Transcript 1st and 2nd trimester screening

Problem based learning
Antenatal screening
programme
Factual learning objectives
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What is screening?
NICE guidelines
Maternal screening:
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Haemoglobinopathies
Infectious diseases
Gestational diabetes
Fetal anomaly screening
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Ultrasonography
Downs syndrome screening
Other learning opportunities
and discussion points
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Ethical issues around screening
Explanation skills and problems
Different roles in MDT
Children with disabilities
Communicating risk
What is screening?
‘Screening may be described as the
process of looking at a population
perceived to be at risk from a
condition in an attempt to identify
those at higher risk, in whom some
intervention may be made.’
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Not diagnostic
Looking at general asymptomatic
population
WHO screening criteria
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The condition should be an important one.
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There should be an acceptable treatment.
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Facilities for diagnosis and treatment should be available.
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There should be a recognised latent or early symptomatic
stage.
There should be a suitable test which has few false positives
and few false negatives.
The test or examination should be acceptable.
The cost, including diagnosis and subsequent treatment,
should be economically balanced.
Discussion point - screening
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Advantages of screening
Problems with screening
Issues with this case
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Age of patient
Involvement of partner
Understanding of issues
Screening programme
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In England, run by UK National
Screening committee.
Antenatal:
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Fetal anomaly screening programme
Infectious diseases in pregnancy
Sickle cell and thalassaemia screening
programme
Gestational diabetes
Newborn:
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Newborn and infant physical examination
Newborn blood spot
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Newborn hearing screening
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Counselling
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Mothers should be aware of all options
available to them, including the option
to decline testing
Mothers should be aware of the
benefits and limitations of screening
tests and should understand the
meaning of results to be obtained.
Discussion point –
giving information
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How much information do mothers want?
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How do we give this?
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Who should give it?
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When do we give this?
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Does everyone need the same
information?
Infectious diseases screening
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Who - all women
When - at booking
Why - enable treatment, minimise risk of
transmission
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What - blood tests
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HIV
Hep B
Syphilis
Rubella susceptibility
Haemoglobinopathy screening
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Who:
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When:
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At booking
Why:
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all women in units defined as high prevalence (fetal
prevalence of sickle cell disorder greater than 1.5 per 10,000
pregnancies)
In low risk units to women from high risk origins
For all women inspection of blood indices
Enable treatment, identify neonates at risk
What:
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Blood test for haemoglobinopathy
Red cell indices
Discussion point – ethical issue
of justice and equality
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Is it ethical to offer screening based
on prevalence in an area?
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What about women who are in area
with low prevalence that don’t get
screened?
What about women in a high risk area
but that are personally low risk that get
put through screening process?
Gestational diabetes
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Who:
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body mass index above 30 kg/m2
previous macrosomic baby weighing 4.5 kg or above
previous gestational diabetes
family history of diabetes
family origin with a high prevalence of diabetes South Asian, Black Caribbean, Middle Eastern
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Why:
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What:
identify to enable optimum monitoring and
treatment
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Previous gestational diabetes - early self-monitoring of
blood glucose or oral glucose tolerance test at 16–18
weeks, followed by OGTT at 28 weeks if the first test is
normal
Otherwise - OGTT to test for gestational diabetes at
24–28 weeks
Fetal anomaly screening
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All women should be offered:
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A screening test for Down's syndrome
that meets agreed national standards
An ultrasound scan between 18 – 20
weeks 6 days to check for physical
abnormalities in their unborn baby
Information to help them decide if they
want screening or not
Downs syndrome screening
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Who – all mothers
When – between 10 and 20 weeks
Why – to offer definitive testing and
option for termination if desired
What……
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A detection rate for Down's syndrome of greater than
75% of affected pregnancies with a screen positive
rate of less than 3%.
What…..
According to NICE appropriate tests include:
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from 11 to 13 weeks 6 days - the combined test
 (NT, hCG and PAPP-A)
 Preferred method as gives early diagnosis and only
needs one visit.
 Includes NT scan (done with dating scan) and
bloods.
from 11 to 13 weeks 6 days and 15 to 20 weeks - the
integrated test
 (NT, PAPP-A + hCG, AFP, uE3, inhibin A)
 Need to attend twice for NT scan before 13 weeks
and then for bloods after 15 weeks.
What…..
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from 11 to 13 weeks 6 days and 15 to 20 weeks the serum integrated test
 (PAPP-A + hCG, AFP, uE3, inhibin A)
 Need to attend twice for bloods but does not
include NT scan (used if cannot measure NT e.g.
due to baby position or patient body habitus)
from 15 to 20 weeks - the quadruple test
 (hCG, AFP, uE3, inhibin A)
 Only option for late bookers
Some special cases e.g. NT only for multiple
pregnancies
Then…
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Calculate risk depending on woman’s age and screening
results (need to know gestation to interpret)
Woman's age (years) Risk as a ratio
Below 20
1:1600
20
1:1500
30
1:800
35
1:270
40
1:100
45 and over
1.50 and greater
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% Risk
0.067
0.066
0.125
0.37
1.0
2.0
Categorise as high or low risk and offer invasive diagnostic
testing to high risk. Cut offs:
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1st trimester combined – 1:150
2nd trimester - 1:200
NT alone - 1:250
Discussion point –
communicating risk
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Quantifying risk:
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“Your baby is at high risk of having Downs syndrome”
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“The risk of your baby having Downs syndrome is 0.05”
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“Out of 20 babies, 1 would have Downs syndrome”
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“There is a 5% chance that your baby will have Downs
syndrome”
“There is a 95% chance that your baby won’t have Downs
syndrome”
Relative v absolute risk:
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“Taking the COCP doubles your risk of having a blood clot” v
“Taking the COCP increases your risk of having a blood clot
from 1 in 14000 to 2 in 14000”
“This drug will result in a 34% reduction in the risk of a heart
attack” (88% took drug) v “This drug will result in 1.4%
fewer people having heart attacks” (42% took drug)
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Any questions at this point?
Discussion point to finish –
community orientation
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How do GP, midwife and consultant
work together? What are their
responsibilities?
What supporting services are
available?
Summary
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Screening
NICE guidelines
Offering information and
communicating risk
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Thank you for listening