6a, b). Foot length was defined as the distance between the distal phalanx of the big toe and the calcaneus.

Rice. 6.

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

Research results

This paper provides normative tables for determining the compliance of individual parameters of fetal biometrics with gestational age (Tables 1-11). At the same time, the analysis of fetometry data in the first trimester (Table 12) showed that the equation we obtained for determining the gestational age 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. The coccygeal-parietal size of the embryo, see Fig.

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 fact that the sum of% is not equal to 100 is normal) - approx. typesetter.

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

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 (LZR), see Fig.

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. The average size of the fetal head (G), 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 (MRM), see.

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. Mean 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. The average diameter of the abdomen (W), 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. The length of the fetal humerus (DP), 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. The length of the femur of the fetus (DB), 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. Fetal tibia length (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 the weight of the fetus in the second trimester of pregnancy (Table 14), according to different authors, it turned out that the calculated values ​​correspond to the actual ones only in J.C. Hobbins. The accuracy of determining the weight of the fetus in these periods of pregnancy, according to our data, is quite high; the average error was 27.6±27.8 g (6.5% of its mass). When using J.C. Hobbins, it turned out to be significantly higher and averaged 60.3±55.8 (14.2% of the fetal weight). At the same time, a slight error in determining the weight of the fetus, which is less than 20 g, in our observations occurred in 55.5% of cases, and when using the J.C. Hobbins - at 20.6%.

At present, we have not come across any reports indicating the possibility of ultrasound determination of fetal growth in the second trimester of pregnancy. The data presented by us indicate the possibility of establishing fetal growth in these terms of pregnancy with a sufficiently high accuracy. The use of computer fetometry proposed by us showed that the average error in determining the growth of the fetus was small and amounted to 0.76±0.84 cm (2.9% of its growth). A slight error in determining the growth of the fetus, not exceeding 1 cm, was stated in 81.3% of observations.

When determining the calculated value of the fetal weight in the third trimester in the case of a physiologically proceeding 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 stated using the criteria of J.C. Birnholz - 279.6±199 g (7.9% of the fruit weight) and F.P. Hadlock - 307.4±219.2 g (10% of the weight of the fetus), 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 computed fetometry, was recorded in 65.3% of cases using J.C. Birnholz - in 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 according to the equations and tables of the above authors, the calculation was not always possible (in particular, this was observed with large fetuses or pronounced asymmetry in the size of the abdomen and head or abdomen and thighs).

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

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

Discussion

The analysis of the data obtained indicates a sufficiently high accuracy of the computer fetometry proposed by us to determine the gestational age throughout pregnancy, as well as the weight and growth of the fetus in the II and III trimesters of pregnancy compared with the programs of other authors, which are currently widely used in modern ultrasound equipment. .

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

In the III trimester of pregnancy, the average error in determining the 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.

The 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. 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 the weight of the fetus, exceeding 400 g, was 4 times less common in our observations than when using the criteria of J.C. Birnholz, 5.3 times less than according to F.P. Hadlock, 5.7 times less than according to J.C. Hobbins and M.J. Shepard and 8.8 times less often than according to S. Campbell (see Table 13). Pretty accurate results, in our opinion, were also obtained when determining the growth of the fetus (see Table 15).

Thus, the presented data indicate that ultrasonic computerized fetometry is a valuable method, the use of which allows to establish the term, weight and growth of the fetus with a fairly high accuracy 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.

The interpretation of ultrasound readings is carried out by two specialists - a doctor who conducts an ultrasound examination, and a leading gynecologist. The ultrasound doctor issues a conclusion with the established gestational age and information about the existing pathologies of fetal development or their absence. The gynecologist also assesses the degree of pathologies and decides what to do next for the pregnant woman.

Why do you need an ultrasound during pregnancy

Conducting an ultrasound analysis is caused by the need to examine the child in the womb for its pathologies or their absence.

Early ultrasound is carried out to determine the presence of pregnancy and its duration, the number of fetal eggs. This way of research is useful in that it can reveal an ectopic pregnancy - a dangerous condition that requires immediate medical intervention, up to surgical methods. If, with the help of ultrasound, this pathology is detected in the initial stages, the pregnant woman has the opportunity to avoid surgical intervention.

At the stage first screening (11-13 weeks) the walls of the uterus, the uterus itself and its appendages are studied, and the following indicators of the growth of the embryo are considered:

• chorion - it contributes to the development of the placenta;
• The yolk sac is an important component for the development of the embryo.

