Problems with a merged pathology service resulted in blood test results not being received or being inaccurate in north Kent.

Almost 2,500 patients from Medway, Dartford and Gravesham have been told they will need to have new tests after the problems were flagged up.

Some samples were delayed for so long they expired, while 600 were rejected in the first week.

While it is not believed any clinical harm has been done it is being treated as a serious incident and NHS England and NHS Improvement have been informed.

Shared services went live in April with blood sciences centralised in the middle of June, with a laboratory located at Darent Valley hospital.

Papers from the clinical commissioning groups in the area show GPs practices in the area got some results late while others were wrong, there were also reports samples were not kept correctly overnight leading to the red cells breaking down, the Health Service Journal reports.

The laboratory also uses different codes to GPs in Medway, meaning results had to be updated by hand, while issues with email meant some results had to be sent by post which took 10 days.

North Kent Pathology Service (NKPS) spokesman Glyn Oakley said: “North Kent Pathology Service is aware that there have been some delays in processing a number of blood tests and we want to apologise to patients, GP colleagues and other healthcare professionals affected by this.

“Patient safety is our absolute priority, and therefore we are working with Dartford and Gravesham NHS Trust, Medway NHS Foundation Trust, and local NHS commissioners to put things right and minimise any risk to patients.

“We have processes in place to identify all patients who need further tests and ensure that they have, or are being, re-tested. We have been in touch with patients needing repeat tests directly, with those patients undergoing high priority tests contacted first. Patients have responded to our recall and many patients have already been re-tested with their results put on the system for clinicians to review. We have notified patients’ GPs and hospital doctors about the recall and confirmed which of their patients are having tests repeated. A continuing clinical review has not identified any patient harm as a consequence of the delays.

“We have contacted those patients affected by the delay, but we also recognise that reports of delays may worry some patients. We have set up a contact point (01322 428922 and 01322 428664) for people involved in this incident to call with any questions or concerns about their blood tests.”

Chair of the Kent Local Medical Committee Dr Guarav Gupta said the problems had "a much wider effect than just doing some tests again,” with GPs having to dedicate resources to rectifying the problems.