Aim To identify and characterise hazardous conditions in an Emergency Department (ED) using active surveillance.

Methods This study was conducted in an urban, academic, tertiary care medical centre ED with over 45 000 annual adult visits. Trained research assistants interviewed care givers at the discharge of a systematically sampled group of patient visits across all shifts and days of the week. Care givers were asked to describe any part of the patient's care that they considered to be ‘not ideal.’ Reports were categorised by the segment of emergency care in which the event occurred and by a broad event category and specific event type. The occurrence of harm was also determined.

Results Surveillance was conducted for 656 h with 487 visits sampled, representing 15% of total visits. A total of 1180 care giver interviews were completed (29 declines), generating 210 non-duplicative event reports for 153 visits. Thirty-two per cent of the visits had at least one non-ideal care event. Segments of care with the highest percentage of events were: Diagnostic Testing (29%), Disposition (21%), Evaluation (18%) and Treatment (14%). Process-related delays were the most frequently reported events within the categories of medication delivery (53%), laboratory testing (88%) and radiology testing (79%). Fourteen (7%) of the reported events were associated with patient harm.

Conclusions A significant number of non-ideal care events occurred during ED visits and involved failures in medication delivery, radiology testing and laboratory testing processes, and resulted in delays and patient harm.