At the next ultrasound helps to identify existing pathologies, such as, the threat of miscarriage,. It is the timely diagnosis of deviations that helps to eliminate them and avoid subsequent complications.

At the second screening a number of indicators are examined, which then will need to be deciphered:

• the uterus, fallopian tubes and the condition of the ovaries are examined;
• fetometry is carried out, with the help of which the sizes of individual parts of the fetus are established and their compliance with the gestational age is assessed;
• the state of the organs that connect the child with the mother (placenta, umbilical cord) is studied, the structure of the amniotic fluid is assessed;
• the state of the internal organs of the child is analyzed.

On this ultrasound, some pathologies can be traced, such as oligohydramnios or too low attachment of the placenta. Thanks to ultrasound, it is possible to establish both curable and incurable fetal defects.

Third screening carried out for the following purposes:

• identification of serious fetal malformations that cannot be detected in the early stages;
• determination of fetal presentation (gluteal or head);
• determination of the body weight of the child;
• assessment of the risk of abnormal formation of the brain;
• examination for a subject;
• evaluation of the fetal heart rate - rapid or rare;
• assessment of fetal growth;
• assessment of the risk of developing heart defects in the fetus.

On ultrasound in the third trimester, you can already see the baby's lungs and their readiness to work in a normal environment in case of premature birth. In the last screening, great attention is paid to the skull, abnormalities such as cleft palate, cleft lip, etc. are monitored.

On the eve of the birth itself, ultrasound allows you to find out some of the nuances that may be important for the birth process itself. In particular, only thanks to ultrasound it is possible to see the entwined umbilical cord with 100% accuracy, and this is a very important aspect in the birth process, because it can become a threat both to the health of the baby and to his life.

Some pregnant women are prescribed Ultrasound more often than expected. These pregnant women include those who have: diabetes mellitus, blood and lymph diseases, negative Rh factor.

Deciphering fetal ultrasound

Already starting from the 11th week of pregnancy, the detection of fetal pathologies is allowed. In Russia, two main standard protocols are defined, according to which data is decrypted.

These studies are conducted at 11-13 weeks of pregnancy and at 19-22 weeks. In order to more accurately decipher the data, you need to know the norms of fetal development at different stages of gestation.

At this time, a detailed examination of the collar zone of the fetus is carried out - the area between the tissues and the skin in the neck area. The thickness of the collar zone is abbreviated as TVP. Normally, TVP should not exceed 2.7 mm.

The nasal ossicle is another parameter that is being investigated at this time. Normally, the bone should be visualized.

Another indicator that is measured at this stage is KTR (coccyx-parietal size of the fetus).

For a kid at 11 - At week 13, the KTR is considered to be within 45-80 mm.

In addition to KTR, the doctor evaluates the biparietal and fronto-occipital dimensions of the fetus. The first is the distance from one temple of the head to another and is normally up to 28 mm. The second - the distance from the frontal to the occipital bone - normally does not exceed 31 mm.

* Percentile is a descriptive statistics term. The average value is indicated in the "50th percentile" column, in the "5th percentile" and "95th percentile" columns - the minimum and maximum allowable values, respectively.

Separately, the doctor evaluates the diameter of the fetal egg ...

... and calculates the heart rate (HR).

If the indicators do not correspond to the norm, the pregnant woman is recommended to undergo a consultation with a geneticist and an additional examination.

Second fetal screening

The norms of fetal development in the second trimester are shown in the table:

* Percentile is a descriptive statistics term. The average value is indicated in the "50th percentile" column, in the "5th percentile" and "95th percentile" columns - the minimum and maximum allowable values, respectively.

If there are any changes in these indicators, deviations in the development of the child in the womb can be assumed. By the way, during the second screening, the fetus is seen much better than during the first one, so the doctor can judge not only genetic abnormalities, but also other defects (they are recorded separately in the examination protocol).

As part of the third screening, such baby parameters as height, weight, biparietal head size, hip and chest length are evaluated. The norms of the listed parameters are described in the table above. Below are the normal indicators of BDP and LZR.

* Percentile is a descriptive statistics term. The average value is indicated in the "50th percentile" column, in the "5th percentile" and "95th percentile" columns - the minimum and maximum allowable values, respectively.

