Prenatal Flashcards

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1
Q

% major Fetal abns related to Chr abnormalities

A

20-25%

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2
Q

% improvement the detection rate of Chr abns using aCGH over largo typing

A

4-6%

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3
Q

Study comparing 5 array platforms

A

Huang and Crolla. 2010. Comp 5 array platforms and software- 12 samples- all needed comparable Dan concn. and DR=93-100%

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4
Q

Key aim with use of aCGH in prenatal setting

A

Need balance of optimal resolution and coverage. Targeted/low res array will miss abns and higher density will increase cnvous

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5
Q

Advantage of using aCGH in prenatal so

A

No culture req- increase tat, decrease cultural artefact, better DR, pick up cryptics

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6
Q

Disadvantage of prenatal aCGH

A

Poor quality and quantity of dna , miss balanced rea, miss lower level mosaic, triploidy missed,still need culture for f/u fish, cnvous->anxiety, counselling issues ass with cnvous and inc penetrance

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7
Q

How many extra cyto cryptic abnormalities are seen on aCGH

A

1-3% in some studies

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8
Q

What are prenatal aCGH best practice guidelines

A

None specifically, guidelines based on results of EACh study

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9
Q

Hillman et al 2011 reviewed outcomes of pCNV in prenatal setting- what are they?

A

12% cnv seen in all foetuses (3.6% were pathogenic), 11.2% cnv seen in abscan referrals (5.2% pathogenic)

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10
Q

When should a deletion of an autosomal recessive condition be reported

A

Only if carrier freq is high. Consider late onset with clinical utility

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11
Q

Definition of screening

A

Process to ID apparently healthy people at an increased risk of a condition. Can then be offered further tests or treatment to decrease risk and/or complications

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12
Q

3 considerations of effective screening

A

High DR, low FPR, low FNR

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13
Q

By 2010 all nhs trusts were expected to provide what DR and FPR for aneuploidy screen

A

> 90% dr and

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14
Q

What is the FASP

A

Fetal anomaly screening prog.overseen by uknsc.

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15
Q

Risk of trisomy 21 at 49 years

A

1:85

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16
Q

Risk if T21 at 30

A

1:940

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17
Q

Risk if T21 at 20

A

1:1450

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18
Q

Risk if T21 at 35

A

1:350

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19
Q

What was the DR for a 5% FPR when using maternal age only

A

DR 30%

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20
Q

What is the current DS screening uptake (according to RAPID)

A

66%

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21
Q

What is national target for timescale of offering one for high risk screen patients

A

97% in 3 days

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22
Q

what is MoM

A

Multiple of mean

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23
Q

How is MoM calculated

A

Concentration of marker for a patient divided by concentration of that marker in general popn

24
Q

What is measured in triple test

A

Afp, beta hcg and uE3

25
Q

Dr for 5% FPR for triple test

A

77%

26
Q

What markers are measured in quad test

A

UE3, beta hcg, inhibinA and afp

27
Q

Quad test dr for 5% FPR

A

81%

28
Q

What is measured in combined test

A

NT, Papp-a and beta hcg

29
Q

What is dr for 5% FPR for combined test

A

87%

30
Q

What is integrated test

A

Trimester 1: nt, Papp-a and beta hcg. Trimester 2: afp ue3 and inhibin a

31
Q

What is dr for 5% FPR for integrated test

A

96%

32
Q

Why isn’t integrated test recommended

A

25% do not attend second appt

33
Q

Factors affecting serum levels

A

Weight less in heavier women, Afro caribeans increased compared with Caucasian, Ivf pregnancies, smokers have lower Pappa hcg and higher inhibin-a, increased levels in twins

34
Q

Future if prenatal trisomy screening

A

Nipt, proteomics using mat serum

35
Q

Describe the marker AFP

A

Produced by yolk sac and liver, concn increases with gestation, increased in NTD and decreased inT21.

36
Q

What marker results will be seen in T21 pregnancy

A

Decreased AFP, ue3 and increased Papp-a, beta hcg and inhibin a

37
Q

What is papp-a marker

A

Pregnanc associated plasma protein a. Origin is placental synctiotrophoblast, increased in T21, pre eclampsia iugr, increase with gestation

38
Q

What is ue3

A

Unconjugated estriol. Only produced in dig amounts by placenta. Increase concn with gestation. Decreased in T21

39
Q

What is inhibin-a

A

Produced by placenta, decrease with gestation to 17wk then increase. Increased in T21

40
Q

What is beta hcg

A

Peptide hormone, made by embryo soon after conception then by synctiotrophoblast. Concn decrease with gestation, screen sensitivity maintained in 2nd trimester. Increased in T21

41
Q

Why do the 10-14 week first trimester scan

A

Dating, measure NT, check placenta location number of babies

42
Q

Nt will detect what % T21

A

75-85%

43
Q

% Chr abn pregnancies with NT under 3.5mm

A

0.2%

44
Q

DS with no nasal bone

A

Absent nasal bone detect60-70% DS

45
Q

% Chr abnormal fetus that have holoprosencephaly

A

30%

46
Q

What is associated with holoprosencephaly on scan

A

T13, T18 and 7q36 deln

47
Q

Abscan in T21

A

Nuchal oedema, heart, duodenal atresia, but only 75% t21 have major anomalies on uss

48
Q

Abscan for T13

A

Holoprosencephaly, iugr, heart, renal,echo genie large kidney, eximohals post axial polydactyly

49
Q

Abscan for triploidy

A

Diandry: molar prey rare +20 weeks, digyny: thin placenta, severe iugr, vebtriculomegaly, syndactyly

50
Q

Abscan t18

A

Strawberry head, cpc, absent corpus collosum, cleft, iugr, overlap fingers , exomohalos diaphragmatic hernia

51
Q

Abscan turners

A

Cystic hygroma, oedema, horseshoe kidney, pleural effusion ascites heart

52
Q

Abscan PK

A

Diaphragmatic hernia , shirt limb, abn hands and feet

53
Q

Abscan Roberts syndrome

A

Severe limb shortening (upper) oligodactyly thumb aplasia cystic kidney

54
Q

Abscan mosaic T2

A

Absent gall bladder talipes renal cyst omphalocele

55
Q

% woman who screen as high risk

A

3%