Guidance

Governance, quality assurance and accreditation

Updated 10 October 2024

Applies to England

1. Governance

NHS population screening explained sets out the general principles of screening.

The UK National Screening Committee (UK NSC) makes recommendations on screening policy.

NHS England and Improvement (NHSEI) is responsible for the commissioning and operational delivery of the national screening programmes. The Office for Health Promotion (OHP), part of the Department of Health and Social Care (DHSC), supports the development of screening policy based on UK NSC recommendations.

Commissioners and providers should refer to the Sickle cell and thalassaemia (SCT) screening pathway requirements specification that provides an overview of SCT screening by describing what should happen at each stage.

2. Accreditation

Laboratories offering screening including those performing DNA confirmations and/or PND for the NHS Sickle Cell and Thalassaemia (SCT) Screening Programme must:

• be accredited by the UK Accreditation Service (UKAS) to ISO Medical laboratories – requirements for quality and competence (ISO 15189:2012)

• participate in external quality assurance (EQA) schemes accredited to ISO Conformity assessment General requirements for proficiency testing schemes (ISO 17043:2010)

• use ISO 15189:2012 accredited reference laboratories.
• have a viable contingency plan for screening, to continue the provision of SCT screening in the event of any failures to the laboratory service
• include an annual vertical audit of an antenatal screening sample in its laboratory audit schedule

The annual vertical audit should randomly select a confirmed screen positive sample and include arrival and receipt of the antenatal screening sample at the laboratory. It should also include acknowledgment of screen positive results by clinical services.

The United Kingdom Accreditation Service (UKAS) looks at ISO 15189:2012 and the screening requirements on behalf of the screening quality assurance service (SQAS) and the NHS SCT Screening programme.

In some cases, responsibility for analysis and reporting of results may be shared between 2 laboratories. This is usually where a low prevalence laboratory relies on the expertise of a high prevalence laboratory for sickle cell screening.

2.1 Models for SCT screening delivery and level of UKAS assessment required

The list below outlines various models that might exist where 2 laboratories are involved and defines the level of UKAS assessment required.

Delivery model 1

Laboratory A performs FBC and reports FBC and HPLC results.

Laboratory B performs HPLC.

Level of UKAS assessment required for:

• laboratory A: ISO15189 + screening requirements
• laboratory B: ISO15189

Delivery model 2

Laboratory A performs FBC and reports results.

Laboratory B performs HPLC and reports results.

Level of UKAS assessment required for laboratory A and B: ISO15189 + screening requirements.

Delivery model 3

Laboratory A books in sample and sends to laboratory B.

Laboratory B performs FBC, HPLC and reports results.

Level of UKAS assessment required for:

• laboratory A: ISO15189
• laboratory B: ISO15189 + screening requirements

Delivery model 4

Laboratory A performs FBC and decides based on the FOQ which samples to send to laboratory B.

Laboratory B performs HPLC and reports results.

Level of UKAS assessment required for laboratory A and B: ISO15189 + screening requirements.

3. Carrying out a look back with particular reference to HbA₂

A lookback is a review of screening records to identify individuals harmed or at risk of harm as a result of a screening safety incident or serious incident. Look backs or case reviews may also be carried out as part of fact finding to establish if there has been a screening incident. Look backs may result in a patient notification exercise or recall.

If your external quality control shows the HbA₂ is out of consensus then a look back exercise must be considered. HbA₂ values which fall below consensus are of particular concern as in this situation β thalassaemia carriers may have been missed.

The following steps are a guide to carrying out a look back exercise. While not mathematically exact, the calculation given is suitable for this purpose. It should be noted that every situation is unique and you may wish to obtain advice from your external quality control provider and the national NHS SCT Screening Programme.

If a look back exercise is required, report this as a suspected safety incident in accordance with Managing safety incidents in NHS screening programmes.

This means informing the regional SQAS and the host organisation responsible for the laboratory, in addition to relevant clinical teams (including midwifery).

The accountable organisation will need to decide if Duty of Candour applies.

3.1 Method

1. Identify the point in time the results were last within consensus.

2. The look back must review patient results from that time point until results are proven to be back in consensus. If results are not yet proven to be within consensus then the actions described should continue prospectively.