During the 3rd screening, the doctor evaluates the condition of the placenta, its degree of maturity and thickness. The placenta is the link between a mother and her baby. It remains for the entire duration of pregnancy. It exists in order to nourish the child with the necessary nutrients.

IAI norms (amniotic fluid index)

Fetal size by week of pregnancy

Each trimester has its own research and measurements. The interpretation of ultrasound indicators helps to establish the size of the child at the time of its development.

Below is a table of the size and weight of the fetus by week. It is worth saying that the readings are average, may differ from reality. This is especially true in the last months of pregnancy.

A newborn can be born with a weight of 2300 grams, or it can be born with a weight of 4500 grams. And in fact, and in another case, he can be absolutely healthy.

Term in weeks	Height in cm	Weight in g
	6-9	11-16
	9-11	16-21
	10-12	20-30
	12-14	30-50
	14-16	50-75
	16-18	75-115
	18-20	115-160
	20-22	160-215
	22-24	215-270
	24-26	270-350
	26-28	350-410
	28-30	410-500
	30-32	500-600
	32-34	600-750
	34-36	750-850
	36-37,5	850-1000
	37-39,5	1000-1200
	38-40	1200-1350
	39-40	1350-1500
	40-41	1500-1650
	41-42,5	1650-1800
	43-44,5	1800-1950
	44,5-45	1950-2100
	44,5-46	2100-2250
	46-46,5	2250-2500
	46,5-48	2500-2600
	48-49	2600-2800
	49-50	2800-3000
	50-51	3000-3200
	51-54	3200-3500

Ultrasound examination of the placenta

Ultrasound of the placenta determines its size, echostructure, development.

When the placenta may be hyperthick:

at detachment;

with Rhesus conflict;

with dropsy of the embryo;

mild thickening may occur in women with diabetes mellitus;

if in the process of bearing a pregnant woman suffered an infectious disease.

The placenta has the same functions as the human body - it tends to be born, mature and fade. All these moments are absolutely natural. But if it happens, it is a pathology.

Exists 3 degrees of maturity of the placenta:

Idegree of maturity. Until the 30th week of pregnancy, the placenta is at the zero degree of maturity. At this time, it increases in size, nourishing the baby with all the useful elements. The structure is normally homogeneous, smooth. After 30 weeks, specks and waves may appear on the placenta, which indicate the beginning of the maturation of the placenta. If the appearance of these signs is detected earlier, then this process is called "premature aging of the placenta." In some cases, women are prescribed medication. The first degree should last up to 34 weeks.

IIdegree of maturity. This degree comes from 34 to 37 weeks. It already looks more prominent, wavy, the ultrasound shows an echostructure with speckles. If the second degree is indicated earlier than 34 weeks, then more detailed diagnostics and fetal CTG will need to be performed. All tests as a whole will show if there are any fetal pathologies. If the child suffers from hypoxia, outpatient treatment may be prescribed.

IIIdegree of maturity. This degree is established already at full-term pregnancy. The placenta is preparing for childbirth and its functions are reduced, its natural aging occurs. There are large waves and salt deposits all over the surface.

If the placenta does not correspond to its term, then there is a risk of premature birth.

Ultrasound of the umbilical cord of the fetus

An umbilical cord passes between the placenta and the fetus, which connects them together. Ultrasound examination determines the number of vessels in the umbilical cord, their condition, structure.

The umbilical cord has two arteries and one vein that feed the fetus. The vein saturates the fetus with oxygen, and the arteries serve as the output of processed products.

The length of the umbilical cord should normally be at least 40 cm.

Ultrasound allows you to see the entanglement of the umbilical cord, if any. Establishment of entanglement is not yet a reason for a caesarean section.

Ultrasound examination of amniotic fluid

In the process of ultrasound, the amniotic index is calculated, which indicates the amount of water. The index is measured according to a certain scheme:

the uterus is divided into two perpendicular strips, one goes along the navel line, the other longitudinally;

in each sector, measurements of the free distance between the fetus and the wall of the uterus are made;

indicators are summed up.

Normal values ​​​​at week 28 will be AI readings of 12-20 cm. An increase in the value may indicate polyhydramnios, a decrease in indicators, respectively, of oligohydramnios.

* Percentile is a descriptive statistics term. The average value is indicated in the "50th percentile" column, in the remaining columns - the minimum and maximum allowable values, respectively.

