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Atlas of Human Body Ultrasound Scanning_ Methods and Diagnostic Applications ( PDFDrive ).pdf
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1.8\ Coronary Scanning at 10–12

Weeks of Gestation

Fig. 13.8  Coronary section of the fetal trunk and long axis view of the fetus spine are shown at 10–12 weeks of gestation. FH fetal

head, S fetal spine

FH

S

FH

S

1.8.1\ Scanning Method

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

1.8.2\ Section Structures

Sagittal section of uterus and coronal section of the fetus with the fetal head, spine, thorax, abdomen, and limbs are shown.

1.8.3\ Measuring Method

In this section, whether a hyperechoic beaded spine is lined up or not can be observed.

1.8.4\ Clinical Significance

Spine structures could be shown clearly at 10–12 weeks of gestation. The spine alignment is observed mainly in both this section and the sagittal section, and the intact of spine, especially sacrococcyx, is investigated. The main fetal organs have formed during this gestational period.

13  Normal Pregnancy

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1.9\ Sagittal Scanning of the Fetus

in First Trimester

Fig. 13.9  Middle sagittal section of the fetus in 11 weeks to13 weeks and 6 days. The whole fetal length (crown-rump length) is measured. CRL crown-rump length, GA gestational age

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1.9.1\ Scanning Method

Move the probe until the fetal long axis median sagittal section is seen.

1.9.2\ Section Structures

Fetal head, profile, and trunk are shown in this section, with nasal bone recognized at the same time.

1.9.3\ Measuring Method

The largest CRL is measured from fetal top to tail, when the fetus is in its natural curve, without over-flexion or over-extension.

1.9.4\ Clinical Significance

CRL is the most accurate index for estimating fetal age in first trimester, and is a best indicator used from 7 to 10 weeks of gestation, when the fetal crown-rump border is more clear and there are less fetal movements. Meanwhile, the correct CRL image is an essential condition for accurate measuring of nuchal translucency (NT), which is measured only when CRL is between 45 and 84 mm.

1.9.5\ Normal Reference Values

The normal reference value of CRL changes with the gestational age.