Maternal Testing And Screening Flashcards

1
Q

What timeframe is classified as 1st trimester screening? 2

A
  1. 11weeks 3 days
  2. 13 weeks 6 days
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2
Q

When is the 2nd trimester detailed anatomy scan?

A

18-20 weeks

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3
Q

When is dating done?

A

1st trimester

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4
Q

When do we do the growth and fetal wellbeing scans? What are some examples?2

A

As needed
1. Fetal assessment scan (FAS)
2. BPP and biometry and doppler

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5
Q

What are triple screen/ quad screen test?

A

Maternal blood test

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6
Q

What are some additional tests done outside of the 1st and 2nd trimester tests? 6

A
  1. Triple screen/ quad
  2. Non invasive prenatal testing
  3. Chorionic vili sampling
  4. Amniocentesis
  5. Percutaneous umbilical blood sample
  6. Fluorescence in Situ hybridization (FISH)
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7
Q

When is triple screen tests done?

A

16 weeks

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8
Q

What do we assess with triple screen?

A
  1. Maternal serum alpha feta protein
  2. Unconjugated estriol
  3. Beta hCG
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9
Q

What does the triple screen help use detect?

A
  1. Trisomy 21
  2. Trisomy 18
  3. other chromosomal abnormalities
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10
Q

What is the detection rates of triple screen?

A

~70%

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11
Q

Where is MS- AFP produced? 4

A

Mainly in the fetal liver also found in
1. Yolk sac
2. GI tract
3. Kidney
4. Placenta

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12
Q

AFP crosses the fetal placenta into what?

A

Maternal circulation

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13
Q

When does the MS-AFP levels rise?

A

About 14-20 weeks

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14
Q

Why would we have abnormal levels for MS AGP? 3

A
  1. Wrong date
  2. multiples
  3. Fetal abnormality
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15
Q

What is the MS-AFP for athletic women?

A

Increased MS- AFP

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16
Q

What does abruptions cause in terms of MS-AFP?

A

Increase it if enough fetal and maternal blood mix

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17
Q

What is a pro and con for MS-AFP?

A

It is sensitive but not specific

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18
Q

If MS- AFP is decreased it is related to what? 2

A
  1. Trisomy 21
  2. Trisomy 18
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19
Q

If MS-AFP is increased it is related to what? 7

A
  1. Open neural tune defect
  2. Gastroschisis
  3. GI obstruction
  4. Cystic hygrometer
  5. RH sensitivity
  6. Placental abnormality
  7. Fetal death
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20
Q

Beta HCG is produced by what?

A

Trophoblasts which become the placenta

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21
Q

If beta hCG is increased what does it mean? 4

A
  1. Multiples in pregnancy
  2. Molar pregnancy
  3. Wrong dates
  4. Trisomy 21
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22
Q

If beta hCG is low what does it mean?

A

Trisomy 18

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23
Q

What produces unconjugated estriol?

A

Fetal adrenal glands and liver produce and synthesize a hormone that travels to the placenta which deconjugates it to estriol

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24
Q

Fetal malformations disrupts the normal process resulting in what?

A

Unconjugated estriol in the maternal blood

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25
Q

Decreased levels of unconjugated estriol are a marker for what? 2

A

T21 and T18

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26
Q

What do we look for in a quad screen?

A

Triple screen + Hormone Inhibin A

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27
Q

What produces inhibin A?

A

The baby and the placenta

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28
Q

Increased levels of inhibin A suggest what?

A

T21

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29
Q

According to AHS those that have inhibin A, we will find what? 3

A
  1. Neural tube defects 80% of the time
  2. Anencephaly 95% of the time
  3. Down syndromes 81% of the time
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30
Q

What is the 1st trimester screen test?

A

Early risk assessment

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31
Q

What does the 1st trimester screen test combine? 3

A
  1. Nuchal translucency
  2. Blood test
  3. Maternal age
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32
Q

What does the 1st trimester test screen for? 3

A
  1. T13
  2. T18
  3. T21
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33
Q

What is the detection rate for 1st trimester screen?

A

85-90%

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34
Q

What is the false positive rate for T21, in the 1st trimester scan?

A

5%

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35
Q

What is the 1st trimester screen positive screen tests for T21, T18, T13?

A
  1. T21 = 1:300
  2. T18 = 1:1100
  3. T13 = 1:3000
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36
Q

In the 1st trimester, all trisomy’s are associated with what? 3

A
  1. Increased maternal age
  2. Increased fetal NT
  3. Decreased PAPP-A
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37
Q

In the 1st trimester scan, T21 B hCG levels are what?

A

Increased

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38
Q

For Trisomy 18 and 13 in the 1st trimester, Free B-hCG look are what?

A

Decreased

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39
Q

In the 1st trimester, when the presence of a nasal bone is assessed in the NT scan the detection rate is what?