In any case, this or that deviation indicates violations in the blood supply to the placenta.

Ultrasound of the uterus during pregnancy. The size of the uterus by week of pregnancy

When conducting an ultrasound of the uterus, its size is measured, its appearance is examined for the presence of myomatous nodes, muscle tone, and the thickness of the walls of the uterus is measured.

Before pregnancy, the thickness of the walls of the uterus is 4-5 cm, by the end of pregnancy, the uterus is stretched, its walls become thinner and are approximately 0.5-2 cm.

The normal length of the cervix is ​​3.5-4.5 cm.

Marianna Artemova, obstetrician-gynecologist, specially for website

Expectant mothers in the process of bearing a baby have to undergo a large number of examinations, including fetometry using ultrasound. This is one of the few non-traumatic procedures that can provide reliable information about the condition and development of the child throughout pregnancy.

Fetometry of the fetus, as a method, is the determination of the size of the baby by means of ultrasound scanning and the comparison of the data obtained with the existing standards. This information allows the attending physician to judge the occurrence of developmental anomalies or the normal process of gestation.

If there are difficulties with establishing the term of conception for the last menstruation, fetometry of the fetus allows you to determine it with an accuracy of 4 days. Therefore, we can say that this method is in demand in the early diagnosis of intrauterine development disorders and specifying the timing of pregnancy. All norms of fetal fetometry indicators are brought to the world standards of medicine and are indicated in tables with average statistical data.

Periods of passing a fetometric study

Ultrasound examinations to diagnose the development of the baby are usually timed to coincide with the 12th, 20th and 32nd weeks of pregnancy. There is one diagnostic procedure for each trimester.

The decision about the time of ultrasound and fetometry is made by the doctor. This is affected by:

• general condition of the expectant mother;
• the emergence of suspicions of a violation of the intrauterine development of the child;
• established dates for fetometry of the fetus.

Thanks to ultrasound, it became possible not only to evaluate the main characteristics of the fetus (calculate the weight of the fetus by ultrasound, its height, chest and head circumference) and correlate them with the average indicators for weeks of pregnancy, but also to identify the functional state of the internal organs of the child, determine its gender.

Thanks to modern ultrasound diagnostics, the doctor can not only compare fetometric data with the norm, but also evaluate the development of internal organs and determine the sex of the child.

Key characteristics of the fetometric study

The leading criteria for fetometry of the fetus are:

• KTP (coccyx-parietal size);
• BDP (biparietal head size);
• OG (chest circumference);
• coolant (abdominal circumference);
• DB (length of the thigh bone).

Table with average fetometry values ​​by week of pregnancy:

A week	BPR, mm	LZR, mm	coolant, mm	DBK, mm	Weight, gr	Height, cm
13	24	-	69	9	31	10
14	27	-	78	13	52	12,3
15	31	39	90	17	77	14,2
16	34	45	102	21	118	16,4
17	38	50	112	25	160	18
18	43	53	124	30	217	20,3
19	47	57	134	33	270	22,1
20	50	62	144	35	345	24,1
21	53	65	157	37	416	25,9
22	57	69	169	40	506	27,8
23	60	72	181	42	607	29,7
24	63	76	193	45	733	31,2
25	66	79	206	48	844	32,4
26	69	83	217	49	969	33,9
27	73	87	229	52	1135	35,5
28	76	89	241	55	1319	37,2
29	78	92	253	58	1482	38,6
30	81	95	264	60	1636	39,9
31	83	97	274	62	1779	41,1
32	85	100	286	63	1930	42,3
33	86	102	296	65	2088	43,6
34	88	104	306	67	2248	44,5
35	89	106	315	69	2414	45,4
36	91	108	323	71	2612	46,6
37	93	109	330	73	2820	47,9
38	94	110	336	74	2992	49
39	95	112	342	75	3170	50,2
40	96	116	347	76	3373	51,3

Additionally, the following ultrasound indicators can also be determined:

• fetal head circumference;
• fronto-occipital size;
• leg bone length;
• tibia length;
• foot length;
• the length of the bones of the shoulder and forearm;
• interhemispheric size of the cerebellum (MRM);
• heart diameter.

Nasal bridge development indicators are very important for assessing the development of the child in the framework of detecting chromosomal diseases and birth defects.

