Guidelines and Standards for antenatal microbiology screening

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Guidelines and Standards for antenatal
microbiology screening

• Elizabeth Boxall
• Health Protection Agency
• West Midlands Public Health Laboratory
• Heartlands Hospital, Birmingham

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Infections screened for

• Immunity to Rubella
• Infection with Syphilis
• Infection with Hepatitis B
• Infection with HIV
• Purpose of Screening
• To offer interventions to prevent mother to baby
  transmission of infection in current or future
  pregnancies

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Screening for Infectious Diseases in Pregnancy
(Standards to support the UK A/N screening
programme- August 2003)

• Generic protocols and systems in place to
  deliver and monitor programme
• Managerial ownership and lines of
  responsibility
• Staff trained to offer information advice and
  support
• Antenatal Clinic responsibilities and standards
• Laboratory standards general and organism
  specific

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Screening for Infectious Diseases in
PregnancyLaboratory Standards - generic

• Laboratories should already be performing a
  significant number of tests routinely before
  taking on antenatal screening. (2003 suggested
  1,000 tests)
• Laboratories should be participating in external
  QA (NEQAS)
• Single sample testing
• No report till significant results are confirmed
  on initial sample
• All screening laboratories have timely access to
  confirmatory testing
• Second sample for confirmation of test result and
  correct patient identity
• Referral pathways
• Collection of surveillance information

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Screening for Infectious Diseases in
PregnancyLaboratory Standards disease specific

• Rubella
• Quantitative assay cut off 10IU/ml
• Specificity gt99
• Negative or equivocal results retested with
  second assay
• Reports state antibody detected or not
  detected rather than immune or susceptible
• Screening tests NOT for contacts or rashes in
  pregnancy

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Screening for Infectious Diseases in
PregnancyLaboratory Standards disease specific

• Syphilis
• Use PHLS syphilis screening algorithm. First
  test by EIA.
• Confirm with second test using different
  methodology reduces false positive rate
  timely confirmatory testing to ensure that
• All reactive women referred to GUM to include
  antibiotic treatment and follow up of mother
  this referral to be before 18 weeks for maximum
  effect of intervention
• Partner and older children testing
• Arrangements for serological follow-up of the baby

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Screening for Infectious Diseases in
PregnancyLaboratory Standards disease specific

• Hepatitis B
• Sensitivity and specificity gt99
• Initially reactive samples confirmed by
  neutralisation refer to another laboratory if
  not available in-house
• Hepatitis B confirmation includes HBeAg AntiHBe
  and AntiHBc IgM to identify likely infectivity
  status and acute infections the results of
  these tests determine the prophylaxis for the
  baby
• Second sample for confirmation of source patient

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Standards for antenatal screening for hepatitis
B- Implementation of infant vaccination programme

• Local arrangements to ensure that women have test
  results explained to them
• Access to verbal and written information to
  support women found positive(different languages)
• 100 of at risk infants will receive first dose
  of vaccine within 48hrs of birth
• Infants born to most infectious mothers will
  receive hepatitis B immune globulin within 48hrs
• 100 of infants will receive a full course of
  vaccine 0,1,2, 12months with a blood test at 12
  months for HBsAg
• Breast feeding should not be discouraged

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Screening for Infectious Diseases in
PregnancyLaboratory Standards disease specific

• HIV
• Sensitivity and specificity gt99
• Re-test then send to confirmatory laboratory
  (laboratories within the HPA HIV Laboratory
  Diagnosis Forum) for assay by 2 further HIV
  assays
• Second sample for confirmation of source patient
• Woman referred for specialist HIV treatment
  antiretroviral treatment to reduce risk of mother
  to baby transmission. Discussion about management
  of delivery/breast feeding etc
• Partner and older children testing

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Screening for Infectious Diseases in
PregnancyLaboratory Standards Present and
Future

• What the NBS currently provides to HPA
  surveillance on a monthly basis
• Numbers initially reactive, repeat reactive and
  confirmed positive for every assay
• Numbers positive for HBV, HIV, Syphilis and
  number not immune to rubella
• Ongoing comparison of results in previous years

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Screening for Infectious Diseases in
PregnancyLaboratory Standards Present and
Future

• Collaborations between the Health Protection
  Agency and the National Blood Service to validate
  assays as suitable for donor and antenatal
  screening
• For information about the sensitivity and
  specificity of assays look in-
• http//www.hpa-midas.org.uk/reports/

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Screening for Infectious Diseases in
PregnancyLaboratory Standards Current/Future
Planning

• National Screening Committee currently reviewing
  all antenatal infectious disease screening
  programmes
• Laboratory standards group reviewing current
  guidelines
• Laboratory survey of current practice and
  national mapping exercise to see how services are
  currently being delivered.
• New Standards from these groups later in 2009
• Future SLAs will have to be to new standards

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Screening for Infectious Diseases in
PregnancyLaboratory Standards ?future still
in evolution

• Higher level of minimum tests
• Laboratory to have consultant level supervision
  of work and input to clinical outcomes, advice
  and follow-up
• Confirmatory testing in-house to avoid delays
  in reporting
• Second samples tested by the same laboratory to
  ensure continuity
• Storage of samples for 2 years

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Screening for Infectious Diseases in
PregnancyFuture

• As this is a National Screening Programme with
  outcomes for those individuals there is a need
  to performance monitor and collect surveillance
  data which is used to influence future policies.
• National Antenatal screening request form with
  minimum data set for surveillance
• As well as patient identifiers name, date of
  birth, NHS number, hospital unit number, good
  quality ethnic origin data and information on
  parity
• Antenatal screening laboratories subject to
  higher level of quality assurance monitoring

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Screening for Infectious Diseases in
PregnancyLaboratory Standards Future data
collection

• National Antenatal screening request form
• Minimum dataset and regular quarterly reports to
  HPA on
• Number booked
• Number offered testing
• Number accepting testing for each infection
• Numbers positive for HBV, HIV, Syphilis
• Number not immune to rubella
• Parity and ethnic origin data on all (examples to
  follow)

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Screening for Infectious Diseases in Pregnancy
Summary - Future

• Request form likely to be compatible with other
  antenatal screening programmes
• QA/QC schemes specific for the antenatal
  screening programmes
• More joined up primary screening and confirmatory
  testing
• More active follow up and audit of outcomes
• Higher demands on screening laboratories for
  screening and outcome data