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Year 2 Medicine > Prenatal Screening > Flashcards

Prenatal Screening Flashcards

1
Q

What is screening?

A

Screening identifies apparently healthy people who may be at increased risk of a disease or condition, enabling earlier treatment or informed decisions.

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2
Q

Fetal anomaly screening programme

A
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3
Q

Fetal Anomoly Screening Programme

  • … pregnancy scan
  • Screening for …’s …’s …’s syndromes
    • First trimester … test
    • Second trimester … test
  • ..+.. – ..+.. weeks fetal anomaly scan
A
  • Early pregnancy scan
  • Screening for Down’s Edward’s Patau’s syndromes
    • First trimester combined test
    • Second trimester quad test
  • 18+0 – 20+6 weeks fetal anomaly scan
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4
Q

The early pregnancy scan:
Why scan at 10-14 weeks ?

  • V…
    • …-… % of women attending for scan will have miscarried
  • Accurate …
    • NICE guidance: advise use scan of … in lieu of LMP dates
        • crucial for screening tests for …
      • reduces need for post dates … of labour
  • Detect … pregnancy
    • determine c…
  • Diagnosis of major … anomalies
    • s.. b…
    • an…
    • ex… & gastro…
    • … outflow obstruction
  • Screening for chromosomal conditions:
    • Down’s syndrome -Trisomy …
    • Edward’s syndrome- Trisomy …
    • Patau’s syndrome –Trisomy …
A
  • Viability
    • 2 - 3 % of women attending for scan will have miscarried
  • Accurate dating
    • NICE guidance: advise use scan of dates in lieu of LMP dates
        • crucial for screening tests for trisomies
      • reduces need for post dates induction of labour
  • Detect multiple pregnancy
    • determine chorionicity
  • Diagnosis of major structural anomalies
    • spina bifida
    • anencephaly
    • exomphalos & gastroschisis
    • bladder outflow obstruction
  • Screening for chromosomal conditions:
    • Down’s syndrome -Trisomy 21
    • Edward’s syndrome- Trisomy 18
    • Patau’s syndrome –Trisomy 13
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5
Q

Screening for chromosomal conditions:

  • What 3 ? What Trisomy?
A
  • Down’s syndrome -Trisomy 21
  • Edward’s syndrome- Trisomy 18
  • Patau’s syndrome –Trisomy 13
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6
Q

Screening for Down’s Edward’s Patau’s syndromes

  • First trimester … test
  • Second trimester … test
A
  • First trimester combined test
  • Second trimester quad test
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7
Q

Down’s syndrome - Trisomy …

  • Schematic view of full ….
  • Usually we have … pairs of autosomes and two sex chromosomes making a total of … chromosomes.
  • People with Downs syndrome have an extra copy of chromosome …
  • People with Edwards syndrome have an extra copy of chromosome …
  • People with Pataus syndrome have an extra copy of chromosome …
A

Down’s syndrome - Trisomy 21

  • Schematic view of full karyotype.
  • Usually we have 22 pairs of autosomes and two sex chromosomes making a total of 46 chromosomes.
  • People with Downs syndrome have an extra copy of chromosome 21.
  • People with Edwards syndrome have an extra copy of chromosome 18
  • People with Pataus syndrome have an extra copy of chromosome 13
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8
Q

People with Pataus syndrome have an extra copy of chromosome …

A

People with Pataus syndrome have an extra copy of chromosome 13

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9
Q

People with Edwards syndrome have an extra copy of chromosome …

A

People with Edwards syndrome have an extra copy of chromosome 18

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10
Q

People with Downs syndrome have an extra copy of chromosome …

A

People with Downs syndrome have an extra copy of chromosome 21.

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11
Q

Screening Tests vs Diagnostic Tests

  • Screening Tests
    • identify individuals at ‘high’ or ‘low’ chance of having a baby with the condition screened for
    • A low chance result does … trisomy in the baby.
    • A high chance result does not indicate that the baby is
  • …
    • Risk of miscarriage?
    • Diagnostic Tests
      • give … information on the fetal chromosomes by confirming the presence of an extra chromosome or absence of a chromosome
      • Risk of miscarriage?
A
  • Screening Tests…
    • …identify individuals at ‘high’ or ‘low’ chance of having a baby with the condition screened for
    • A low chance result does not exclude trisomy in the baby.
    • A high chance result does not indicate that the baby is definitely affected.
    • No risk of miscarriage
  • Diagnostic Tests…
    • …give definitive information on the fetal chromosomes by confirming the presence of an extra chromosome or absence of a chromosome
    • Risk of miscarriage
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12
Q

Pregnancy Screening Timeline

A
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13
Q

First trimester combined screening

  • 3 Modalities:
    • Maternal …
    • Nuchal … Scan
    • Blood Test for markers - P… and B…
A
  • 3 Modalities:
    • Maternal Age
    • Nuchal Translucency Scan
    • Blood Test for markers - PAPPA and BhCG
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14
Q

The chance of having a baby with a trisomy increases with …

A

The chance of having a baby with a trisomy increases with maternal age.

