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Screening for fetal Down’s Syndrome –

Screening for fetal Down’s Syndrome –. Improving efficacy and efficiency. Review of current service performance Drivers for change Configuration of future service New information and new markers Target performance. Conditions screened for…. Downs Syndrome Neural tube defects

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Screening for fetal Down’s Syndrome –

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  1. Screening for fetal Down’s Syndrome – Improving efficacy and efficiency

  2. Review of current service performance • Drivers for change • Configuration of future service • New information and new markers • Target performance

  3. Conditions screened for…. • Downs Syndrome • Neural tube defects • Edwards Syndrome

  4. Second trimester performance in South East Scotland 1996 – 2005 • Uptake 75% • ‘Detection rate’ 66% • False positive rate 5.4%

  5. Second trimester performance in South East Scotland 1996 – 2005 • 64 (34.2%) missed cases • 50% of all screened cases with maternal age <35yrs missed • 43 amniocentesis performed to diagnose 1 case of Down’s Syndrome

  6. Review of current service performance • Drivers for change • Configuration of future service • New information and new markers • Target performance

  7. UK wide…… • UK Screening Committee 2001 Numerous publications • First and second trimester antenatal screening for Down’s Syndrome: the results of Serum, Urine and Ultrasound Screening Study (SURUSS) 2003 • Antenatal Care: routine care for the healthy pregnant woman. NICE 2003 • Down’s Serum Screening Quality Assurance Support Service (DQASS) 2004

  8. In Scotland…. • CUBS screening for Down’s Syndrome in the 1st trimester: a Scottish multicentre study. JA Crossley et al 2002 BJOG 109 p 667 • Health Technology Assessment Report 5 March 2004 Routine ultrasound scanning before 24 weeks of pregnancy • Quality Improvement Scotland Clinical Standards October 2005 Pregnancy and Newborn Screening • CEL 31(2008) Changes to Pregnancy and Newborn Screening Programmes

  9. UK Screening Committee bench mark targets….. • >75% detection rate for a <3% false positive rate by April 2007 • >90% detection rate for a <2% false positive rate by April 2010

  10. Review of current service performance • Drivers for change • Configuration of future service • New information and new markers • Target performance

  11. Changes being made to meet new targets and standards • Laboratory service on course for central funding from 1/4/10 • Laboratory service to be provided from 2 laboratories - Glasgow (Yorkhill) and Edinburgh ( Western General Hospital) • First trimester screen for the majority (85%) • Enhanced second trimester service (15%) • Changing action limit to a higher risk value eg 1:200 or 1:150 • Staff training and revision of patient information leaflet

  12. Screening Labs Aberdeen Grampian (4.5K) Orkney Shetland Dundee Tayside (2.6K) Edinburgh Borders (10K) Fife Lothian Glasgow Ayrshire & Arran (20K) Argyll & Clyde Dumfries/Galloway Forth Valley Greater Glasgow Highland Lanarkshire Western Isles

  13. Review of current service performance • Drivers for change • Configuration of future service • New information and new markers • Target performance

  14. Screening for Neural Tube Defect using maternal serum AFP Maternal serum AFP measurement will cease to be used to provide the screening service for neural tube defects However • There will be an NTD only request form • The lab will continue to report AFP MOM and indication of risk with 2nd trimester results

  15. Markers of fetal Down’s Syndrome Maternal age plus……. First Trimester (11 weeks - 13 weeks and 6 days) • Nuchal Translucency (↑) • Free beta human chorionic gonadotrophin (↑) • Pregnancy-associated plasma protein A (↓) Second Trimester (15 weeks - 20 weeks and 0 days) • Intact human chorionic gonadotrophin (↑) • Inhibin A (↑) • Unconjugated oestriol (↓) • Alphafetoprotein (↓)

  16. Request information • Demographics • Measure of gestation eg CRL/HC and date or EDD • Current smoker • Ethinic origin • Previous affected pregnancy, parenteral history • Nuchal translucency and ‘sonographer’ ID • Singleton/multiple pregnancy • Maternal weight • Assisted conception

  17. unaffected Down’s Syndrome Marker

  18. Down’s Syndrome unaffected 1 2 Marker

  19. Down’s Syndrome unaffected 1 2 Marker

  20. Unaffected Down’s Syndrome 1 2 Marker

  21. Down’s Syndrome unaffected 1 2 Marker

  22. Importance of accurate dating Dr Trish Chudleigh 2009

  23. CRL conversion 8.052√ (CRL x 1.037) + 23.73 = gestation (days) Robinson HP, Fleming JE,1975 BJOG vol 82; pp702 - 710 http://fetalanomaly.screening.nhs.uk/programmestatements

  24. Laboratory standards • Daily internal quality control • Monthly external quality assessment • CPA Accreditation • 6 monthly data submission to DQASS • Minimum annual work load • Licensed risk calculation software • Target 3 day turn around time • Consultant grade staff heading the service

  25. Nuchal Translucency • Measurement performed between 11 weeks 0 days and 13 weeks 6 days • Nuchal translucency measured in mm performed routinely on the same day as the blood sample • Unique ‘sonographer’ ID number • Regular review of operator bias eg DQASS

  26. First trimester effects PAPP-A ↓ 20% Free βhcg → NT → Second trimester effects Total hcg ↓ 18% Inhibin A ↑62% AFP → UE3 → ‘Are you a current smoker’?

  27. Demographics

  28. Bar coding the CHI number • Bar coded CHI on the request form • Label trace software • http://www.quicktrace.co.uk/labtr.html

  29. Sample transport and transit times • Postal service/ courier • Requirements may differ between 1st and 2nd trimester • Maximum transit time - 3 days for whole blood • Implications for 4 day holidays and samples taken on Thursday • Stability of markers in whole blood and serum may be different

  30. Twin Pregnancy • NT only - but may change http://fetalanomaly.screening.nhs.uk/publicationsandleaflets

  31. Review of current service performance • Drivers for change • Configuration of future service • New information and new markers • Target performance

  32. Assuming 10,000 screens annually of which 20 are Downs Syndrome pregnancies……

  33. Down’s Syndrome unaffected 1 2 Marker

  34. Team Work • Midwives • Sonographers • Obstetricians • Radiologists • Radiographers • Public Health Consultants • Cytogeneticists • Clerical staff • Biomedical scientists • Clinical Scientists • IT support • Reagent Manufacturers • Software Suppliers • Engineer support for scanners and analysers • etc

  35. http://www.healthscotland.com/topics/health/screening/pregnancynewborn.aspxhttp://www.healthscotland.com/topics/health/screening/pregnancynewborn.aspx http://fetalanomaly.screening.nhs.uk/

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