Guidance

Reviewing historic SurePath slides

Updated 27 September 2024

The invasive NHS Cervical Screening Programme (CSP) auditing procedures mandates that all individuals diagnosed with cervical cancer:

• have a screening history case review
• are offered the results of their review once it is complete in accordance with the national guidance on duty of candour

This document provides guidance for reviewing historic SurePath slides as part of the auditing process.

SurePath slides

Since the implementation of liquid-based cytology (LBC) into the NHS CSP in 2004, 2 technologies have been approved for use. These are ThinPrep and SurePath.

Before December 2019, reviews were carried out by laboratories routinely reporting the relevant LBC technology, or where they had previously reported that LBC technology.

By December 2019, all cervical screening laboratories in England had implemented high risk (HR) human papillomavirus (HPV) Primary Screening using the ThinPrep LBC technology. SurePath LBC samples were no longer received and assessed for patient care purposes across England from this point onwards.

However, an individual patient’s screening history can contain a mixture of both ThinPrep and SurePath LBC samples. This guidance describes the process for reviewing historic SurePath slides.

Cytology slide reviews

Cervical cytology is subjective and the reasons why abnormal cells may be overlooked during routine screening are well documented. As a result, there is limited educational value for professionals working in laboratories in the review of individual historic slides. However, reviews are essential to individuals diagnosed with cervical cancer to provide them with information on their screening history. Slide reviews also contribute to the overall evaluation of the cervical screening programme.

Review of historical slides

Review of slides where the results have already been reported to the patient is a different activity to that of routine reporting of screening tests for patient management purposes. As a result, the competencies required are different.

Case review takes place in the full knowledge of the original result. This helps to identify learning points around how a cervical cancer may have developed for the NHS CSP.

SurePath slide review network

A national SurePath slide review network has been established, administered by the Screening Quality Assurance Service (SQAS). The network includes laboratory professionals:

• qualified to report SurePath slides (having completed training at an approved NHS CSP training school)
• who have reported SurePath material for direct patient care purposes in the NHS CSP for a minimum of 2 years at a senior level – senior biomedical scientists (BMS) or above

Abnormal slides must be reviewed by a member of staff at consultant grade (consultant BMS or pathologist) and this will be considered the final outcome.

Laboratories employing members of the SurePath slide review network will use their own staff to undertake their own local reviews, unless there is a disproportionate distribution across laboratories that would lead to significant inequity and delays.

The SQAS administration team will distribute reviews for slides requested by laboratories who do not have members of the network within their laboratory. This is to make sure reviewers receive a fair and equitable distribution of material from outside their laboratory footprint. This may be extended to all laboratories depending on the distribution of reviewers.

Second reviews

A second review will be arranged as soon as possible in cases where the review of a slide meets the appropriate criteria and the individual was diagnosed before 1 October 2021.

This second review will be led by an individual within the reviewing laboratory if one is available, otherwise the SQAS administration team will organise an appropriate person to lead it. Please note, the second review should be carried out by a different reviewer to the one at the original reporting laboratory.

Limitations of SurePath reviews

Although it may be possible to identify obvious abnormalities that may have been overlooked when the slide was originally reported, it can be difficult to identify more subtle changes during a review. This is because staff undertaking reviews are no longer routinely assessing SurePath material for direct patient care. As such, the slide review outcome, and feedback to women, should include the following caveat for SurePath slides.

The staff undertaking this review do so in the full knowledge that it is a case of cervical cancer, and in good faith. However, any SurePath cervical cytology material that is reviewed is not one they now routinely assess or have had routine exposure to since at least 2019. This report should not be regarded as reliable for medico-legal purposes. This slide review is not covered by ISO: 15189.

Continuous professional development (CPD)

Staff undertaking ThinPrep and/or SurePath all slide reviews should be active in the NHS CSP and report screening material routinely. Staff undertaking slide reviews are doing so as part of the NHS CSP and this activity will therefore be part of their routine practice and professional appraisal processes.

They should participate in the CPD activities outlined in NHS CSP guidance and meet programme standards. CPD activities to support this aspect of professional practice could include:

• reviewing literature on known reporting pitfalls
• review of local training slide sets where available
• attending slide review training courses where available
• attendance at workshops, including feeding back on slide reviews

Caveats

People continue to develop cervical cancer despite the effectiveness of population-based screening. It is therefore essential to audit all cases of cervical cancer along with those people’s interactions with the NHS CSP and compare with people who do not develop cervical cancer.

Monitoring changes in cervical cancer incidence and mortality rates can help to determine whether the NHS CSP is achieving its objectives. It will not give a complete picture because it cannot assess whether alterations to the programme are affecting the incidence of cervical cancer. Such alterations would include changes to:

• screening technologies
• the ages people are called for testing
• how often people are screened

Nor does it indicate the effectiveness of the NHS CSP if everyone attended when invited, or include individuals who have never had a test.

Now that the NHS CSP uses HPV testing as its primary screening test, audits will enable identification of cervical cancers that develop despite a negative HPV test.