This paper describes an innovative methodological approach developed within the SAFROS European project (Patient Safety in Robotic Surgery, FP7) that allows to identify a set of metrics for the evaluation of patient safety during the pre- and intra-operative phase of robotic interventions. This methodology enlarges the focus of the evaluation: safety is assessed not only through the analysis of features and limitations of the technological solutions involved in the execution of target surgical interventions (product safety) but also in terms of the effects of their interaction within the surgical scenario (process safety). Moreover potentialities and obstacles emerging from the introduction of such technologies into the operating room and the hospital as systems (organizational safety) are evaluated. The proposed method has been applied to the analysis of one gold standard and two benchmark procedures. The output of the analysis is a complex set of key metrics addressing safety at the above described levels. This paper reports the most relevant and interesting subset of the obtained results. The extendibility of the method to the analysis of other interventions will be verified with suitable experiments in the next future.