Second and Third Trimester- Basic Scan Flashcards
1
Q
The second trimester is what weeks?
A
13-27 (3-6 months)
2
Q
Between what weeks can performing an ultrasound allow you to image all organs and predict due date?
A
16-26 weeks GA
3
Q
The spine can be identified sonographically by which week?
A
16-18 weeks
4
Q
The spine is completely ossified by?
A
Week 18
5
Q
The 3 ossification centers can be seen by?
A
16 wks GA
6
Q
What are the 3 ossification centers?
A
2 posterior (laminae) and 1 and anterior (centrum)
7
Q
The 3 ossification centers are best seen in which plane?
A
Transverse
8
Q
The central portion of the spine appears how sonographically?
A
hypoechoic
9
Q
The lumbosacral spine is not completely ossified until?
A
> 18 wks GA
10
Q
Where can the lateral ventricles be seen?
A
on either side of the midline falx
11
Q
The midline falx is also called?
A
interhemispheric fissure
12
Q
The lateral ventricles should not exceed?
A
10 mm
13
Q
How do you measure the lateral ventricles?
A
inner to inner through the atrium
14
Q
True or False: Both the normal anterior and posterior horns of the lateral ventricles are seen sonographically
A
False; only posterior horns
15
Q
Where is hydrocephalus first seen?
A
lateral ventricles (dilated lateral ventricles or ventriculomegaly)
16
Q
Where is the choroid plexus located?
A
in the lateral ventricles
17
Q
How does the choroid plexus appear sonographically?
A
echogenic
18
Q
What is the function of the choroid plexus?
A
produce CSF
19
Q
By when is the brain anatomy visualized?
A
12-14 wks GA
20
Q
Where can the thalami be visualized?
A
on either side of the midline
21
Q
What serves as the landmark for the BPD and HC?
A
thalami, CSP, midline falx
22
Q
What is the thin echogenic line seen between the thalami?
A
third ventricle
23
Q
Where can the cisterna magna be visualized?
A
in the posterior fossa posterior to cerebellum
24
Q
The cisterna magna should never exceed?
A
10 mm
25
Where is the cerebellum located?
in the posterior fossa
26
How does the cerebellum appear sonographically?
two hypoechoic lobes with an echogenic vermis seen between
27
An absent vermis can cause?
splaying of cerebellum
28
What is the cavum septum pellucidum (CSP)?
slit like space that is midline separating the anterior horns of lateral ventricles
29
How does the CSP appear sonographically?
anechoic rectangle in anterior part of the head
30
Circulation of CSF
1. CSF produced by choroid plexus
2. Flows through Foramen of Monro to 3rd ventricle (between thalamus)
3. Aqueduct of Sylvius connects 3rd and 4th ventricle
4. CSF flows through subarachnoid space through the Foramen of Luschka and Foramen of Magendie
5. CSF is absorbed into dural venous sinuses via arachnoid villi
31
The nuchal thickness (nuchal fold) should not exceed?
< 5-6 mm
32
How does CSF appear sonographically?
anechoic
33
By when is the 4 chamber heart identified sonographically?
16-18 wks
34
The apex of the heart should point where?
left side of fetus
35
Which portion of the heart is closest to the chest wall?
right ventricle
36
Which portion of the heart is closest to the spine?
Left atrium
37
The fetal heart should occupy ______ of the chest.
1/3
38
Where is the tricuspid valve located?
between the right atrium and right ventricle
39
Where is the mitral/bicuspid valve located?
between left atrium and left ventricle
40
The foramen ovale shunts blood from?
the right atrium to the left atrium
41
The foramen ovale turns into what when it closes?
fossa ovalis
42
Which portion contains more oxygenated blood?
left atrium
43
What is the normal fetal heart rate?
120-160 bpm
44
A fetal heart rate of < 100 bpm indicates?
bradycardia
45
A fetal heart rate of >180 bpm indicates?
tachycardia
46
Which ventricle has thicker walls? why?
left; higher forces needed to pump blood through body
47
The fetal stomach is identified sonographically by?
Wk 10; better seen by wk 14 due to improvement of fetal swallowing
48
How does the stomach appear sonographically?
round, fluid filled structure on **left** side of fetal abdomen
49
What are the landmarks for AC?
stomach, portal vein, spine
50
The gallbladder is identified sonographically at?
20 wks GA
51
Where is the gallbladder located?
right of midline
52
The fetal adrenal glands have a _______ adrenal cortex and a ______ medulla.
hypoechoic; echogenic
53
The fetal kidneys start producing urine when?
