Medical procedure was carried out on wrong patient at Hartlepool's main hospital trust

The North Tees and Hartlepool NHS Foundation Trust said an “invasive diagnostic examination” was carried out on the individual.

But staff then realised the request for treatment had been made for the wrong patient.

A spokesman for the trust said it had been a cardiology procedure but would not elaborate any further.

Cardiology is the branch of medicine that deals with disorders of the heart and related blood vessels.

The mix-up, which took place at the end of January, was initially reported as a so-called “never event” and then escalated to a serious incident a few days afterwards.

The trust said the patient in question had been aware of the error, was unharmed and that the correct patient had now had the required investigation.

A spokesman for the trust said: “We can confirm that earlier this year a day-case cardiology procedure was carried out on a patient who did not require this particular diagnostic investigation.

“We have fully apologised to the patient who has suffered no adverse effect from the procedure.”

The trust, which operates hospitals in Stockton and Hartlepool and serves a population of about 400,000 people, would not say how exactly the blunder occurred or what the outcome was of the inquiry that resulted.

The spokesman added: “Our trust culture is to take any such incident very seriously but not to lay blame on individuals.

“We always seek to learn and thoroughly investigate to ensure we develop robust processes to prevent a repeat occurrence.”

The NHS defines serious incidents as where the “potential for learning is so great or the consequences to patients, families and carers, staff or organisations are so significant, that they warrant using additional resources to mount a comprehensive response”.

Meanwhile, never events are events that should be entirely preventable through following and implementing guidance and safety recommendations.

When a never event is recorded by a trust it is intended to act as a red flag to make improvements.

It is unclear where the mix-up took place.