Thousands of cervical smear tests are being rescreened by the East and North Herts Trust after concerns were raised about results.

About 20,000 samples taken from women between July 2013 and March 2014 and tested by the NHS trust’s analysers are being rescreened after the regional screening quality assurance reference centre flagged up concerns about test results it had analysed.

The NHS trust has two members of specialist cytology screening team review cells taken from women to determine whether they are precancerous.

These results are then checked with the quality assurance reference centre.

Nine months ago they raised sufficient concern to suggest an audit should be carried out, despite the results being within the 90 per cent target rate.

These retests have also been carried out by other NHS trusts.

A spokesman for the NHS trust – which oversees the running of Stevenage’s Lister Hospital – said the retesting was a “purely precautionary measure, with the aim of confirming the original results”.

At the time of writing, around 93 per cent of tests had come back and of these less than five per cent of women were invited back for a second test.

The NHS trust’s medical director Jane McCue said: “When we received the report from our quality assurance colleagues, it was right that we erred on the side of caution and reviewed the identified cervical screening tests that were carried out between July 2013 and March 2014.

“The aim was to confirm that the results given to the women involved were right.

“Where we find reasons that some form of follow-up may be needed, we will arrange for this to happen quickly.

“Cervical screening plays a vital role in helping to detect the very few women who may be in the very early stages of developing cancer.

“Early detection is known to help improve chances of any cancer detected being treated successfully, which is why we have acted promptly to ensure that confidence in the quality of our local screening programme is maintained.”