A

Increased to 95%

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40
Q

When would a nasal bone considered hypoplastic or absent?

A

<2.5mm

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41
Q

What does NIPT stand for?

A

Non invasive prenatal testing

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42
Q

When is blood test taken for NIPT?

A

Maternal blood test taken at 10 weeks LMP

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43
Q

What do we test for during NIPT?

A

Testing the cell free DNA (cfDNA) in maternal plasma

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44
Q

How accurate is NIPT?

A

Extreme accurate >99% detection rate
False positive rate <0.1%

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45
Q

What are some maternal factors to consider for NIPT?

A

Increased maternal BMI can result in false negative result

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46
Q

Is NIPT considered a screening?

A

Yes

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47
Q

When is transcervical CVS performed?

A

Between 11- 12.5 weeks

48
Q

How is transcervical CVS done? 2

A
  1. Catheter inserted through cervix to chorion frondosum
  2. With negative pressure from syringe, moving catheter back and forth to capture chorionic villi cells
49
Q

What is a trans abdominal CVS?

A

Needle through abdomen to chorion frondosum

50
Q

When would we perform a trans abdominal CVS?

A

Performed when placenta cannot be accessed by transcervical approach.

51
Q

When can a trans abdominal approach be done?

A

Beyond 12.5 weeks

52
Q

What is the risk for trans abdominal CVS?

A

1/200 risk for spontaneous abortion

53
Q

What is amniocentesis?

A

Amniotic fluid aspirated from the amniotic sac via a needle through the maternal abdomen

54
Q

What are some risks of amniocentesis? 3

A
  1. Bleeding/ infection
  2. PROM/ Preterm labour
  3. Club feet
55
Q

When would club feet be a risk factor for amniocentesis? 2

A
  1. When performed earlier than 16 weeks
  2. 16 weeks is now thought to be the optimum timing
56
Q

What is the risk ratio for amniocentesis?

A

1/200 risk for spontaneous abortion

57
Q

What do we note for amniocentesis? 5

A
  1. Number of fetuses and position
  2. Amniotic fluid volume
  3. Placental location
  4. Gestational age by biometry
  5. Limited anatomical survey -choroids, fetal hart, stomach, bladder, kidney, spine, bones
58
Q

What must we do in terms of amniocentesis for heart rate?

A

Record heart rate with M-mode before and after procedure

59
Q

What do we need to do for guided amniocentesis? 2

A
  1. Observe sterile techniques
  2. Open an amniocentesis tray and add items
60
Q

What is added into amniocentesis tray?

A
  1. Needle = spinal needle - 16, 18, 20 gage
  2. 2 x 10cc syringes
  3. Cleaning solutions will be poured into vails
  4. Transducer supplies
61
Q

What kind of cleaning solutions will be poured into vials for amniocentesis trays? 2

A
  1. Betadine - brown
  2. Alcohol - pink
62
Q

What kind of transducer supplies do we add to the amniocentesis tray? 3

A
  1. BX guide
  2. Probe cover
  3. Sterile gel
63
Q

What is the process for amniocentesis? 3

A
  1. Apply the Bx guide holder to the transducer and apply liberal amounts of gel to the transducer face
  2. Physician will offer the transducer cover to have you “drop” in the transducer
  3. Physician will clean and drape the operative site
64
Q

Can the amniocentesis needle position be distorted?

A

Yes to due to refraction and reverberation artifacts

65
Q

Why would physician scan to locate a pocket of amniotic fluid?

A

It is ideal to have no umbilical cord baby in pocket

66
Q

How much cc’s of amniotic fluid is aspirated into each syringe?

A

10cc

67
Q

Once the physician has the appropriate amount of fluids they will empty the contents how? Typically not how? Sometimes we do what? What must be on each vial?

A
  1. Into two vials
  2. Typically not on the sterile tray
  3. Sometimes we will assist by holding vials or they empty post procedure
  4. Patient identification information must be vials
68
Q

What must we always do with the patient vials?

A

Confirm the patients ID on the vials with the patient or physician

69
Q

What are the different types of amniocentesis? 4

A
  1. Cytogenetic amniocentesis
  2. O.D.D (Optical density determination)
  3. L/S amniocentesis
  4. Therapeutic
70
Q

What is the most common reason to perform an amnio?

A

Cytogenetic amniocentesis to look for chromosomes

71
Q

What is the reason to do O.D.D scans?

A

Rh sensitized fetuses

72
Q

What is L/S amniocentesis?

A

Fetal lung maturity

73
Q

Why would we do therapeutic amniocentesis?

A

For polyhydraminos

74
Q

Amniotic fluid contains what kind of skin cells?

A

Fetal skin cells

75
Q

The amniotic fluid is prepared how for analysis?

A

Cultured for analysis

76
Q

What does cytogenetic amniocentesis do?

