Module 18 : Nuchal Lucency Flashcards
1
Q
what is the incidence of chromosomal abnormalities increased with with NL
A
- size of NL rather than appearance
2
Q
what is the window of opportunity to do a NL
A
- 11weeks - 13 6 days
- 45mm - 84mm
3
Q
why do we have to start to NL at 11 weeks
A
- in a fetus with chromosomal abnormality the nuchal fluid begins to increase at 11 weeks
4
Q
what other abnormalities can we see at the NL scan
A
- acrania
+ skull ossified around 11 weeks - ompalocele
+ normal up until 11 weeks
5
Q
why end at 13 w 6 d
A
- in a fetus with a CA the nuchal fluid decreases after 14 weeks
6
Q
how accurate is the nuchal scan what makes it more accurate
A
- very accurate
- with first trimester blood work is even more accurate
7
Q
what can a this nuchal be indicative of
A
- chromosomal defect
- cardiovascular defect
- pulmonary defect
- skeletal dyplasia
- congenital infectious
- hematologic disorders
- metabolic disorders
8
Q
protocol for measuring CRL
A
- measure with spine anterior or posterior
- midline sag plane
- do not use coronal plane
- fetus in neutral plane `
9
Q
what are the 5 criteria for NL
A
- magnification
- positon
- amnion
- measurement area
- caliber placement
10
Q
magnification
A
- only fetal head and thorax on image
- about only 3-4 cm of depth
11
Q
position
A
- true sagittal on fetus \+ nasal bone an nuchal together - fetus in neutral position \+ hyperextension can create a 0.6mm increase \+ flexion can create a 0.4mm decrease \+ head turned increase NL as well
12
Q
amnion
A
- fetus should be lifted off the amnion
13
Q
measurement area
A
- measure widest portion the NT
- anywhere from the occiput to the thorax
14
Q
calliper placement
A
- on to on
- only cross calipers
- cross hairs line up with top and bottom of membrane
15
Q
what factors are part of the risk assessment
A
- maternal age
- CRL
- NT
- blood analysis
- fetal heart rate
