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Atlas of Human Body Ultrasound Scanning_ Methods and Diagnostic Applications ( PDFDrive ).pdf
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13  Normal Pregnancy

475

 

 

1\ First Trimester Scanning

1.1\ Longitudinal Scanning

of Early Pregnant Uterus

1.1.1\ Scanning Method

Fig. 13.1  More than 5 weeks of gestation. Sagittal section of the uterus and the gestational sac are shown. Ut uterus, GS gestational sac, BL

bladder

GS

GS

Ut

BL

 

BL

Ut

476

YQ. Zhou et al.

 

 

The patient is maintained in the supine position, with full bladder and exposure of the lower abdomen. The probe should be placed longitudinally on the medioventral line above the pubic symphysis.

1.1.2\ Section Structures

Sagittal section of the uterus and sagittal section of the gestational sac.

1.1.3\ Measuring Method and Normal Reference Values

The longitudinal diameter and the anteroposterior diameter of uterus are measured in this section, as well as the longitudinal diameter and the anteroposterior diameter of the gestational sac. The normal reference values are shown in Table 13.1.

1.1.4\ Clinical Significance

Bilayer structure is an important character of the early gestational sac, which consisted of the inner layer of amnion and the outer layer of chorion, shown as two slightly strong echoic rings with a hypoechoic region between the two rings. The size, shape, and tension of the gestational sac should be observed also.

Table 13.1  Relationship between estimated average diameter of gestational sac (EAGS) and gestational age (GA)

EAGS (mm)

GA (weeks)

EAGS (mm)

GA (weeks)

10

5.0

36

8.8

 

 

 

 

11

5.2

37

8.9

 

 

 

 

12

5.3

38

9.0

13

5.5

39

9.2

14

5.6

40

9.3

 

 

 

 

15

5.8

41

9.5

 

 

 

 

16

5.9

42

9.6

17

6.0

43

9.7

18

6.2

44

9.9

 

 

 

 

19

6.3

45

10.0

 

 

 

 

20

6.5

46

10.2

21

6.6

47

10.3

22

6.8

48

10.5

 

 

 

 

23

6.9

49

10.6

 

 

 

 

24

7.0

50

10.7

25

7.2

51

10.9

26

7.3

52

11.0

27

7.5

53

11.2

 

 

 

 

28

7.6

54

11.3

29

7.8

55

11.5

30

7.9

56

11.6

31

8.0

57

11.7

 

 

 

 

32

8.2

58

11.9

33

8.3

59

12.0

34

8.5

60

12.2

35

8.6

 

 

 

 

 

 

Cited from Hellman LM, Kobayashi M, Fillisti L, et al. Growth and development of the human fetus prior to the twentieth week of gestation. Am J Obstet Gynecol, 1969,103(6):789–800

13  Normal Pregnancy

477

 

 

1.2\ Transverse Scanning of Early

Pregnant Uterus

Fig. 13.2  More than 5 weeks of gestation.

Transverse section of the uterus and the gestational sac are shown. UT uterus, GS gestational sac, BL bladder

BL

BL

Ut

GS

GS

Ut

478

YQ. Zhou et al.

 

 

1.2.1\ Scanning Method

The patient is maintained in the supine position, with full bladder and exposure of the lower abdomen. The probe should be placed transversely on the medioventral line above the pubic symphysis.

1.2.2\ Section Structures

Transverse section of the uterus and transverse section of the gestational sac.

1.2.3\ Measuring Method and Normal Reference Values

The transverse diameter of the uterus and the transverse diameter of the gestational sac are

measured in this section. The normal reference values are shown in Table 13.1.

1.2.4\ Clinical Significance

The size, shape, and tension of the gestational sac can be observed in this section, as well as the left and right adnexal regions including the corpus luteum and its size.

13  Normal Pregnancy

479

 

 

1.3\ Sagittal Scanning of an Early

Pregnant Uterus in 5–6 Weeks

of Gestation

Fig. 13.3  Early pregnant uterus at 5–6 weeks of gestation. Sagittal section of the uterus, the gestational sac, the fetal body bud, and the yolk sac are shown. BL bladder, GS gestational sac, YS yolk sac, EMB embryo bud

GS

YS

BL

EMB