Surgical complications: errors and adverse events.

Complications are a recognized hazard of surgery. The term is confusing; it has multiple meanings, including surgical error and adverse surgical outcomes. I propose the latter two terms are used. Grading of 'complications' is difficult but made easier by grading errors and outcomes separately, though they are not always linked. The exact grades are not established.Error avoidance requires efforts at a personal (surgeon) level, including training, learning and preparation, and at a systems level. Understanding human factors is important.The perspective of patients about adverse outcomes is not well understood. There is evidence that, unsurprisingly, patient perspectives may be different to surgeon perspectives. There are a range of surgeon responses to error and adverse outcomes; many are negative. These need to be understood better in order to protect patients and surgeons in the immediate aftermath and in the potentially prolonged 'recovery time', both for patients and surgeons. Level of evidence: V.