Auditing perioperative mortality.

An audit of mortality following operation was performed over ten years classifying deaths into those that were 'expected' and 'unexpected'. 'Unexpected' deaths were defined as those in which, after careful consideration of the prevailing clinical circumstances at the time of operation, the probability of death following operation was felt to be low. This definition is a more helpful assessment of surgical performance than overall perioperative mortality as it highlights cases where improvements in surgical management might be achieved. In audits involving surgical mortality, the classification of deaths into 'expected' and 'unexpected' is recommended.