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Gestational sac endovaginally will appear as echogenic thickening in the fundus at what week
3-4wks
small hypoechoic area appears in the fundus with double decidual sac sign will appear at what week
4wks
What is the echogenic rim that is seen within the choriodecidual tissue
chorionic sac
Endovaginally mean sac diameter will provide an estimate of gestational age at what week
5wks
How much does the sac increase each day in the first 10 wks
1mm
When the gestational sac exceeds 8mm MSD, what can be seen
yolk sa
Small anechoic circular structure within the gestational sac
yolk sac
The yolk sac should measure
<6mm
Gestational sac at 16mm should show what endovaginally
embryo with cardiac activity
Gestational sac will be seen with a BHCG of
500mlU/mL
What is the normal CRL
1-2mm
What is the most accurate sonographic technique for establishing gestational age in the first trimester
CRL
CRL can be taken from which weeks
6-12wks
A CRL of >7mm should show what transabdominally
cardiac activity
How much does the CRL increase each day
.8mm
If embryo is not seen by 7-8wks, what is suggested
demise or anembryonic pregnancy
What week should you begin getting the first heartbeats
5wks
What is the approximate heart rate between the first beat and 9th week
100bpm
What is the formula for embryonic age
LMP days = EHR x .3 + 6 days
What is the mot widely accepted means of measuring the fetal head and estimating fetal age in the 2nd/3rd trimester
BPD
How much does the skull grow each week in the 2nd trimester
3mm
How much does the skull grow each week in the 3rd trimester
1.8mm
What should be measured perpendicular to the fetal skull at the level of the thalamus and septum pellucidum
BPD
What are the landmarks for the BPD measurement
flax, CSP, thalamus, and choroid plexus in the atrium of each lateral ventricle
Brachycephaly
round head
dolichocephaly
elongated head
How should your calipers be placed for a BPD measurement
outer to inner
parietal bones should not exceed
3mm
rhombencephalon should begin to be seen at what week
8wks
Fetal skull compression occurs with
normal vertex position
uterine tumors
intrauterine crowding
What other measurement is taken at the level of the BPD
head circumference
What is the formula for head circumference
HC = 1.62 x (BPD + OFD)
Shows a shorted BPD with an elongated OFD
dolichocephaly
shows an elongated BPD with a shortened OFD
brachycephaly
What determines the normality of the fetal head shape
cephalic index
Formula for cephalic index
CI= BPD/OFD x 100
cephalic index for brachiocephalic babies
>85%
cephalic index for dolichocephaly babies
<75%
Fetal measurement used to determine growth but not age
abdominal circumference
What two veins form a J shape together
LPV and RPV
Measured from the major trochanter to the external condyle
femur length
appear as high amplitude echoes that is separate but adjacent to the femur or tibia
distal femoral and proximal tibial epiphyseal
DFE is identified at
>33wks
PTE is identified at
>35wks
Which bone of the lower leg is larger and medial
tibia
Which arm bone is larger and more medial
ulna
What assesses proportionality of fetal parameters
age range analysis
What is the diameter of the orbits at 12wks
13mm
What is the diamter of the orbits at full term
59mm or greater
Note 
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