STUDY OBJECTIVE: Our objective was to develop a clinical scale (the VENSCORE) to predict pre-operative peripheral intravenous cannula (PIVC) insertion failure at the first attempt in adults. DESIGN: This was a prospective multicenter cohort study that included internal validation with bootstrapping. SETTING: The operating rooms of 14 hospitals in southern France from June 2016 to June 2018. PATIENTS: Consecutive adult patients aged 18 years or older were recruited upon arrival to the operating room, regardless of American Society of Anaesthesiology (ASA) physical status. INTERVENTIONS: PIVC insertion on arrival to the OR. MEASUREMENTS: PIVC insertion failure at the first attempt was the outcome of interest. Data collected included the number of PIVC insertion attempts and potential predictors of the risk of failure (including pre-operative patient characteristics and data relative to the procedure). Uni- and multivariable logistic analyses were performed. Based on these results, the VENSCORE scale was developed to predict the risk of failure of the first PIVC insertion. MAIN RESULTS: In total, 3394 patients were included, and 27 were excluded because of protocol violations. The PIVC insertion failure rate at the first attempt was 20.3%. Based on multivariable analysis, a history of difficult PIVC insertions, high-risk surgery, poor vein visibility, and moderate to poor vein palpability were identified as risk factors for insertion failure at the first attempt. The area under the curve of the predictive model was 0.82 (95% confidence interval: 0.80-0.84). A VENSCORE value of 0 points was associated with a failure rate of 7%, versus 97% for a score of 6. CONCLUSIONS: The four-item VENSCORE scale could be useful for prospectively identifying adults at risk of first PIVC insertion attempt failure.< Réduire