Chapter 51: Sonography of the Second and Third Trimesters

anatomy scans should be done between ____ weeks.

18-22 weeks

____ capabilities facilitate evaluation of amniotic fluid volume, umbilical cord, and speciality evaluations of fetal heart and other aspects of fetal and maternal circulation.

doppler

____ equipment can record volume of targeted anatomic region.

three-dimensional

if there is concern of ____, won’t do TV scan to prevent infection.

ruptured membranes

practices that receive ultrasound accreditation from ______ or _____ have been show to improve compliance with published national standards and guidelines.

American College of Radiology or American Institute of Ultrasound in Medicine

sonographer should initially determine ____ in relationship to ____.

position of fetus, position of mother

what should be viewed at the beginning of each study to ensure that fetus is alive?

cardiac activity

fetal presentation = head down over ML

vertex (cephalic)

fetal presentation = head or butt is off to the right or left

oblique

fetal presentation = will see abdomen at the ML and the head will be off to the right or left

transverse

doctor manipulates the baby to be vertex (cephalic) from a breech presentation

external version/external cephalic version

incomplete breech where one foot is out first

footling

incomplete breech where both feet come out first

double footling

breech position with the feet at the head; baby will have hip flexor problems if baby remains in this position for awhile

frank breech

right and left sides of fetus need to be conceptualized to ensure ____.

normal situs

if fetus is in vertex position with fetal spine toward maternal right side, ___ side of the fetus is down and ___ side is up.

right, left

cranial bones ossify by the ___.

12th week

the cranium appears as a ___ at the highest levels.

circle

the cranium appears as a(n) ____ at ventricular, peduncular, basal levels.

oval

at the level of a BPD measurement, the cranium should appear with a __ shape.

oval

what may distort normal shape of the skull?

extracranial masses, CNS anomalies, skeletal pathology, or fetal death

soft tissue piece connecting the right and left sides of the brain, located above the CSP

corpus callosum

the ____ sits between the thalami.

third ventricle

normal fetal brain parenchyma appears ____.

hypoechoic

the sulcus and gyrus appear more ____ than the normal brain parenchyma.

echogenic

branches of ___ run within midline sulci and may be seen to pulsate within echogenic structures.

anterior cerebral artery (usually the MCA at the circle of willis)

standard OB examination of the cranium guidelines require the sonographer to image and record…

cerebellum, choroid plexus, cisterna magna, lateral cerebral ventricles, midline falx, CSP

what does the fetal ventricular system consist of?

two paired lateral ventricles, midline third ventricle, and fourth ventricle adjacent to cerebllum

the ventricular system contains ____, which coats the brain and spinal cord.

CSF

what produces CSF?

choroid plexus

dilated ventricular system is called ____ or ____.

ventriculomegaly or hydrocephalus

mild ventriculomegaly measures ___.

higher than 10 mm

how should the ventricular cavity be seen sonographically?

sonolucent space filled with choroid plexus

the inferior portion of the lateral ventricles connects with…

temporal (inferior) and posterior horns

choroid plexus are ____ shaped.

tear-shaped

what is the most inferior portion of the choroid plexus body?

glomus

the most inferior portion of the choroid plexus body, or the glomus, marks the site of ____.

atrium

the anterior horn of the lateral ventricle is ____ and ____ to the CSP.

lateral and anterior

what fills the lateral ventricle in normal pregnancy?

choroid plexus

if the glomus appears to float or dangle with cavity, it is a sign of ____.

ventriculomegaly

the normal measurement at the atrium level of the lateral ventricle is ____.

6.5 mm

if the atrium of the lateral ventricle measures ____, it warrants serial imaging and further evaluation.

greater than 10 mm

moving the transducer slightly inferior to the ventricular atrium identifies the area of the _____.

thalami

the widest transverse diameter of the skull is the proper level to make what/which measurement(s)?