3. All patient results must be reviewed. However, the following formula will help identify patients requiring more stringent scrutiny and possible recall:

Discrepancy value = consensus HbA₂ minus HbA₂ obtained by your laboratory

Patients requiring stringent review = HbA₂ action value (3.5%) minus your calculated discrepancy value

For example, if consensus = 3.6% and obtained = 3.2% then the discrepancy value would be 3.6 minus 3.2 = 0.4%. In this scenario all patients with an HbA₂ greater than or equal to 3.1% from the time the results were last within consensus should be carefully reviewed.

1. Patients with an HbA₂ greater than the value identified using the above formula and with an MCH less than 27pg not already identified as a β thalassaemia carrier, should be recalled and retested.

2. Patients with an MCH greater than 27pg and with an HbA₂ which would have been greater than 4.0% when the discrepancy value identified using the above formula is added to the original result obtained should be recalled and retested.

3. All other patients do not need recalling or retesting.

4. Guidelines for analysing liquid capillary blood samples

This service should be seen as a special ‘on-demand’ service to alleviate parental anxiety and not as a failsafe or substitute for the newborn blood spot (NBS) screening programme, nor to gain a more rapid entry into clinical care. If local arrangements can be implemented to obtain fast track results from the routine NBS screening programme, then this approach should be encouraged. Laboratories that perform second-line testing for the NHS NBS Screening Programme would already satisfy most of these criteria.

Laboratory tests may be requested on newborn babies for clinical reasons but these guidelines have been developed specifically for babies born to known high risk biological parents. To be a ‘1 in 4’ high risk pregnancy, the haemoglobinopathy results must be known on both biological parents. Specimens taken for other clinical diagnostic purposes fall outside these guidelines, although the requester may want to assure themselves that the laboratory has sufficient competence and expertise to analyse specimens from newborns.

1. The analytical technique for initial testing of the capillary specimen and the second line test must be appropriate for specimens from the newborn period. Some analytical protocols and instruments are designed for testing adult blood and are not optimal for newborns.

2. The laboratory must participate in an appropriate external quality assurance (EQA) scheme that assesses the analysis and interpretation of results from newborn specimens. UK NEQAS provides suitable quality control specimens for this work.

3. Samples must be transported to the analysing laboratory in a reliable and swift manner, using a courier service if the specimen has to be referred, rather than risking delays using the postal service.

4. Both biological parents’ results must be reviewed before reporting the result of the liquid capillary sample. Since this is a service for pregnancies known to be at a 1 in 4 risk of a significant haemoglobinopathy, the requester must record the results of both biological parents on the request form.

5. The laboratory analysing the liquid specimen is responsible for notifying the newborn screening laboratory of the result. There must be documented local systems in place for this process. Any discrepancy between the 2 results should be investigated rapidly at local level by both laboratories and reported to the NHS SCT Screening Programme and regional team within one week of the discrepancy being detected.

6. Laboratories offering this service must collate data for audit purposes on the number of specimens tested, turnaround times and consistency with newborn screening results.

7. If the results from the liquid capillary specimen and the NHS NBS Screening Programme are in accord with each other, then a further confirmatory specimen is not needed.

8. The laboratory must have standard operating procedures (SOPs) for the analytical methods and the rapid local reporting processes to the relevant healthcare professionals for the capillary specimen result. The SOPs must include senior level checking of analytical results before reporting and follow-up of the subsequent NBS screening result.

9. A mother and baby who are ready to be sent home should not be kept in hospital awaiting the results of these tests.

10. The laboratory must be accredited as per NHS SCT Screening Programme requirements.

5. Screening support service

Laboratories may have questions about screening policy or interpretation of results that cannot be answered easily by reference to this handbook or textbooks. Oxford University Hospitals NHS Trust provides a support service for screening laboratories via designated telephone helplines and secure email.

The national SCT screening programme commissions this service, which supports both antenatal and newborn screening inquiries.

Telephone: 01865 572 769

Email: SCTlab.support@ouh.nhs.uk

6. Useful organisations and websites

For more information, see:

• the British Committee for Standards in Haematology (BCSH)

• SCT screening e-learning modules for health care professionals and laboratory staff

• NHS.UK information on SCT screening

• the SCT Association of Nurses, Midwives and Allied Professionals (STANMAP), which can be contacted for details of local specialist SCT centres.