13-15 wks
54
what structure in the heart can be confused for a fetal anomaly?
chordae tendineae
55
What is a major component of amniotic fluid?
fetal urine (16-18 wks GA)
56
By when are the kidneys more visible?
3rd trimester
57
How do the renal pelves appear sonographically?
anechoic slit within central kidney
58
How do the renal pelves appear sonographically?
anechoic slit within central kidney
59
The renal pelves should not exceed?
6 mm
60
What vessels does the umbilical cord consist of?
2 umbilical arteries and 1 umbilical vein (3 vessel cord)
61
The 3 vessels of the umbilical cord creates what sonographically?
mickey mouse sign
62
True or false: Some umbilical cords can have 1 umbilical artery and 1 umbilical vein
True (2 vessel cord); normal varient
63
What kind of blood do the umbilical arteries carry?
deoxygenated
64
The umbilical arteries arise from which vessels?
hypogastric arteries
65
The umbilical vein carries what kind of blood?
oxygenated
66
The umbilical vessels are encased by?
wharton’s jelly
67
True or False: you should image the umbilical cord with color doppler
False; can cover defects
68
What is a nuchal cord?
umbilical cord encircles fetal neck
69
By when is the bladder identified sonographically?
10 wks
70
The fetal bladder fills every ______.
30 minutes
71
What can be indicated by a failure to image the bladder?
UTI
72
True or False: A UTI can be life threatening to a fetus
true
73
What is the measurement for GA in the third trimester?
Femur length
74
How do you measure the femur length?
measure the diaphysis
75
What is the lateral bone of the lower arm? Medial bone?
radius; ulna
76
What is the lateral bone of the lower leg? Medial bone?
fibula; tibia
77
True or False: Hands and feet are required for basic guidelines
False; not required
78
True or False: BPD and HC are measured on the same plane
True
79
Where should the fetal head measurements be taken?
at the level of the thalamus and CSP in the axial plane
80
What are the most accurate measurements of the second trimester?
**BPD** and HC
81
How is the BPD measured?
from outer edge of partietal bone to inner edge of parietal bone (leading edge to leading edge)
82
How is the HC measured?
outer to outer
83
What is OFD?
Occipito-frontal diameter
84
When do you use OFD?
when head shape is questionable (not oval)
85
Mesocephalic
normal shape (70-86% CI)
86
Dolicocephalic
long and narrow (<70% CI)
87
Brachycephalic
broad and round (>86% CI)
88
Brachycephalic
broad and round (>86% CI)
89
Which head shape is associated with Down Syndrome?
Brachycephalic
90
What is the CI?
cephalic index
91
The AC is measured at what level?
level of stomach and junction of umbilical vein and left branch of portal vein
92
True or False: The AC measurement includes fetal skin
True
93
True or False: the kidneys and adrenal glands are not included in AC
true
94
In the second trimester, what can signify the gender is a boy?
turtle sign
95
In the second trimester, what can signify the gender is a girl?
hamburger sign
96
Amniotic fluid is 98% ______
water
97
What is the function of amniotic fluid?
protects fetus, regulates body temperature, allows for movement, aids in development of muscles and skeletal structures
98
What is amniotic fluid critical for?
fetal lung development
99
What is the AFI
amniotic fluid index
100
How do you measure AFI?
divide the uterine cavity into 4 quadrants and measure the deepest pocket of each quadrant then add all 4 measurements
101
What is the normal range of the AFI measurement?
> 8 and <24 cm
102
What is SDP?
single deepest pocket
103
How do you measure SDP?
find the deepest pocket of fluid
104
What is the normal range for the SDP?
> 2 and < 8 cm
105
Define polyhydramnios and it’s measurements for AFI and SDP
too much amniotic fluid; AFI: > 24 cm; SDP: > 8 cm
106
True or false: polyhydramnios provides good resolution
True
107
Define oligohydramnios and it’s measurements for AFI and SDP
not enough amniotic fluid; AFI: < 8cm; SDP: < 2 cm
108
True or false: oligohydramnios provides good resolution
false; poor resolution
109
SDP is also called?
MVP (maximal vertical pocket)
110
What is vernix and how does it appear sonographically
normal desquamated skin cells, she’d hair, and sebum; echogenic particles in amniotic fluid
111
What is meconium and how does it appear sonographically?
menacing sign of bowel contents in amniotic fluid; grey and hazy
112
What is the formula for CI?
BPD/OFD x100
