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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
* NT – nuchal translucency * The NT scan is not used after ... weeks,
* NT – nuchal translucency * The NT scan is not used after **14** weeks,
26
The quad test is a blood test measuring **...** markers in the blood.
The quad test is a blood test measuring **4** markers in the blood.
27
_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
* UE3 unconjugated estriol – **placental** hormone * AFP alpha fetoprotein – **protein** from **fetus** * **Inhibin** A placental hormone * **BHCG** beta human chorionic gonadotrophin- placental hormone
28
_Quad test : Detection rates_ * DR is similar to singleton pregnancy but the SPR doubles. * T 21 - DR is ...%, Screen positive rate is ...%
* DR is similar to singleton pregnancy but the SPR doubles. * T 21 - DR is **80**%, Screen positive rate is **2.5-3.5**%
29
_Quad test : Detection rates : Twins_ * Monochorionic twins: * DR ...% SPR ..% * Dichorionic twins: * DR ...-...% SPR ...%
* 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
* 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
* 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
_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]
* 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
_Prenatal diagnosis / Diagnostic invasive test_ * Chorionic Villus Sampling CVS ...+ weeks * Amniocentesis ...+ weeks to term * Around ...-...% risk of miscarriage * [higher in ...]
* Chorionic Villus Sampling CVS **11**+ weeks * Amniocentesis **15**+ weeks to term * Around **0.5 -1**% risk of miscarriage * [higher in **twins**]
33
_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
* 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
Combined Screen Test / NIPT
* 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
_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
* **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
_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
* 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
_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
* 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
_11conditions screened at mid trimester scan_
39
_11 conditions screened at mid trimester scan are:_
* 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
NCARDRS - What is this?
**National Congenital Abnormality and rare Disease registration Service**
41
_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 ...+
* 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
_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]
* 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
_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 ...
* 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
* 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
* 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
_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
* 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
_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
* 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
_National patient information leaflets: Screening tests for you and your baby_
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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