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15
Q

Nuchal Translucency [NT] Scan

  • Can only take measurement when CRL 45- 84mm [equates to 11+2 to 14+1 weeks]
    • CRL = crown rump length
  • NT is increased in over …% of cases of T21.
  • …% of T18
  • …% Turners
A
  • CRL 45- 84mm [equates to 11+2 to 14+1 weeks]
  • CRL = crown rump length
  • NT is increased in over 80% of cases of T21.
  • 75% of T18
  • 87% Turners
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16
Q

What are the two maternal serum biochemical markers in combined screening?

A

free B-hCG and PAPP-A

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17
Q

Combined screening:
Maternal serum biochemical markers

  • free ß-… & P…-A
  • Measure the concentration of the markers in the maternal blood stream. In a pregnancy where the fetus has Downs you tend to see a … levels of … in conjunction with … levels of ….
  • In T13/18 both markers tend to be significantly … than average.
A
  • free ß-hCG PAPP-A
  • Measure the concentration of the markers in the maternal blood stream. In a pregnancy where the fetus has Downs you tend to see a higher levels of … in conjunction with lower levels of ….
  • In T13/18 both markers tend to be significantly lower than average.
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18
Q

Maternal /fetal influencing factors for combined screening

  • … age
  • … age
  • E…
  • S…
  • I…
  • … pregnancy
  • W..
  • D…
  • Past history of … abnormality
  • … sex
  • Analytical …
A
  • Maternal age
  • Gestational age
  • Ethnicity - afro caribbean inc PAPPA by up to 60%
  • Smoking - inc BHG by 20% and reduces PAPPA by up t 15%
  • IVF
  • Multiple pregnancy
  • Weight - 3kg error = 5% error in risk calculation
  • Diabetes
  • Past history of chromosome abnormality
  • Fetal sex
  • Analytical Imprecision
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19
Q

Combined screening result process

  • National cut off for high / low chance = 1 in …
  • Higher chance? Phoned within … working days – offer further tests
  • Lower chance? Letter within … weeks
A
  • National cut off for high / low chance = 1 in 150
  • Higher chance? Phoned within 3 working days – offer further tests
  • Lower chance? Letter within 2 weeks
20
Q

National Standards – Performance thresholds for combined screening

21
Q

Pregnancy Screening

  • We can only offer combined test up to …+… weeks.
  • For women booking late, or found to be over 14+1 weeks on scan we have another option – the … test
A
  • We can only offer combined test up to 14+1 weeks.
  • For women booking late, or found to be over 14+1 weeks on scan we have another option – the quadruple test
22
Q

Combined screening result process

  • High chance result anything from 1 in … to 1 in …
  • Low chance result 1 in … or lower
A
  • High chance result anything from 1 in 2 to 1 in 150
  • Low chance result 1 in 151 or lower
    *
23
Q

Detection rate of combined screening test:

  • T21 - …%
  • T13/18 - …%
A
  • T21 - 85% (Down’s)
  • T13/18 - 80% (Edwards/Patau’s)
24
Q

Second trimester maternal serum screening: quadruple test

  • …+… to …+0 weeks: available to late bookers only
  • Only screens for Trisomy …
  • Blood test only [… cannot be used after …+… weeks]
  • Uses gestational age, maternal age, smoking, weight, ethnicity and …
A
  • 14+2 to 20+0 weeks: available to late bookers only
  • Only screens for Trisomy 21
  • Blood test only [NT cannot be used after 14+2 weeks]
  • Uses gestational age, maternal age, smoking, weight, ethnicity and … maternal serum markers
25
Q
  • NT – nuchal translucency
  • The NT scan is not used after … weeks,
A
  • NT – nuchal translucency
  • The NT scan is not used after 14 weeks,
26
Q

The quad test is a blood test measuring … markers in the blood.

A

The quad test is a blood test measuring 4 markers in the blood.

