Medical misdiagnosis claims: what do you need to prove?

A wrong diagnosis is not always negligence

Diagnosis can involve uncertainty, and different conditions can cause similar symptoms. A diagnosis that later proves wrong is not automatically negligent. The assessment asks whether a reasonably competent clinician should have reached a different conclusion or taken further steps with the information available at the time.

Those steps might include examining the patient, considering alternative diagnoses, arranging tests, referring to a specialist or giving clear advice about when to return if symptoms change.

The two issues a claim must establish

First, independent evidence must usually show that the diagnostic process fell below a reasonable standard. This is often described as breach of duty.

Second, the failure must have caused avoidable harm. This is known as causation. It may involve showing that earlier diagnosis would probably have led to different treatment, a better outcome, less invasive treatment or a shorter period of pain and illness.

Examples of diagnostic failures

Potential concerns depend on the facts and may occur in primary care, hospital departments, emergency care, radiology or pathology.

• Important symptoms or examination findings not investigated
• Abnormal blood, scan or pathology results not acted upon
• A test or image interpreted unreasonably
• Failure to reconsider a diagnosis when symptoms continued or worsened
• An unreasonable delay in referral or follow-up

Records and expert evidence

The records may show what symptoms were reported, what clinicians observed, which possible diagnoses were considered and how results were handled. Referral letters, imaging, pathology, prescriptions and later treatment records can help reconstruct what happened.

Independent experts normally compare the actual care with reasonable practice and explain whether an earlier correct diagnosis would probably have made a material difference. A clear personal chronology can help identify the relevant records and sequence of events.

Starting an enquiry

You do not need to know the precise medical error before asking for advice. Provide the main dates, the diagnosis originally given, the later diagnosis and how the delay or error affected you. Time limits can be complex, so it is sensible to seek individual advice promptly.