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

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4.10\ Color Doppler Flow Image

of the Cord Around Neck in

Transverse Section of the

Fetal Neck

Fig. 13.24  Transverse section of the fetal neck. Color Doppler flow signals are shown around the neck

Blood flow signal of the umbilical cord

The colorized structure in the color sampling frame is the cord around the neck.

4.10.1\ Scanning Method

The probe is moved down to find the transverse section of fetal neck after the head is detected.

4.10.2\ Section Structures

Fetal neck skin and transverse section of the cervical vertebra are shown.

4.10.3\ Clinical Significance

In normal second and third trimester, there is an anechoic region between the fetal neck and the uterine wall, which is clear in image, referring to amniotic fluid. When there was a cord around the neck, umbilical echoes would be shown as black and white circles around fetal neck in gray-scale ultrasonography, and signals of umbilical arteries and veins would be detected by color Doppler flow imaging.

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4.11\ Four-Chamber View

of the Fetal Heart

Fig. 13.25  Fourchamber view of the fetal heart in gray-­scale image. Two ventricles and two atriums are shown. LV left ventricle, RV right ventricle, LA left atrium, RA right atrium

LV

LA

YQ. Zhou et al.

RV

RA

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4.12\ Color Doppler Flow

Image of Fetal Cardiac

Four-Chamber View

Fig. 13.26  Fourchamber view of the fetal heart with color Doppler flow image. The red blood flows represent the blood flows from the atriums to the ventricles (toward the probe). LV left ventricle, RV right ventricle, LA left atrium, RA right atrium

RV

LV

RA

LA

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YQ. Zhou et al.

 

 

4.12.1\ Scanning Method

Thoracic transverse section can be found through four-chamber view of fetal heart, which is perpendicular to fetal long axis.

4.12.2\ Section Structures

The main structures shown in the image are (1) the left and right atriums, primary atrial septum, patent foramen valve that opens to the left atrium, and two open pulmonary veins flowing into the left atrium; (2) the left and right ventricles, musculus papillaris and tendineae in the right ventricle, and ventricular septum; (3) the endocardial cushion cross and left and right atrioventricular valves; (4) bilateral blood flows passing through atrioventricular valves which are symmetrical and consistent in direction, brightness, and width (Figs. 13.25 and 13.26).

4.12.3\ Measuring Method

The ventricular inner diameters (including transverse diameter and anteroposterior diameter) are measured at end-diastolic phase of the ventricle,

while the atrial inner diameters (including transverse diameter and anteroposterior diameter) are measured at end-diastolic phase of the atrium. Fetal heart rate can be measured by Doppler ultrasound or M-mode ultrasonography.

4.12.4\ Clinical Significance

Four-chamber view is one of the basic sections of fetal anatomy screening, valuable in detecting approximately 50–60% congenital heart diseases, including left or right heart dysplasia, atrioventricular canal, Ebstein anomaly, dextrocardia, etc. Doppler or M-mode ultrasound is used in measuring heart rate and in diagnosing tachycardia, bradycardia, and arrhythmia.

4.12.5\ Normal Reference Values

Normal values of the ventricles and atriums change with the growth of gestational weeks.

13  Normal Pregnancy

4.13\ Left Ventricle Outflow Tract

View of the Fetal Heart

Fig. 13.27  Left ventricle outflow tract view of the fetal heart is shown. LV left ventricle, AO aorta, LA left atrium, RV right ventricle

LV

LA

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RV

Ao