Every undesired outcome of care is a complication, irrespective of its cause. Not every complication is an adverse event, because complications can be related to the underlying disease or comorbidity. Of all adverse events almost half is preventable [2]. Besides the physical and emotional damage adverse events generate considerable health care costs.

The landmark report in patient safety awareness suggests that 44–98 thousand deaths every year resulted directly from medical errors that could, and should have been prevented [1]. According to a systematic review of eight studies covering nearly 75,000 medical records in various high income countries, an adverse event (AE) occurs in 1 out of 11 patients (9.2 %) in hospital. More than half of AEs are associated with surgery. Many adverse events take place in the operating room and on the ward. Complex environments such as the Emergency Room and the Intensive Care Unit contribute less to adverse events (3.0 % and 3.1 %, respectively) [2] Medication related events are relatively frequent with 15.1 % of all in-hospital adverse events.

In the decade since the IOM report, thousands of scientific articles have been written about this subject, illustrating the raised awareness regarding preventable medical errors and patient harm [3]. Patient safety publications increased from 59 to 164 articles per 100,000 on MEDLINE [4]. Not only has awareness increased, but there has been a change in safety culture. The way we think about surgical safety has changed for the better, and promising interventions such as the use of operative checklists, have been studied extensively, and are routine in daily practice in many hospitals.

Errors and adverse events are not always easily to distinguish from risks inherent to medical treatment. This causes confusion and incomparability of published data with different underlying definitions. Risks of interventions or surgical procedures can never be eliminated completely. Doctor and patient together must discuss and weigh expected effects of a procedure against its risks.

Process deviations involving a surgical patient are seen more outside than inside the operating room [5]. A surgical patient goes through an admission pathway with different locations: from the ward (or admission unit or daycare facility) to the holding area, to the operating room, to the recovery room (or ICU), to the surgical ward until discharge. From observations of the entire surgical pathway of 170 patients is became apparent that over 50 % of process deviations occur outside the operating room, in the pre- and postoperative phase of the pathway (Fig. 25.2) [5].

Many of these deviations can and must be corrected before the patient enters the operating room, and not just before start of surgery. When essential checks are performed in the operating room at first, this can lead to unnecessary risks. A patient who was already under anesthesia when at team time-out in the operating room it was discovered that a prosthetic knee implant was not available in her size. She had to return to the ward without being operated. Indeed the problem had been discovered before the surgical incision was made, but the patient underwent needless anesthesia, because the problem was not intercepted earlier. This case must be judged as a preventable error, leading to needless anesthesia and postponement of surgery. This postponement is associated with extra costs and a considerable psychological burden for the patient. Moreover, in similar situations there is a considerable risk of the alternative: one decides to go through with another prosthesis size, as the first step (going into surgery) has been made, leading potentially to suboptimal results for the patient. These risks can be prevented by early intervention, for example by a check of necessary equipment and materials on the day before surgery or the morning of surgery. The patient is not safe even after leaving the operating room, as many adverse events happen in the postoperative phase. Previous observational data have found that in 22 % of patients the postoperative instructions are incomplete. Moreover, 11 % of patients are discharged without home medication prescriptions [5].

A process is a sequence of coherent activities. If a process takes place in a complex environment, memory and situational awareness can be aided by the use of a checklist (see Box 25.1). The surgical process comprises the sequence of coherent activities of a patient undergoing surgery, from (pre)admission to discharge. It is counterproductive to have separate checklists, each covering an isolated part of the same process. This creates a checklists’ jungle with different checklists used side by side: at start of anesthesia equipment, maintenance of medical devices, use of laparoscopic equipment, sterilization of instruments, counting of sponges, needles and instruments, preparation and use of medication, communication at transfer moments, and so on. General overview of the process, of what needs to be done at what time and who is responsible, is subsequently lost.

In this chapter we learn about adequate and integrated use of a checklist. A team can work together with a checklist in hand and perform necessary process checks as a team. This chapter however focuses on the role of checklist use in situations where there is not clearly a team present, but multiple individuals have a role within the process chain and are thereby links in the chain. Background knowledge is needed to understand why checklist use is necessary in situations where multiple individual tasks are part of the surgical process chain. That knowledge is discussed.