Ch. 20-Fetal Age and Size in 2&3 Tri's

Minimum distance between two bright echoes along the path of the US beam which is half the spatial pulse length

axial resolution

Measurement from the frontal to the occipital obtained at the same level as the BPD

occipito-frontal diameter (OFD)

Precision rate of the probability of disease

predictive value

Ratio of the BPD to the OFD

cephalic index (CI)

Fetus over 4,000g (8 lbs, 13 oz)

macrosomia

The fetal expected birth date is known as the EDC or:

• GA

• EDD

• GA

• LMP

EDD

The most accurate fetal measurement in the second and third trimesters can be obtained from:

• the BPD

• the AC and FL

• the HC

• multiple parameters

multiple parameters

Which phase of pregnancy provides the most accurate dating?

• early embryo measurements

• early second trimester, 18 to 18 weeks

• late second trimester, 25 to 26 weeks

• early third trimester, 28 to 29 weeks

early embryo measurements

The preferred measurement method for fetal growth is:

• one single measurement

• BPD, FL, AC, HL, HC

• average of multiple measurements, three or more

• HC, AC, FL

average of multiple measurements, three or more

The normal duration of pregnancy is:

• 40 weeks from ovulation

• 40 weeks from the LMP

• conception date plus 40 weeks

• GA plus 4 weeks

40 weeks from the LMP

Hadlock and coworkers and OTT determined the accurate indicator of fetal age is determined by:

• single fetal parameter average age

• FPA

• multiple fetal parameters average age

• femoral diaphysis length

multiple fetal parameters average age

The earliest successful BPD measurement can usually be secured at week:

• 10

• 12

• 16

• 20

12

If the cerebellum is seen in a BPD measurement, the plane is ________ in the posterior portion of the image.

• too lateral

• correct

• too high

• too low

too low

The most common and routine measurements to assess the fetal growth and well-being are:

• HL, FL, HC, and AC

• FL, HC, AC, and OD

• BPD, HC, AC, and FL

• BPD, AC, HC, and MFP

BPD, HC, AC, and FL

Select a fetal characteristic that is not a late gestational individuation.

• elongated fetus

• dolichocephaly

• thin fetus

• bradycardia

bradycardia

What structures are seen in an accurate BPD measurement?

• complete oval calvarium, sphenoid, and petrous bones

• thalamus, cavum magnum

• complete oval calvarium with the cerebellum demonstrated

• orbital, base X, occipital

complete oval calvarium, sphenoid, and petrous bones

To estimate an accurate fetal age, the BPD measurement should be obtained before:

• 29 weeks

• 31 weeks

• 33 weeks

• 35 weeks

33 weeks

An HC measurement should be obtained:

• using the inner edge of the calvarium at the level of the BPD

• using the outer edge of the calvarium at the level of the BPD

• using the outer edge of the calvarium at the level of the cerebellum

• at the level of the occipital circumference

using the outer edge of the calvarium at the level of the BPD

Select the correct CI formula:

• (D1 + D2) x 1.57

• BPD/FOD x 100

• 89%/OD x (D1-D2)

• FOD/BPD x 100

BPD/FOD x 100

Platycephaly is:

• premature closure of the cranial sutures

• flattening of the forehead, causing skull widening

• a type of coneheadedness

• shortening of the vertical dimension of the skull

shortening of the vertical dimension of the skull

The most exact of the orbit measurements is the:

• BOD

• OOD

• IOD

• IGE

BOD

All of the following are fetal long bones except:

• tibia

• humerus

• metacarpal

• ulna

metacarpal

Fetal weight by US is frequently requested to rule out all except:

• macrosomia

• BPP

• IUGR

• possible low birth weight

BPP

If the umbilical/ portal junction is not visualized while attempting an AC measurement, use the level of the fetal:

• stomach

• kidneys

• adrenals

• cord insertion

stomach

Preferred technique for measuring the fetal abdomen and head circumference is:

• manual tracing

• ellipse

• inner skin line

• two-point

ellipse

Two purposes for second and third trimester measurement of a fetus are estimating ______ ____ and determining the size and development.

fetal age

Differences in fetal growth parameters can be caused by maternal __________, ___________, and genetics.

smoking; altitude

Normally, conception takes place about ___ weeks after the LMP.

2

Molding and normal morphologic variations of the fetal head have a great effect on the accuracy of the _____ measurement in assessing age.

BPD

Exclude the _____ _______ of the scalp when measuring from the leading edge of the parietal bone for a BPD measurement

soft tissue

When taking fetal measurements, always use the transducer and focal range that provide the ____________ resolution.

highest

Macrosomia equates to a fetus over ________g.

4,000

If the fetal head is very low in the pelvis, a(n) _____ transducer may allow accurate BPD measurements.

EV

The head circumference should be measured on the same image used for the _____ measurement.

BPD

The more measurements obtained and averaged during a fetal US, the more ___________ the fetal age estimate.

accurate

MFP (__________ ______ ___________) is the average gestational age determined by four common measurements of the fetus.

multiple fetal parameter

A measurement of the HC using the perimeter tracing method should be made around the ___________ edge of the calvarium.

outer

A fetus with a long and narrow head is called __________________.

dolichocephalic

Cerebellar size is generally unaffected by fetal ________ disturbances and is independent of the shape of the ___________.

growth; cranium

A correct AC measurement demonstrates the __________ vein junction with the _________ vein perpendicular to the ________.

umbilical; portal; spine

A structure within the cranium that maintains a relationship to fetal growth throughout pregnancy is the _______________.

cerebellum

Common fetal body ratios are _____/___; ___/___; and ___/___.

BPD/FL; HC/AC; and AC/FL

The recommended technique to obtaining an accurate AC is to first locate the long axis of the ________ ______.

fetal spine

The outer ______ line must be included in the abdominal circumference so that AC is not underestimated.

skin

The femur measurement can be reliably used after ____ weeks gestation.

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