This investigation seeks to identify opportunities and systemic remedies to reduce the risk of wrong site anaesthetic nerve blocks occurring. Anaesthetic nerve blocks are injections to block pain in a specific region of the body.

Please note that this investigation has previously been known as 'wrong site interventions'.

Investigation summary

We were notified of an incident that took place at a specialist NHS orthopaedic centre in 2017. A 69-year-old man undergoing elective surgery on his right ankle had a nerve block administered to his left leg.

The investigation focuses on:

  • The Stop Before You Block process and its use nationally.
  • Specific distractions arising from this particular incident that impacted on the anaesthetic team.

Stop Before You Block is a national patient safety initiative that aims to reduce the incidence of inadvertent wrong-sided nerve block during regional anaesthesia.

Although the investigation and the report focus primarily on wrong site anaesthetic blocks, the findings, safety recommendations and safety observation may be beneficial when considering the development of other national patient safety initiatives.

Safety recommendations

We made two safety recommendations to the Royal College of Anaesthetists as a result of this investigation. We received their response to our recommendations within 90 days of publication of the investigation report.

We recommend that The Royal College of Anaesthetists establishes a specialist working group to evaluate the current practices used to reduce wrong site block incidents. This group should consider how safety initiatives to reduce wrong site blocks can be standardised in anaesthesia training and practice. It is recommended that the specialist working group consider the impact of: the patient’s state of consciousness, changes in a patient’s position and the prevalence of wrong site block incidents compared to the number of blocks administered.

We recommend that The Royal College of Anaesthetists ensures any further work identified by the specialist working group to reduce wrong site block incidents is subject to human factors-based testing and evaluation.


Combined response to both safety recommendations received 7 November 2018:

The Royal College of Anaesthetists welcomes the publication of the Healthcare Safety Investigation Branch’s (HSIB’s) report on Wrong Site Anaesthetic Nerve Block and supports the recommendation made that the College establishes a working party to evaluate current practices with a view to achieving standardisation.

In response, the College and the Association of Anaesthetists, working through the Safe Anaesthesia Liaison Group, will develop a specialist working group with key stakeholders to evaluate current practices with the aim of minimising the incidence of wrong site blocks. The group will also examine the human factors that increase the chances of wrong site block including patient position changes during procedures. The College will then take forward any work recommended by the group and ensure that human factors testing and evaluation form a key element in trialling any new or modified procedures.