KTP as a characteristic of the physical development of the fetus

Deadline, weeks + day	10 weeks	+ 1 day	+ 2 days	+ 3 days	+ 4 days	+ 5 days	+ 6 days
KTR, mm	31	33	34	35	37	39	41
Deadline, weeks + day	11 weeks	+ 1 day	+ 2 days	+ 3 days	+ 4 days	+ 5 days	+ 6 days
KTR, mm	42	43	44	45	47	48	49
Deadline, weeks + day	12 weeks	+ 1 day	+ 2 days	+ 3 days	+ 4 days	+ 5 days	+ 6 days
KTR, mm	51	53	55	57	59	61	62
Deadline, weeks + day	13 weeks	+ 1 day	+ 2 days	+ 3 days	+ 4 days	+ 5 days	+ 6 days
KTR, mm	63	65	66	68	70	72	74

Variants of the norm include an increase in CTE by one to two weeks. If the Rh conflict, neoplasms and diabetes of the mother are excluded, then such an increase in the size of the baby may indicate that the child will be born large, with a weight of 4 kg or more.

In this case, it is necessary to use with caution medications that affect metabolism, including complex vitamins. Such drugs can lead to the birth of a very large child from 5 kg.

The reasons that can lead to a decrease in CTE can be both normal variants and a sign of severe pathology.

To the norm options includes the possibility of later fertilization due to the timing of ovulation. As you can see, the time of conception will be somewhat later than calculated in accordance with the last day of menstruation. In this situation, you just need to repeat the ultrasound in a week.

Causes of a pathological nature:

1. Frozen pregnancy and death of the embryo. This situation requires immediate intervention and medical assistance, because. can cause bleeding, impaired reproductive functions of the female body, toxic shock and death of the mother. This pathology can be excluded if the heartbeat of the unborn child is determined.
2. Lack of hormones (often progesterone) - requires confirmation with the help of additional research methods and hormone therapy (only a doctor can prescribe it!). Treatment is mandatory, because. hormonal deficiency can cause self-abortion.
3. Infections, including STIs, can be a factor that negatively affects the growth of the baby. In this situation, additional examinations are needed to identify the infectious agent. Then therapy should be carried out within the permitted time frame.
4. Genetic anomalies (syndromes: Down, Patau, Edwards). If such disorders are suspected, a genetic consultation and additional examinations are required. Serious genetic abnormalities usually lead to self-abortion.
5. Somatic diseases of the mother, including chronic diseases of the heart and thyroid gland. As a rule, they exert their influence at a later date. And yet it is impossible to exclude their influence from the first week of development of the embryo.
6. Pathology of the mucosa lining the uterus. Erosions, abortions, fibroids, violating the integrity of the mucous layer, prevent the fetal egg from properly gaining a foothold in the uterine wall and growing fully, which can cause self-abortion.

Insufficient KTR indicators, according to the table of standards, may indicate violations of the intrauterine development of the child, therefore, such a pregnancy needs additional examination

KTP is an important indicator of the development of the crumbs, but do not rush to interpret its value yourself, wait for the comments of the attending physician.

BDP as an indicator of the development of the fetal nervous system

The biparietal indicator, measured during fetometry, indirectly describes the development of the baby's nervous system and indicates the gestational age with a high degree of accuracy. In fact, BDP on ultrasound is the distance between the external visible boundaries of oppositely located parietal bones of the skull (right and left), which is determined along the line of the eyebrows. Often this parameter is measured together with the LZR indicator (frontal-occipital size) - the distance between the outer visible boundaries of the bones: occipital and frontal.

The characteristics of the BDP are used to determine the degree of safety for the mother and child of passing it through the birth canal during delivery. In the case when the value of BDP significantly exceeds the norm, operative delivery by caesarean section is indicated.

The BPR indicator in combination with the LZR indicator allows you to weekly evaluate the characteristics of the brain and the development of the baby's nervous system. A feature of biparietal characteristics is the slowdown in their growth with increasing gestational age.

At twelve weeks, the increase in BDP is about 4 mm per week, by the end of the gestation period, it barely reaches 1.3 mm. A competent interpretation of this indicator makes it possible with a high level of reliability to assess the growth and development of the baby throughout the entire period of gestation.