BPD and HC

small portion of the brain that is located up under the cerebellum

vermis

slit-like hypoechoic region that is located between the thalami

third ventricle

echogenic piece in front of the CSP that connects the left and right hemispheres of the brain

corpus callosum

you shouldn’t see anything between the thalami, but if you do, it is abnormal and likely a dilated ____.

third ventricle

echogenic piece that surrounds/covers the lateral ventricle

corpus callosum

as transducer is moved toward base of the skull (inferior), you will see ____.

posterior fossa

the cerebellar measurement should correspond with ___.

gestational age

peanut-shaped, located right under the thalami

cerebellum

a nuchal fold measurement of _____ gives confidence nothing is wrong.

less than 5 mm

nuchal fold is usually not measured after what gestational age?

22+6

the cisterna magna should measure ___.

less than 11 mm

T/F echogenic striations/linear echoes seen within the cisterna magna is a normal finding.

true

the echogenic structures that may be seen within the cisterna magna represent _____ that attach falx cerebelli.

dural folds

normal cisterna magna measures ____.

3-11 mm

the average size of the cisterna magna is ___.

5-6 mm

nuchal fold thickness is measured in which trimester?

second

in the second trimester, thickness of nuchal skin fold is measured in the plane containing what anatomic landmarks?

CSP, cerebellum, and cisterna magna

a thickened nuchal fold corresponds to potential for ___.

aneuploidy

values of skin thickness of ____ up to 20 weeks gestational age is normal.

5 mm or less

visualization of the face is heavily dependent on…

fetal positioning, adequate amounts of amniotic fluid, excellent acoustic windows

when scanning inferior to or below the cerebellar plane, ____ may be visualized.

orbits

when imaging orbits, it is important to note…

both orbits are present and spacing between both orbits appears normal

condition in which eyes are missing

anophthalmia

condition in which fetal eyes are fused or closely spaced

hypotelorism

condition in which fetal eye orbits are abnormally widened

hypertelorism

echogenic structure seen within orbits

lens

if the chin is recessed too far back =

micronagthia

if the forehead is bulging out =

frontal bossing

frontal bossing corresponds to ___.

skeletal dysplasia

when getting the profile, what should be seen/evaluated?

normal forehead, nasal bone, tip of the nose, top/bottom lip, chin with fluid underneath

appears as a bright echo parallel to the echogenic skin interface in the superior aspect of the nose

nasal bone

small/absent nasal bone in african americans can be considered normal. however in others, it is concern for…

aneuploidy, specifically trisomy 21

the measurement of the nasal one should correspond to ___.

gestational age

if the fetal tongue continues to stick out and doesn’t recess back in.. it is called ___.

macroglossia

macroglossia corresponds with ____ and ___.

trisomy 21 and beckwith wiedemann syndrome

continuation of soft tissue of top lip helps to rule out ___.

cleft lip/cleft palate

white striations that can be seen coming off the head represents ___.

hair

what are the 3 ossification points in each vertebra?

transverse process, pedicle, and lamina

the normal fetal spine tapers near the ____ and widens near the ___.

sacrum, base of skull

the vertebral column has a double line appearance referred to as “___.”

railway sign

the railway sign seen is generated by…

echoes from posterior and anterior laminae and spinal cord

the MCA is measured to determine…

brain sparing effects

if the MCA has vey high velocities =

anemia

the ____ is the last thing to lose flow

brain

the closer we are to a ___ angle, the more accurate the peak velocity will be.

0°

what serve as lateral borders for the heart and are helpful in assessing relationship and position of the heart in the chest?

lungs

____ of the lung will displace the heart right or left or superior or inferior.

hyper or hypoplasia

what is the very last thing to mature in development?

lungs

what steroid is given to mother’s who are delivering early to improve outcomes of premature deliveries?

betamethasone

fetal breathing movements are observed at the level of…

the diaphragm/thorax

how should the lungs appear sonographically?

homogeneous

the lungs should appear homogeneous and located ____ to the heart and ____ to the diaphragm.

lateral; superior

surrounds and protects the thoracic cavity

ribs

the scapula should be seen _____ to the ribs.

lateral

why does the heart lie more transversely in the fetus than in an adult?

because the lungs are not inflated

in the TRV view, the apex of the heart is directed how many degrees towards the left anterior chest?

45°