Auditing antenatal diagnoses – what is good practice?

1. Auditing antenatal diagnoses – what is good practice? Sarah Ball, Tim Hutchin, George Gray, Linda Jenkinson, Mary Anne Preece West Midlands Laboratory for Inherited Metabolic Disorders, Birmingham Children’s Hospital

2. Summary • Purpose of antenatal audit • Practice at West Midlands Inherited Metabolic Disorders Laboratory • Audit outcome 1984 – 2005 • Details of 2 inconsistent audits and resultant change in practice • Suggested system for adoption by other laboratories

3. Purpose of antenatal audit (1) • In utero diagnosis of inherited disease: most high risk test for genetic laboratories • Misdiagnosis  loss of a potentially healthy life birth of a child with a painful and crippling disease • Huge financial and social costs of misdiagnosis

4. Purpose of antenatal audit (2) • Laboratory procedures to ensure reliability of test result – minimise pre-analytical, analytical and post-analytical errors • Potential sources of unexpected risks of misdiagnosis: • Genetics of the disease • Expression in utero (biochemical tests) • Technical problems with an established test • Inadequate test validation

5. Purpose of antenatal audit (3) • To monitor the quality of our service we routinely attempt audit on ALL our antenatal diagnoses • Take action if there are anomalies

6. Practice in the West Midlands Inherited Metabolic Disorders Laboratory • West Midlands population is 5.3million • Birth rate of 70000 per year • Since 1984 offered a regional service for co-ordinating prenatal tests for IMDs • Test may be performed: • In-house (DNA/biochemical) • UK biochemistry/molecular genetics network lab • Diagnostic lab abroad • Research lab in UK or abroad • National/international referral centre for some specialist biochemical and DNA tests

7. Prenatal test and audit process (1) At time prenatal testing arranged • letter to clarify • Sample requirement and transport arrangements • Who will dissect sample • Tests to be done and by whom • Identify who will be giving results to the family • Advise that all prenatal tests are audited and recommend early discussion of audit with the family • All prenatal diagnoses are entered in a searchable database (Access)

8. Prenatal test and audit process (2) Analytical process • Receive sample (CVS or AF – cultured or uncultured) • Perform analysis • Results reported and authorised

9. Prenatal test and audit process (3) Final report letter = CHASE 1 • combines all results (eg MCC exclusion, uncultured and cultured CVS/AF results etc) • Requests appropriate audit sample • TOP: skin/placenta • Continuing pregnancy: blood/biochemistry or clinical report of healthy baby • Date of first chase letter recorded on database

10. Prenatal test and audit process (4) Audit sample • Receive audit sample for testing and enter result on data base • Or receive clinical report (acceptable where condition manifest in neonatal period) • Result of audit sample testing or clinical report entered on database • CHASE 2 • If no audit sample received 3 months after the edd write to request appropriate samples

11. Prenatal test and audit process (5) Unaudited prenatal test • If no response after 3 months of second chase letter then prenatal test recorded as unaudited

12. Results of antenatal audit

13. Completed Audits

14. Uncompleted audits No sample received:-

15. Inconsistent case 1 Index case • Baby boy with X-linked adrenoleukodystrophy (X-ALD) by plasma very long chain fatty acid quantification Prenatal test (1995) • VLCFA quantification in uncultured CVS • Predicted unaffected male foetus Audit • Neonatal plasma VLCFA indicated affected status • Audit trail on u-CVS – no evidence for sample swap • Reanalysis of c-CVS – variability of VLCFA levels with passage Conclusion • Result published and change of practice worldwide: VLCFA quantification AND oxidation of VLCFAs • Mutation analysis of ABCD1 gene – now preferred procedure for X-ALD prenatal diagnoses

16. Inconsistent case 1 Index case • Baby boy with X-linked adrenoleukodystrophy (X-ALD) by plasma very long chain fatty acid quantification Prenatal test (1995) • VLCFA quantification in uncultured CVS • Predicted unaffected male foetus Audit • Neonatal plasma VLCFA indicated affected status • Audit trail on u-CVS – no evidence for sample swap • Reanalysis of c-CVS – variability of VLCFA levels with passage Conclusion • Result published and change of practice worldwide: VLCFA quantification AND oxidation of VLCFAs • Mutation analysis of ABCD1 gene – now preferred procedure for X-ALD prenatal diagnoses

17. Inconsistent case 1 Index case • Baby boy with X-linked adrenoleukodystrophy (X-ALD) by plasma very long chain fatty acid quantification Prenatal test (1995) • VLCFA quantification in uncultured CVS • Predicted unaffected male foetus Audit • Neonatal plasma VLCFA indicated affected status • Audit trail on u-CVS – no evidence for sample swap • Reanalysis of c-CVS – variability of VLCFA levels with passage Conclusion • Result published and change of practice worldwide: VLCFA quantification AND oxidation of VLCFAs • Mutation analysis of ABCD1 gene – now preferred procedure for X-ALD prenatal diagnoses