Slight fluctuations in the biparietal and fronto-occipital indicators may be options for the normal growth of the baby. For example, if the fetus is large (over 4 kg), then all parameters can be increased for a period of one to several weeks. Also, sometimes the head grows a little more / less than other organs, because the baby grows unevenly. In this situation, you need to repeat the ultrasound in a few weeks, perhaps the indicators will even out.

If the doctor diagnosed the patient with a large-fetal pregnancy, then the indicators of BPR and LZR can be naturally increased in accordance with the size and weight of the baby

A significant increase in these indicators can be an alarming symptom, indicating the development of neoplasms of bone or brain structures, the appearance of cerebral hernias and the accumulation of cerebrospinal fluid in the ventricles of the brain (hydrocephalus / dropsy of the brain):

• With the development of neoplasms and cerebral hernias, it is recommended to terminate the pregnancy. A fetus with such a pathology is usually not viable.
• Hydrocephalus, in most cases, occurs due to intrauterine infection. The infection must be treated with antibiotics without fail. If this treatment does not work, it is recommended to terminate the pregnancy. If there is no development of hydrocephalus, the fetus is usually allowed to be kept, but monitoring of its condition by ultrasound should be carried out constantly.

A decrease in the size of the fetal head may indicate an insufficient development of certain brain structures, or the absence of them. The absence of any brain structures is a strict indication for abortion, regardless of how long this pathology was detected.

After each ultrasound examination, the pregnant woman receives a special protocol containing important data on the development of the fetus. The main indicators include the biparietal size of the fetal head (abbreviated as BDP), which, unlike other indices, can “tell” the gestation period as accurately as possible. You will learn about what BPR is on ultrasound during pregnancy from today's material.

The concept of BDP

During the ultrasound procedure, doctors pay special attention to the baby's head. And this is not surprising, since the brain is one of the most important organs of the body, and its (brain) development has a direct impact on the state of the embryo. And BDP just determines the size of the head and, consequently, the degree of development of the brain.

This index denotes the "width" of the skull, so to speak, which is measured between the temples, that is, along the minor axis.

Note! Together with BPR, LZR is usually also measured - the distance between the forehead and the back of the head, that is, the measurement is performed along the major axis. Note that the values ​​of both indices with maximum accuracy can only be obtained between the 12th and 28th weeks of pregnancy.

The BDP index is important in determining the possibility of natural childbirth. If the circumference of the birth canal is less than the circumference of the baby's head, then doctors decide to resort to a caesarean section.

What is the BPR standard?

To evaluate this index by week, a special table was created, which indicates the norms of the BDP of the embryo, as well as permissible deviations.

BRGP (BDP) - biparietal head size. DB - thigh length. DHRK - diameter of the chest. Weight - in grams, height - in centimeters, other indicators in millimeters

BDP of the fetus exceeds the norm - what does this mean?

In some cases, the index exceeds the permissible norms. In this case, the attending physician is obliged to determine other parameters of the fetus (such as the circumference of the abdomen, the length of the hips, etc.) in order to make sure that there are no pathologies. And if the rest of the parameters exceed the norm for at least one or two weeks, then the expectant mother has a large fetus. But if these indicators are within the acceptable range, then it is likely that the child simply develops in leaps and bounds, and all parameters will soon level out.

As for significant deviations of BDP from the norm, they often indicate serious problems in development. For example, an increased index can be with a tumor of the cranial bones or the brain itself, as well as with hydrocephalus and cerebral hernia. In each of the listed cases (the only exception is hydrocephalus), women are advised to immediately terminate the pregnancy, since such pathologies are, unfortunately, incompatible with life. But hydrocephalus is treated with antibiotics or (if the treatment has not given any result) an abortion is performed.

Note! With too low BDP in the embryo, nothing good should be expected either - often this indicates an underdevelopment of the brain or the absence of certain of its components (right, left hemispheres, or both at once, cerebellum, etc.). In such cases, the fetus is aborted regardless of the gestational age.

In the last trimester of pregnancy, a low biparietal size indicates a delay in fetal development. This syndrome is treated with special drugs (such as actovegin, chimes, etc.), which stimulate blood flow in the uterine cavity and placenta.

