Problem based learning

Antenatal screening programme

What is screening? NICE guidelines Maternal screening:

Haemoglobinopathies Infectious diseases Gestational diabetes

Fetal anomaly screening Ultrasonography Downs syndrome screening

Factual learning objectives

Other learning opportunities and discussion points

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.’

Not diagnostic Looking at general asymptomatic population

What is screening?

WHO screening criteria

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.

Discussion point - screening

Advantages of screening Problems with screening Issues with this case

Age of patient Involvement of partner Understanding of issues

In England, run by UK National Screening committee.

Antenatal: Fetal anomaly screening programme Infectious diseases in pregnancy Sickle cell and thalassaemia screening programme Gestational diabetes

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

Screening programme

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.

Counselling

Discussion point – giving information

How much information do mothers want?

How do we give this?

Who should give it?

When do we give this?

Does everyone need the same information?

Who - all women When - at booking Why - enable treatment, minimise risk of

transmission What - blood tests

HIV Hep B Syphilis Rubella susceptibility

Infectious diseases screening

Who: 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

When: At booking

Why: Enable treatment, identify neonates at risk

What: Blood test for haemoglobinopathy Red cell indices

Haemoglobinopathy screening

Discussion point – ethical issue of justice and equality

Is it ethical to offer screening based on prevalence in an area?

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?

Who: 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

Why: identify to enable optimum monitoring and treatment

What: 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

Gestational diabetes

All women should be offered: 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

Fetal anomaly screening

Who – all mothers When – between 10 and 20 weeks Why – to offer definitive testing and

option for termination if desired What……

A detection rate for Down's syndrome of greater than 75% of affected pregnancies with a screen positive rate of less than 3%.

Downs syndrome screening

According to NICE appropriate tests include:

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…..

What….. 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

Calculate risk depending on woman’s age and screening results (need to know gestation to interpret)

Woman's age (years) Risk as a ratio % RiskBelow 20 1:1600 0.067 20 1:1500 0.06630 1:800 0.12535 1:270 0.3740 1:100 1.045 and over 1.50 and greater 2.0

Categorise as high or low risk and offer invasive diagnostic testing to high risk. Cut offs:

1st trimester combined – 1:150 2nd trimester - 1:200 NT alone - 1:250

Then…

Discussion point –communicating risk

Quantifying risk: “There is a 5% chance that your baby will have Downs

syndrome” “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: “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)

Any questions at this point?

Discussion point to finish – community orientation

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

What supporting services are available?

Summary

Screening NICE guidelines Offering information and

communicating risk

Thank you for listening