Lecture 4B - 1st Trimester (Late)

Question 1

In the first trimester late scan, what additional patient history question do you ask (in addition to questions asked to at dating scan)

Answer 1

previous pregnancies with chromosomal abnormality

Question 2

what fetal anatomy features can you visualize by 11-14 week (late 1st trimester scan) (4)

Answer 2

skull
nasal bone
jaw angle
chin/chest separation

Question 3

what late 1st trimester measure correlates to GA?

Answer 3

biparietal diameter (BPD)

Question 4

how would you measure BPD

Answer 4

outer to inner

Question 5

what is the hindbrain called and what does it look like

Answer 5

rhombencephalon - posterior anechoic structure

Question 6

what are the main measurements in 1st trimester late

Answer 6

biparietal diameter
nuchal translucency
femur length

Question 7

when is nuchal translucency assessed?

Answer 7

assessed between 11 w - 13w 6 days (14 weeks too late)

Question 8

nuchal translucency measurements are valid ONLY IF ……

Answer 8

CRL is between 45-84 mm

Question 9

NT should measure

Answer 9

<3 mm

Question 10

what is a pitfall to measuring NT?

Answer 10

potential to include amnion, should show as separate

Question 11

how do you measure NT? (landmarks and actual measurement location)

Answer 11

perfectly midline with nasal bone, head and chest in image

INNER TO INNER at widest

Question 12

what should NOT be in NT image

Answer 12

no zygomatic bone, no eye, no flex/extension of neck

Question 13

what does increased NT indicate

Answer 13

indicates increased risk for chromosomal abnormalities (trisomy 13,18,21)

Question 14

NT measurement increases with (2)

Answer 14

GA and maternal age

Question 15

what does maternal serum screening measure? (2)

Answer 15

b-hCG and PAPP-A

Question 16

what serum markers may indicate trisomy 21

Answer 16

increase b-hCG

decrease PAPP-A

Question 17

what may nuchal edema be?

Answer 17

cystic hygromas +/- generalized gychops