Surgical mistakes: how and why ‘never events’ still happen in hospitals

Surgery is intended to improve health and quality of life. For the vast majority of patients, it does exactly that. However, recent data shows a worrying rise in serious and entirely preventable surgical mistakes in NHS hospitals - errors so significant they are classed as “never events”

These incidents can have life-changing consequences for patients and their families. Understanding how and why surgical mistakes occur is crucial, not only for patient safety, but also for those considering whether they may have grounds for a clinical negligence claim.

What are surgical “never events”?

A never event is defined by the NHS as a serious patient safety incident that is wholly preventable when established safety procedures are followed. In a surgical context, these include:

• Operating on the wrong patient
• Operating on the wrong body part or wrong side
• Removing the wrong organ or tissue
• Leaving surgical instruments or materials inside a patient

These are not minor technical errors. They reflect fundamental failures in identification, consent, communication or surgical checking systems.

A sharp rise in wrong site surgery

New figures obtained through Freedom of Information requests reveal that 661 cases of wrong site surgery occurred in English NHS hospitals between 2020 and 2025 - representing a 46% increase over five years.

Crucially, around 7% of these cases caused serious harm, including permanent injury, loss of organs and infertility.  

Real world examples of surgical mistakes

Recent reporting highlights just how devastating these errors can be. In one case, a patient had both ovaries removed instead of one, resulting in immediate surgical menopause and permanent infertility. This error was recorded as causing severe harm.

Other incidents included:

• Surgery performed on entirely different patients
• Removal or biopsy of the wrong anatomical structure
• Anaesthetic blocks administered at the wrong site

Why do these mistakes still happen?

NHS hospitals use multiple safety systems, including pre operative checklists and patient identification protocols. Despite this, errors continue to occur due to a combination of factors, including:

• Failures in communication within surgical teams
• Time pressures and high workloads
• Inadequate handover procedures
• Human error compounded by systemic weaknesses
• Poor adherence to safety protocols

Healthcare experts have warned that rising demand and staffing pressures may be undermining patient safety unless actively addressed

When does a surgical mistake amount to clinical negligence?

Not every complication following surgery will give rise to a legal claim. However, a surgical mistake may amount to clinical negligence where:

1. The care provided falls below an acceptable standard, and
2. That failure directly causes avoidable harm

Examples include, but are not limited to: 

• Wrong‑site surgery
• Removal of the wrong organ or tissue
• Retained surgical items
• Damage to surrounding organs
• Nerve damage caused by surgical error
• Incorrect or poorly performed surgical technique
• Failure to recognise or respond to complications
• Anaesthetic errors linked to surgery
• Operating without valid informed consent
• Inadequate post‑operative care