Problem based learning

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What is screening?
NICE guidelines
Maternal screening:
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Haemoglobinopathies
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Infectious diseases
Gestational diabetes
Fetal anomaly screening
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Ultrasonography
Downs syndrome screening

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Ethical issues around screening
Explanation skills and problems
Different roles in MDT
Children with disabilities
Communicating risk

‘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

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The condition should be an important one.
There should be an acceptable treatment.
Facilities for diagnosis and treatment should be available.
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.

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Advantages of screening
Problems with screening
Issues with this case
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Age of patient
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Involvement of partner
Understanding of issues

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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
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Newborn:
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Newborn and infant physical examination
Newborn blood spot
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Newborn hearing screening

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Mothers should be aware of all options available to them, including the option to decline testing
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Mothers should be aware of the benefits and limitations of screening tests and should understand the meaning of results to be obtained.

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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?

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Who all women
When at booking
Why enable treatment, minimise risk of transmission
What blood tests
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HIV
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Hep B
Syphilis
Rubella susceptibility

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Who:
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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
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When:
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At booking
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Why:
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Enable treatment, identify neonates at risk
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What:
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Blood test for haemoglobinopathy
Red cell indices

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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?
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What about women in a high risk area but that are personally low risk that get put through screening process?

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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: identify to enable optimum monitoring and treatment
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What:
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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

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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
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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

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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%.

According to NICE appropriate tests include:
 from 11 to 13 weeks 6 days the combined test
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(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
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(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.

 from 11 to 13 weeks 6 days and 15 to 20 weeks the serum integrated test
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(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
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(hCG, AFP, uE3, inhibin A)
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Only option for late bookers
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Some special cases e.g. NT only for multiple pregnancies

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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
35
40
45 and over
1:800
1:270
1:100
1.50 and greater
% Risk
0.067
0.066
0.125
0.37
1.0
2.0
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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
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2 nd trimester - 1:200
NT alone - 1:250

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Quantifying risk:
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“There is a 5% chance that your baby will have Downs syndrome”
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“Your baby is at high risk of having Downs syndrome”
“The risk of your baby having Downs syndrome is 0.05”
“Out of 20 babies, 1 would 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”
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“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?

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How do GP, midwife and consultant work together? What are their responsibilities?
What supporting services are available?

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Screening
NICE guidelines
Offering information and communicating risk

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Thank you for listening