18. Inconsistent case 1 Index case • Baby boy with X-linked adrenoleukodystrophy (X-ALD) by plasma very long chain fatty acid quantification Prenatal test (1995) • VLCFA quantification in uncultured CVS • Predicted unaffected male foetus Audit • Neonatal plasma VLCFA indicated affected status • Audit trail on u-CVS – no evidence for sample swap • Reanalysis of c-CVS – variability of VLCFA levels with passage Conclusion • Result published and change of practice worldwide: VLCFA quantification AND oxidation of VLCFAs • Mutation analysis of ABCD1 gene – now preferred procedure for X-ALD prenatal diagnoses

19. Inconsistent test 2 Index case • Neonatal hypoglycaemia, lactic acidosis • then hypotonia, liver failure, nystagmus and died • Fibroblast phosphoenolpyruvate carboxylasekinase (PEPCK) showed marked deficiency Prenatal test • PEPCK very rare no experience of prenatal testing worldwide • Testing lab agreed to test c-AF cells on research basis only • Parents counselled that experimental procedure • C-AF cell PEPCK within normal limits Audit • Baby born with same symptoms as index case • Fibroblast PEPCK within normal limits • Further studies suggested a possible mtDNA depletion disorder Conclusion • Involvement of PEPCK remains unknown • Availability of information on reliability of test crucial for informed genetic counselling

20. Inconsistent test 2 Index case • Neonatal hypoglycaemia, lactic acidosis • then hypotonia, liver failure, nystagmus and died • Fibroblast phosphoenolpyruvate carboxylasekinase (PEPCK) showed marked deficiency Prenatal test • PEPCK very rare no experience of prenatal testing worldwide • Testing lab agreed to test c-AF cells on research basis only • Parents counselled that experimental procedure • C-AF cell PEPCK within normal limits Audit • Baby born with same symptoms as index case • Fibroblast PEPCK within normal limits • Further studies suggested a possible mtDNA depletion disorder Conclusion • Involvement of PEPCK remains unknown • Availability of information on reliability of test crucial for informed genetic counselling

21. Inconsistent test 2 Index case • Neonatal hypoglycaemia, lactic acidosis • then hypotonia, liver failure, nystagmus and died • Fibroblast phosphoenolpyruvate carboxylasekinase (PEPCK) showed marked deficiency Prenatal test • PEPCK very rare no experience of prenatal testing worldwide • Testing lab agreed to test c-AF cells on research basis only • Parents counselled that experimental procedure • C-AF cell PEPCK within normal limits Audit • Baby born with same symptoms as index case • Fibroblast PEPCK within normal limits • Further studies suggested a possible mtDNA depletion disorder Conclusion • Involvement of PEPCK remains unknown • Availability of information on reliability of test crucial for informed genetic counselling

22. Inconsistent test 2 Index case • Neonatal hypoglycaemia, lactic acidosis • then hypotonia, liver failure, nystagmus and died • Fibroblast phosphoenolpyruvate carboxylasekinase (PEPCK) showed marked deficiency Prenatal test • PEPCK very rare no experience of prenatal testing worldwide • Testing lab agreed to test c-AF cells on research basis only • Parents counselled that experimental procedure • C-AF cell PEPCK within normal limits Audit • Baby born with same symptoms as index case • Fibroblast PEPCK within normal limits • Further studies suggested a possible mtDNA depletion disorder Conclusion • Involvement of PEPCK remains unknown • Availability of information on reliability of test crucial for informed genetic counselling

23. A system for antenatal audit • Database in place for audit • Facilitates running work lists regularly to chase audit gaps • Add data: • Before prenatal test • Final result of prenatal test: date of first chase • Date of second chase (if necessary) • Result of audit

24. Minimum data required for audit database Before prenatal test • Mother’s name • Disease • Date of sampling procedure • Sample type

25. Minimum data required for audit database After prenatal test • Result of diagnostic test • Date of first chase (i.e. final report letter) • Pregnancy continuing or termination of pregnancy

26. Minimum data required for audit database Audit test • If termination of pregnancy: • Foetal skin/placenta • Result consistent or inconsistent • If pregnancy continuing: • Await appropriate sample from baby • Result of biochemistry or DNA analysis on neonatal sample • Result consistent or inconsistent

27. Minimum data required for audit database Second chase • 3 months after live birth expected • If no audit sample or appropriate clinical report • Repeat request for audit sample • If still no reply or no sample after a further 3 months record as unaudited

28. Conclusions (1) • Essential to ensure awareness of audit in clinical team and counsel family before prenatal test performed • Audit is routine • Attempt to audit all prenatal tests • Parents may decline audit specimen • Parents may chose not to be informed of the audit result if TOP

29. Conclusions (2) • Clinical and lab audit is essential to good practice • Our results show value of antenatal audit • Systems are easily set up – high success rate of audit completion • Audit permits evaluation of new methods and checking performance of established methods • Failure to detect technical error (e.g. atypical enzyme deficiency or anomalous mutation test) would mean the same misdiagnosis could be repeated in subsequent pregnancies • Antenatal screening committee document on “Prenatal screening standards and protocols” April 2008 will have a standard on audit of amniocentesis and CVS diagnostic procedures and outcomes of pregnancy

30. What is done in other labs? • What is the current practice in ACC and CMGS laboratories? • Are audits attempted on all antenatal diagnoses, some or none? • If only some, how are they selected?