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 numbe...