Average values ​​of fetometry of the fetus

week of pregnancy	Height, mm (KTR - coccyx-parietal size)	Weight, g	Chest diameter, mm
11	6,8	11	20
12	8,2	19	24
13	10	31	24
14	12,3	52	26
15	14,2	77	28
16	16,4	118	34
17	18	160	38
18	20,3	217	41
19	22,1	270	44
20	24,1	345	48
21	25,9	416	50
22	27,8	506	53
23	29,7	607	56
24	31,2	733	59
25	32,4	844	62
26	33,9	969	64
27	35,5	1135	69
28	37,2	1319	73
29	38,6	1482	76
30	39,9	1636	79
31	41,1	1779	81
32	42,3	1930	83
33	43,6	2088	85
34	44,5	2248	88
35	45,4	2414	91
36	46,6	2612	94
37	47,9	2820	97
38	49	2992	99
39	50,2	3170	101
40	51,3	3373	103

Video - Fetal Anatomy Screening

Video - Ultrasound of the fetus at 19 weeks

Monitoring the development of the unborn child

Fetometry is an ultrasonic method for determining the size of the fetus, the use of which allows future parents to:

• make sure your child is developing properly;
• find out his gender in the early stages;
• enjoy the first smile of a child;
• capture his first movements.

Basic diagnostic parameters

With each ultrasound, the specialist issues a conclusion, which must indicate the following parameters of fetometry:

• KTR(coccyx-parietal size) - used in early pregnancy, when assessing a fetus with a size of 20-60 mm. When this parameter is changed, the variability is 3-5 days.
• BDP(biparietal size) - used to determine the duration of pregnancy in the second trimester. The accuracy of determining the term is 7-11 days.
• DB(measuring the length of the thigh) - the gestational age can also be determined by measuring the thigh bone. The accuracy of the deadline will vary within 2 weeks. DB is used if BDP cannot be satisfactorily derived.
• coolant(abdominal circumference) allows you to determine the main indicators of the development of the child. The measurement is carried out in a plane in which a short segment of the umbilical vein, fetal stomach, gallbladder, venous duct are visualized. This parameter is the most informative in assessing the growth of the fetus. But it should not be used for macrosomia, that is, when the estimated fetal weight already exceeds 4 kilograms.
• OG(chest volume) allows you to determine the gestational age at 14-22 weeks. The accuracy of the indicator varies within 3-4 days.

The simultaneous use of several indicators increases the percentage of accuracy of the gestational age. For up to 36 weeks, specialists are guided by coolant, BDP and DB. After 36 weeks, a combination of coolant, OG and DB is used. However, this approach needs to be individualized according to asymmetric fetal growth retardation.

Average values ​​of fetometry indicators

There are special tables that indicate the indicators of the norm. As a rule, a pregnant woman is prescribed an ultrasound examination in each trimester, this is in the 12th, 22nd and 32nd weeks. Consider the indicators of fetometry tables for these periods.

Table of indicators for trimesters
Trimester	KTR, mm	BPR, mm	dB, mm	coolant, mm	OG, mm

You can independently compare your child's measurements with the checklist, which shows the average height and weight, as well as the biparietal head size, hip and chest diameter, presented below.

Weekly average fetometry table
A week	Height, cm	Weight, g	BRG, mm	dB, mm	DGK, mm

You should not panic if the indicators in the conclusion do not match the parameters indicated in the table. It only shows average values. In each case, the physiological characteristics of the unborn child and his parents should be compared.

Algorithm for reading indicators

To determine the estimated date of delivery and the convenience of the doctor, it is advisable to indicate the obstetric gestational age. It is calculated based on the first day of the last menstrual cycle. Fetometry data should also be taken into account. But there are differences here.

• recalculation of the term, based on the 1st day of the last menstruation or the day of conception;
• recalculation of the term, based on the results of ultrasound examinations of the 1st or 2nd trimester;
• determination of the percentage level for DG, BPR, J;
• assessment of the probability of intrauterine growth retardation.

The need for a procedure

Ultrasound fetometry plays an important role in the diagnosis of malnutrition (intrauterine growth retardation). This syndrome manifests itself when the size of the fetus lags behind the size of the established period by more than two weeks.

The decision on the diagnosis is always made by the doctor. It should take into account the state of health of the pregnant woman, the functioning of the placenta, genetic factors, the standing of the bottom of the uterus, and so on. Most often, the causes of this pathology are the bad habits of the expectant mother, infections and chromosomal abnormalities in the child.

Today, this syndrome is treated on an outpatient basis and in a hospital. In particular, sanitation of foci of infection, correction of placental insufficiency, formation of a diet, treatment of complications during pregnancy are carried out.