Chapter 51- Sonography Of 2nd/3rd Trimesters Flashcards by Ty Christensen

Anatomy is accurately assessed at how many weeks gestation?

18 weeks

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First two things to look at during examination:

Fetal position and cardiac activity

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Fetal positions change less frequently after ___

34 weeks

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Fetal lie is described in relation to

Maternal long axis

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Fetus head down:

Vertex/cephalic

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Fetal head up:

Breech

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Thigh flexed at hips and lower legs extended in front of the body & up in front of the head

Frank breech

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Both hip and lower extremities are found in the lower pelvis…needs to be delivered by c-section

Complete breech

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Hips extended and one or both feet are the presenting parts closest to the cervix

Footling breach

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Imaging of the brain and skull is done in a _____ plane

Transverse

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Normal brain parenchyma appears

Hypoechoic

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The fetal brain becomes more difficult to visualize as pregnancy progresses because

Calcification of the skull

Fetal head moves deeper in the maternal pelvis

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Superior cranial structures include

Choroid plexus

- Lateral ventricles

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Produces cerebrospinal fluid

Choroid plexus

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Echogenic been like/tear shaped structures

Choroid plexus

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Occasionally small cyst can be seen in the choroid plexus in normal pregnancy. This can also be associated with

Trisomy 18

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Cerebrospinal fluid can become trapped during early development resulting in the formation of

CP cyst(s)

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The lateral ventricle should measure

Less than 10 mm

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The lateral ventricles are measured at the level of the ___ in a transverse plane

Atria

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Midline cranial structures

Cavum septum pellucidum(CSP)
Midline falx
Thalamus
Corpus callosum

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Midline hyperechoic line that divides the cranial structures into right and left

Midline falx

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Straddles the midline falx, looks like a heart or arrowhead

Thalami

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Between the thalami lies the cavity of the

3rd ventricle

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Boxed shaped echogenic lines straddling the midline falx

Cavum Septum Pellucidum

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The CSP is ___ to the thalamus

Hypoechoic structure seen in the transverse plane as the band of tissue between the frontal tissue between the frontal ventricular horns

Corpus callosum

Inferior cranial structures

- Cerebral peduncles - Circle of Willis - Cerebellum - Cisterna Magna - Nuchal fold

Appears as a highly pulsatile triangular region.

Circle of Willis

Cerebellum is ____ shaped

Peanut

Located directly behind the cerebellum, filled with cerebrospinal fluid

Cisterna magna

A normal cisterna magna measures

3-11mm average— 5-6

In the second trimester the nuchal fold is measured in a plane containing the

Cerebellum and Cisterna Magna(CM)

At 20 weeks or less, a measurement of _____ is normal

5mm or less

Nuchal fold measurement is unreliable after

20 weeks

Fetuses with thickened Nuchal skin are at risk for

Aneuploidy

The fetal ventricular system contains what substance?

CSF

CSF coats the:

Brain and spinal cord

The fetal ventricular system flow:

1. lateral ventricles 2. foramen Monroe 3. 3rd ventricle(between thalami) 4. aqueduct of Sylvius 5. 4th ventricle 6. foramen of Magendi(medial), foramen of Luscha(lateral) 7. Cerebral & subarachnoid spaces 8. Venous system

The most common type of fetal hydrocephaly

Aqueduct stenosis at the level of the aqueduct of sylvius

Aqueduct stenosis at the level of the aqueduct of sylvius will result in

Excess fluid in the lateral and 3rd ventricles

Inner Orbital Distance(IOD) measurement should be made from

Medial border to opposite medial border

Outer Orbital Distance(OOD) is measured from the

Lateral border to opposite lateral border

Outpouching on brain

Anterior cephaloceles

Small chin:

Micrognathia

Abnormal forehead slope-more prominent than normal

Frontal bossing

Small/absent nasal bone is risk factor for

Aneuoploidy

Large tongue that persistently protrudes outside of the mouth:

Macroglossia

In LONG, the double lines of the spine is referred to as:

Train tracks

In TRANS, the spine will visualize

3 ossification points

Fetal lung tissue appears ____ as pregnancy progresses

More echogenic than the liver

Standard heart exam requires a ____

- 4 chamber view | - views of the right/left outflow tracts

The heart lies more ______ in the fetus than the adult because ___

Transverse Lungs aren’t inflated

The apex of the heart is directed toward ___

The left anterior chest

Echogenic structure that appears within a cardiac chamber and persists despite changing transducer positions is termed

Echogenic Intracardiac focus (EIF)

Oxygen/nutrient rich blood is carried to the fetal circulation via the

Umbilical vein

This structure when it doesn’t close during development is called a “hole in the heart”

Foramen ovale

There are three circulatory shunts in the fetal heart what purpose do they serve

Protect the lungs from circulatory overload

What are the three circulatory shunt in the fetal heart

1. Ductus Venosus 2. Foramen ovale 3. Ductus arteriosis

Lies inferior to the heart and lungs and superior to the liver spleen and stomach

Diaphragm

The muscle that separates the thorax and abdomen

The diaphragm

What liver lobe is bigger in fetus?

Left

Why is the left liver lobe bigger?

Large quantities of oxygenated blood flows through the ductus venosus to the left lobe

The stomach becomes apparent as early as the ____

11th week

Full stomach should be seen in all fetus is beyond the

16th week

The echogenicity of the bowel is typically _____ than the liver

More echogenic

If fetal bowel is as echogenic as the bone it is termed

Hyperechoic bowel

Hyperechoic Bowel is associated with increased risk for

Aneuploidy

Kidneys can be seen as early as

13 weeks

Abnormal renal pelvis measurements before 20 weeks:

5mm

Abnormal renal pelvis measurements between 20-30 weeks

Greater than 8mm

Abnormal renal pelvis measurements beyond 30 weeks

Greater than 10mm

Fetus generally voids (urine) at least ____

Once an hour

Gender may be appreciated as early as

12 weeks

Female gender best visualized in :

Transverse

Female sign:

Hamburger sign

Fetal labia may appear swollen and edematous due to ___

Circulating maternal hormones

Scrotum/penis are fairly easily recognized in ____

Either plane

Fluid seen around the testicles, is a common finding.

Hydrocele

Male sign:

Turtle sign

Short femur/humerus is associated with increased risk for

Aneuploidy

Hands and fingers should be noted whether they ____

Are clenched or open/close normally

When persistent and abnormal flexion of the ankle is seen, _____ should be expected

Club feet

___________ is required to measure the cervix

Transvaginal

Normal cervix measures _____ in pregnancy

3cm or longer

cervix is shortened, or the internal os appears to have a V or you shape is termed ____

Funneling

You may be able to differentiate the right from left sides by identifying an atomic landmarks such as

Stomach, heart, and spine

Stomach is on the

Left

Heart points to the

Left

Spine is on the

Back