A

Fetal DNA is analyzed and biochemistry (AFP) tested

77
Q

When can cytogenetic amniocentesis be performed?

A

Anytime after 11 weeks

78
Q

Abnormalities detected at 18-20 week detailed scan will often require what?

A

Amniocentesis for chromosome analysis

79
Q

Anomalies detected at any time will be offered what?

A

An amnio

80
Q

When is cytogenetic amniocentesis routinely done?

A

16 weeks

81
Q

Why would we do cytogenetic amniocentesis? 3

A
  1. Advanced maternal age
  2. Hx of congenital abnormalities in the previous pregnancy
  3. Family Hx in a direct relative to the fetus
82
Q

How do we do Twin amniocentesis? 2

A
  1. First baby: After amniotic fluid aspired from the gestation sac Indigo carmine is injected into this sac
  2. If purple fluid is drawn out of the second baby we have the wrong sac
83
Q

What is O.D.D?

A

Optical density determination

84
Q

What does O.D.D. Measure?

A

Bilirubin levels in RH sensitized pregnancies

85
Q

When is O.D.D. done?

A

Usually late 2nd semester or 3rd trimester

86
Q

What is O.D.D. Sample?

A

Photosensitive sample

87
Q

What is L/S sample stand for?

A

Lecithin/ Sphingomyelin ratio for lung maturity

88
Q

What is Lecithin and sphringomylein?

A

Surfactants

89
Q

What does lecithin and sphingomyelin do?

A

Responsible for the decrease in the surface tension in the alveoli of the lungs

90
Q

What is the percentage of L/S ratio dispersed through the amniotic fluid?

A

Fairly equal in the amniotic fluid up to 33 weeks gestation

91
Q

After the decrease of the surface tension in the alveoli of the lungs, what happens to Lecithin and sphingomyelin? 2

A
  1. Lecithin increases
  2. Sphingomyelin remains constant
92
Q

If the L/S ratio is greater than two, what does this mean?

A

Lungs are considered mature

93
Q

When is L/S ratio performed?

A

In 3rd trimester

94
Q

Why is L/S ratio done?

A

When elective early delivery or repeat C-section is being offered

95
Q

How common is L/S ratio?

A

Rarely performed now

96
Q

What can therapeutic amniocentesis be done for? 3

A
  1. Polyhydraminos
  2. Twin to twin transfusion
  3. Hydrops
97
Q

When would we do therapeutic amniocentesis? 3

A
  1. Mother is not able to tolerate pressure
  2. Enlarged uterus presses on abdominal contents
  3. Can cause SOB
98
Q

When do we do Therapeutic amniocentesis?

A

As needed because fluid will reaccumulate within days

99
Q

In terms of CVS vs amniocentesis, which obtains more DNA?

A

CVS

100
Q

In terms of CVS vs amniocentesis, which one gets faster results?

A

Amniocentesis

101
Q

What does PUBS stand for?

A

Percutaneous umbilical blood sampling

102
Q

What is PUBS also know as?

A

Cordocentesis

103
Q

How is PUBS performed?

A

Ultrasound guided needle into the umbilical cord ~1cm from insertion into placenta

104
Q

What do we sample with PUBS?

A

Umbilical vein rather than artery

105
Q

What is done prior to PUBS? 5

A

Pre-scan
1. FHR
2. Fetal position
3. AFI
4. Placental location
5. Placental cord insertion

106
Q

How much blood is taken during PUBS during 2nd trimester?

A

Up to 4mls

107
Q

How much blood is taken during PUBS during 3rd trimester

A

Up to 6ml of blood

108
Q

What do we need to check 10 min post PUBS procedure?

A

Bleeding

109
Q

What do we check 60 min post PUBS procedure?

A

FHR

110
Q

What are some indications for PUBS testing? 6

A
  1. Fetal anemia in RH sensitization
  2. Fetal Blood transfusion
  3. Chromosomal analysis within 72 hours
  4. Fetal blood gas sampling in IUGR
  5. Fetal infection
  6. Treat fetal arrhythmias w/ medications
111
Q

What are some risks of PUBS? 5

A
  1. Bleeding from puncture site s
  2. Infection
  3. Cord hematoma
  4. Rupture of membrane s
  5. Fetal loss (1%-5%)
112
Q

What does FISH stand for?

A

Fluorescence in Situ hybridization

113
Q

What does FISH look for?

A

How many copes are present for specific chromosome like 13, 18, 21, X and Y

114
Q

What is a advantage of FISH?

A

It does not require all the steps needed as in cytogenetic karyotyping

115
Q

What is a disadvantage of FISH?

A

No information on the structure of the chromosome

116
Q

What is FISH performed on? 3

A

Fetal blood, amniotic fluid and/ or CVS

117
Q

How fast do we get the results of FISH?

A

Very fast within 3-4 days