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

495

 

 

3.1.2\ Breech Presentation of Fetus

Fig. 13.12  The fetus is in breech presentation of longitudinal lie. FH fetal head, FB fetal body, AF amniotic fluid

AF

FH

FB

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3.1.3\ Scanning Methods

The probe is moved on the mother’s abdomen surface longitudinally and transversely in turn, to find the relationship between the fetal long axis and the mother’s long axis. When the fetal long axis is in the same direction as the mother’s, the fetus is in a longitudinal lie (Figs. 13.11 and 13.12). When the fetal long axis and the mother’s is perpendicular, the fetus is in a transverse lie.

3.1.4\ Section Structures

The left side of the image is the head side of the mother, and the right side of the image is the foot

side of the mother. When the fetal long axis is in the same direction as the mother’s, the fetus is in a longitudinal lie. In cephalic presentation, fetal head lies toward the mother’s foot side. In breech presentation, fetal head lies toward the mother’s head side.

3.1.5\ Clinical Significance

Determination of fetal lie is helpful in fetal morphological examination and obstetrical management.

13  Normal Pregnancy

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3.2\ Judgment of Fetal Position

and Presentation

3.2.1\ Left Occipitoanterior (LOA)

Position of Fetus

Fig. 13.13  The fetus is in left occipitoanterior (LOA) position of occipital presentation.

FRONTAL B frontal bone, SP septum pellucidum, THA thalamus, LLCV left lateral cerebral ventricle, OC occipital bone

TH

OC

S.P.

FRONT ALB

LLCV

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3.2.2\ Right Occipitoanterior (ROA)

Position of Fetus

Fig. 13.14  The fetus is in right occipitoanterior (ROA) position of occipital presentation.

FRONTAL B frontal bone, S.P. septum pellucidum, THA thalamus, RLCV right lateral cerebral ventricle, OC occipital bone

OC

RLCV

T

FRONTAL B

CSP

3.2.3\ Scanning Method

The probe is placed above the pubic symphysis to detect the fetal head. The fetal presentation is cephalic when the fetal lie is also longitudinal. In cephalic presentation, if the fetal cranium enters the pelvis first, it is called “cephalic presentation.” Occipital bone is the indication point of cephalic presentation, so the fetal position is “left occipitoanterior” when the occipital bone is at the left anterior direction of the mother’s pelvis, and fetal position is “right occipitoanterior” when the occipital bone is at the right anterior direction of the mother’s pelvic cavity.

3.2.4\ Section Structures

In left occipitoanterior presentation, the middle line of the thalamus section is deflected a little upward in the left direction; fetal occipital bone is pointed to the left anterior side of the mother (Fig. 13.13). In right occipitoanterior presentation, the middle line of the thalamus section is deflected a little upward in the right direction; fetal occipital bone is pointed to the right anterior side of mother (Fig. 13.14).

3.2.5\ Clinical Significance

Determination of fetal position and presentation is helpful in fetal morphological examination and obstetrical management.

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4\ Observation of Fetal

Anatomy Structures

and Main Measurements

Observing fetal anatomy structures in some specific sections and measuring some specific fetal dimensions are important methods to evaluate fetal growth and development. Ultrasound is used to estimate fetal size, gestational age, and fetal

body weight and is of important clinical value. Some fetal anomalies or chromosomal abnormalities may be shown as abnormal dimensions.

4.1\ Scanning of the Lateral

Cerebral Ventricle at Fetal

Thalamus Plane

Fig. 13.15  Section and measuring of the posterior horn of lateral cerebral ventricle at thalamus section. The fetus is in breech presentation. FRONTAL B frontal bone, S.P. septum pellucidum, THA thalamus, LV left lateral cerebral ventricle, OC occipital bone, D1 width of left lateral cerebral ventricle which is 4.2 mm

 

T

OC

FRONTAL B

S.P.

 

LV