27
Q

Second trimester maternal serum screening: quadruple test - Markers

  • UE3 unconjugated estriol – … hormone
  • AFP alpha fetoprotein – … from …
  • … A placental hormone
  • … beta human chorionic gonadotrophin- placental hormone
A
  • UE3 unconjugated estriol – placental hormone
  • AFP alpha fetoprotein – protein from fetus
  • Inhibin A placental hormone
  • BHCG beta human chorionic gonadotrophin- placental hormone
28
Q

Quad test : Detection rates

  • DR is similar to singleton pregnancy but the SPR doubles.
  • T 21 - DR is …%, Screen positive rate is …%
A
  • DR is similar to singleton pregnancy but the SPR doubles.
  • T 21 - DR is 80%, Screen positive rate is 2.5-3.5%
29
Q

Quad test : Detection rates : Twins

  • Monochorionic twins:
    • DR …% SPR ..%
  • Dichorionic twins:
    • DR …-…% SPR …%
A
  • Monochorionic twins:
    • DR 80% SPR 3%
  • Dichorionic twins:
    • DR 40-50% SPR 3%
  • The combined test is the preferred screening test for twins.
  • Whilst the DR Monochorionic twins is similar to a singleton pregnancy, it is much lower for Dichorionic twins.
  • Thus overall the quad test is less useful for dichorionic twins
  • Therefore women with twin pregnancies require careful counselling about screening tests
30
Q
  • The … test is the preferred screening test for twins.
  • Whilst the DR Monochorionic twins is similar to a singleton pregnancy, it is much lower for … twins.
  • Thus overall the … test is less useful for dichorionic twins
  • Therefore women with twin pregnancies require … …. about screening tests
A
  • The combined test is the preferred screening test for twins.
  • Whilst the DR Monochorionic twins is similar to a singleton pregnancy, it is much lower for Dichorionic twins.
  • Thus overall the quad test is less useful for dichorionic twins
  • Therefore women with twin pregnancies require careful counselling about screening tests
31
Q

Higher chance of T13/18/21 on combined or quad screening test ? What next?

  • Explain result – … the chance: 1 in 50 = 2%
  • Balanced information about the condition
  • Three main options:
    • 1-Do nothing - … the pregnancy without having further tests​
    • 2-Diagnostic … testing [CVS / Amnio]
    • 3-NIPT – non invasive … testing
      • [Available …, planned implementation on NHS in June 2021]
A
  • Explain result – reframe the chance: 1 in 50 = 2%]
  • Balanced information about the condition
  • Three main options:
    • 1-Do nothing - continue the pregnancy without having further tests​
    • 2-Diagnostic invasive testing [CVS / Amnio]
    • 3-NIPT – non invasive prenatal testing
      • [Available privately, planned implementation on NHS in June 2021]
32
Q

Prenatal diagnosis / Diagnostic invasive test

  • Chorionic Villus Sampling CVS …+ weeks
  • Amniocentesis …+ weeks to term
  • Around …-…% risk of miscarriage
    • [higher in …]
A
  • Chorionic Villus Sampling CVS 11+ weeks
  • Amniocentesis 15+ weeks to term
  • Around 0.5 -1% risk of miscarriage
    • [higher in twins]
33
Q

NIPT: Non-invasive prenatal testing Screening for aneuploidy

  • Cell free fetal DNA [cff DNA] in maternal blood from … weeks
  • Pregnancy specific
  • Test maternal blood from … weeks
  • Aneuploidy: Screening for T… sensitivity and specificity over 99%
  • Marketed as Harmony, SAFE, Panorama, NIFTY test
A
  • Cell free fetal DNA [cff DNA] in maternal blood from 5 weeks
  • Pregnancy specific
  • Test maternal blood from 10 weeks
  • Aneuploidy: Screening for T21 sensitivity and specificity over 99%
  • Marketed as Harmony, SAFE, Panorama, NIFTY test
34
Q

Combined Screen Test / NIPT

A
  • Results either:
  • > 99% chance baby has Downs
  • [should be confirmed by invasive test if considering terminatin]
    • < 1 in 10,000 chance baby has Downs
35
Q

NIPT Advantages

  • … detection rates, … screen positive rates
  • Reduction in invasive diagnostic testing [… effective] hence reduction in … caused by invasive testing [CVS/amniocentesis]
  • A further option for women
A
  • High detection rates, low screen positive rates
  • Reduction in invasive diagnostic testing [cost effective] hence reduction in miscarriage caused by invasive testing [CVS/amniocentesis]
  • A further option for women
36
Q

NIPT Disadvantages

  • Screening test: Not … […]
  • Confirm screen positive results with … test
  • Not suitable for …
  • NHS – planned implementation as a 3 year evaluative roll out commencing June 2021
  • Likely to be offered to anyone with … chance result on first or second trimester screening with … or … pregnancy
A
  • Screening test: Not diagnostic [false positives / false negatives]
  • Confirm screen positive results with invasive test
  • Not suitable for everyone
  • NHS – planned implementation as a 3 year evaluative roll out commencing June 2021
  • Likely to be offered to anyone with high chance result on first or second trimester screening with singleton or twin pregnancy
37
Q

