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DMST 315 OBGYN 3 > Module 15: Nuchal Transluency > Flashcards

Module 15: Nuchal Transluency Flashcards

1
Q

What is nuchal translucency?

A

The sonographic appearance of subcutaneous accumulation of fluid behind the fetal neck in the first trimester of pregnancy

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2
Q

In terms of Nuchal translucency, The term translucency is used irrespective of what?

A

Whether it is septated or not and whether it is confirmed to the neck or envelopes the whole fetus

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3
Q

The incidence of chromosomal and other abnormalities is related to NT how?

A

Size rather then to NT

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4
Q

In terms of NT, during the second trimester, the translucency usually does what? In a few cases what happens?

A

Resolves and in a few cases it evolves into either nuchal edema orcystic hygromas with or without generalized hydrops

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5
Q

In a fetus with a chromosomal abnormality the nuchal fluid begins to increase at what weeks?

A

11 weeks

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6
Q

What other abnormalities can we sonographically appreciate at 11 weeks? 2

A
  1. Acriana
  2. Omphalocele
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7
Q

When does a skull finish ossifying?

A

Skull ossified around 11 weeks

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8
Q

Omphalocele is normal to have midgut hernia from what weeks? But not after what weeks?

A
  1. 8-10 weeks
  2. 11-12 weeks
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9
Q

In a fetus with a chromosomal abnormalities, the nuchal fluid can decrease after how many weeks?

A

14 weeks

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10
Q

Patients can have 1st trimester termination if what is found?

A

An abnormality

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11
Q

It is more difficult to obtain NT after how many weeks? Why?

A
  1. 14 weeks
  2. More vertical fetal position
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12
Q

Do not proceed to perform a NT when what happens? Why?

A
  1. If the CRL is over 84mm
  2. The Test is not valid on a fetus that is over 13w6d
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13
Q

NT on its own is how accurate?

A

80%

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14
Q

Nuchal translucency with 1st trimester blood work is how accurate?

A

90%

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15
Q

What are some 1st trimester blood work tests? 3

A
  1. bHCG
  2. PAPPA
  3. OSCAR
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16
Q

What is OSCAR?

A

One stop clinics for early assessment of fetal risk - which have 30 minute lab processing time

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17
Q

Nasal bone is not visible in 60-70% of fetus with what?

A

T21

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18
Q

What disorders are associated with increased nuchal translucency? 7

A
  1. Chromosomal defects
  2. Cardiovascular defect
  3. Pulmonary defect
  4. Skeletal dysplasia
  5. Congenital infections
  6. Haematological disorders (anemia)
  7. Metabolic disorders (hypoproteinemia)
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19
Q

What position should the baby be when we measure CRL? 4

A
  1. Spine anterior or posterior
  2. Midline sagittal plane
  3. Do not use coronal plane
  4. Fetus should be in a neutral position
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20
Q

What is the Minimum CRL?

A

45mm (11w)

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21
Q

What is the maximum CRL?

A

84mm (13w6d)

22
Q

What is the criteria for CRL? 5

A
  1. Magnification
  2. Position
  3. Amnion
  4. Measurement area
  5. Calliper placement
23
Q

What is the protocol for NT? 5

A
  1. Magnify/zoom only chest and head on image
  2. Perfect midline sagittal plane
  3. Neutral flexion of the spine
  4. Technical settings - decrease compression
  5. Measure on to on
24
Q

When we are going through the NT protocol, and look at neutral flexion of the of the spine, what do we need to see? 2

A
  1. Chin not on chest
  2. Chin not high off chest
25
Q

When we are doing a magnification of NT what must we see? What should the depth of the screen?

A
  1. Only fetal head and thorax on image
  2. About 3-4 cm depth on screen
26
Q

What is the position the baby should be when we are doing NT? What do we need to see? 3

A
  1. True sagittal on fetus
  2. Fetus in neutral position
  3. Nasal bone an nuchal together
27
Q

Why do we need to see the fetus on neutral position during NT scans? 3

A
  1. Hyperextension can create a 0.6mm increase in NT
  2. Flexion can create a 0.4 decrease in NT
  3. Head turned can increase NT as well
28
Q

What should the fetus position and the amnion look like?

A

The fetus should be lifted off the amnion

29
Q

What is the measurement area for NT? 2

A
  1. Widest position of the NT
  2. Anywhere from the occipital to the thorax
30
Q

What affects the risk assessment of NT? 5

A
  1. Maternal age
  2. CRL
  3. Nuchal translucency
  4. Blood analysis
  5. Fetal heart rate (<170 beats/min)
    Computer program also gives a risk assessment
31
Q

What ratio is considered a positive risk?

A

1/300 or less

32
Q

Just being how old will give you a positive risk no matter the NT?

A

40 years

33
Q

What can assist in making your results for abnormalities negative?

A

Blood work

34
Q

What is offered if there is a risk in pregnancy?

A

Amniocentesis

35
Q

Amniocentesis has a pregnancy loss rate of what?

A

About 1/200

36
Q

The NT normally increase with gestational age up to what time?

A

14 weeks

37
Q

During scans what should we image? 6

A
  1. Heart rate
  2. Cranium
  3. Abdominal wall
  4. Bladder
  5. Stomach
  6. Limbs
38
Q

If we suspect a nuchal umbilical cord, the nuchal measurement is then taken where? What else must we do? 3

A
  1. Above and below the nuchal cord
  2. The measurement is then averaged
  3. Use colour doppler to confirm location of the cord
39
Q

If suspect multiple gestations what must we do? Why?

A
  1. Assess chorioncity and amnionicity
  2. This is the best time to see the membranes, later on this may be very difficult to assses
40
Q

Label

A
41
Q

Label

A
42
Q

What does these images represent?

A

Nasal vs. Absent

43
Q

What does this image represent?

A

CRL

44
Q

What does this image represent?

A

Proper placement of callipers for NT

45
Q

What s this an image of?

A

Proper NT measurements

46
Q

What does this image represent?

A

Proper magnification for NT

47
Q

What is the image pointed to?

A

Amnion

48
Q

Fill in the chart.
99% for both measurements are what?

A

3.5mm

49
Q

Fill in the chart

A
50
Q

What does this image represent?

A

Suspect a nuchal umbilical cord

DMST 315 OBGYN 3 (21 decks)

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