Introduction More than half of in-hospital adverse events can be attributed to a surgical discipline. Checklists can effectively decrease errors and adverse events. However, the mechanisms by which checklists lead to increased safety are unclear. This study aimed to assess the number, nature and timing of incidents intercepted by use of the Surgical Patient Safety System (SURPASS) checklist, a patient-specific multidisciplinary checklist that covers the entire surgical patient pathway.

Methods The checklist was implemented in two academic hospitals and four teaching hospitals in the Netherlands. Users of the checklist had three options for each item that was checked: ‘not applicable’, ‘yes’ and ‘intercepted by checklist’. In each hospital, the first 1000 completed checklists were entered into an online central database.

Results In six participating hospitals, 6313 checklists were collected. One or more incidents were intercepted in 2562 checklists (40.6%). In total, 6312 incidents were intercepted. After correction for the number of items and the extent of adherence in each part of the checklist, the number of intercepted incidents was highest in the preoperative and postoperative stages.

Conclusions The checklist intercepts many potentially harmful incidents across all stages of the surgical patient pathway. The majority of incidents were intercepted in the preoperative and postoperative stages of the pathway. The degree to which these incidents would have been intercepted by a single checklist in the operating room only, compared with a checklist for the entire surgical pathway, remains a subject for future study.