RESUMEN
INTRODUCTION: The adverse events (AE) in hospitalized patients occur with increasing frequency due to the increase in complexity of medical care, which implies a greater risk of committing a human error inherent to the care, constituting a serious threat to the safety of the patient. MATERIAL AND METHODS: Cross-sectional study, including patients older than 16years, with hospital stay longer than 24h and discharge from the general surgery service, patients treated in emergency observation units or other hospital services were not considered. AE were identified, classified by cause according to the essential actions for patient safety (EAPS), and compliance with the EAPS was verified. RESULTS: 352 clinical records were reviewed, 61 (17%) were positive on screening. Of the positives, 66% resulted in AE (47 cases). The prevalence of AE was 13%. The AE were: 40% related to procedures; 39% with infections; 17% with medication; 4% with patient identification. The EAPS with the best rating was EAPS5 and the lowest rating was EAPS4. The night shifts with the greatest opportunity area, only with 40% and 44% correct procedures. CONCLUSIONS: The study shows that the two methodologies used, one to identify AE and the other to establish its causes and classification according to the EAPS, demonstrated usefulness and synergy for patient safety, when detecting AE, as well as determining their causes and evaluate compliance with the EAPS.