18+0 to 20+6 week fetal anomaly ultrasound scan

  • Specifies screening for … conditions where:
    • the baby may benefit from … before or after birth
    • birth is advisable in an … hospital/ centre and/or to … treatment after the baby is born
    • the baby may … shortly after birth
A
  • Specifies screening for 11 conditions where:
    • the baby may benefit from treatment before or after birth
    • birth is advisable in an appropriate hospital/ centre and/or to optimise treatment after the baby is born
    • the baby may die shortly after birth
38
Q

11conditions screened at mid trimester scan

39
Q

11 conditions screened at mid trimester scan are:

A
  • Anencephaly - DR is 98%
  • Open spina bifida DR is 90%
  • Cleft lip DR is 75%
  • Diaphragmatic hernia DR is 60%
  • Gastroschisis DR is 98%
  • Exomphalos DR is 80%
  • Serious cardiac anomalies includes the following: DR is 50%
    • Transposition of the Great Arteries (TGA)
    • Atrioventricular Septal Defect (AVSD)
    • Tetralogy of Fallot (TOF)
    • Hypoplastic Left Heart Syndrome (HLHS)
  • Bilateral renal agenesis DR is 84%
  • Lethal skeletal dysplasia DR is 60%
  • Edwards’ syndrome (Trisomy 18) DR is 95%**
  • Patau’s syndrome (Trisomy 13) DR is 95%**

**Detections rates will be reviewed once sufficient data is received following implementation of screening as part of the combined screening strategy

40
Q

NCARDRS - What is this?

A

National Congenital Abnormality and rare Disease registration Service

41
Q

Trisomy 21:

  • Associated with some level of learning disability – …% in mainstream primary school. Cannot predict … pre-birth.
  • Some health conditions are more …
  • Typical life expectancy is …+
A
  • Associated with some level of learning disability – 80% in mainstream primary school. Cannot predict severity pre-birth.
  • Some health conditions are more common
  • Typical life expectancy is 60+
42
Q

Trisomy 21: Parents Understanding

  • Most parents report … experience [Bertrand 2017]
  • …% felt outlook on life more positive
  • Over …% expressed love for their child
  • …% regretted having their child
  • …% of people with Down’s say they enjoy their life [Skotko et al 2011]
A
  • Most parents report positive experience [Bertrand 2017]
  • 79% felt outlook on life more positive
  • Over 99% expressed love for their child
  • 7% regretted having their child
  • 99% of people with Down’s say they enjoy their life [Skotko et al 2011]
43
Q

Condition diagnosed - E.g. Trisomy 21

  • Options
    • Continue
    • Continue and …
    • Termination [medical / surgical] [Trisomy 21: …%]
  • Support
  • Termination under Grounds …
  • There is a substantial risk that if the child were born it would suffer from such physical or mental abnormalities as to be seriously …
A
  • Options
    • Continue
    • Continue and adoption
    • Termination [medical / surgical] [Trisomy 21: 90%]
  • Support
  • Termination under Grounds E
    • There is a substantial risk that if the child were born it would suffer from such physical or mental abnormalities as to be seriously handicapped
44
Q
  • To put termination for fetal anomaly into context – in 2018 there were over 200,000 abortions in England and Wales, of which around …% were under Ground E
A
  • To put termination for fetal anomaly into context – in 2018 there were over 200,000 abortions in England and Wales, of which around 2% were under Ground E
45
Q

Condition diagnosed - such as Trisomy 21

  • Additional Support
    • Antenatal Screening Co-Ordinator / midwife
    • National support groups:
      • Antenatal Results and Choices [ARC],
      • Downs syndrome association [DSA]
      • Soft U.K. [Tri 13 and 18], Unique, Contact-A- Family
    • Meet other parents [Specialist Health Visitor / local groups]
    • Obstetric / neonatal / paediatric /surgical teams
    • Genetic counselling
A
  • Additional Support
    • Antenatal Screening Co-Ordinator / midwife
    • National support groups:
      • Antenatal Results and Choices [ARC],
      • Downs syndrome association [DSA]
      • Soft U.K. [Tri 13 and 18], Unique, Contact-A- Family
    • Meet other parents [Specialist Health Visitor / local groups]
    • Obstetric / neonatal / paediatric /surgical teams
    • Genetic counselling
46
Q

Pre–screening test information: what should we be discussing?

  • Prior to entering a screening programme
  • Tests are …
  • What are we screening for?
  • What the test will …
  • … of tests
  • … results – higher / lower chance
  • Options if … chance result
  • Options if a condition is …
  • Contact for further information
A
  • Prior to entering a screening programme
  • Tests are optional
  • What are we screening for?
  • What the test will not tell you
  • Timing of tests
  • Communicating results – higher / lower chance
  • Options if higher chance result
  • Options if a condition is diagnosed
  • Contact for further information
47
Q

National patient information leaflets: Screening tests for you and your baby

A

National screening leaflets are available – these are all digital now. Take time to look at the leaflet – there is also a video for parents.

Year 2 Medicine (162 decks)

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