Methods: We have formally defined the blood transfusion process, including identifying prerequisites that must be satisfied for carrying out each step in the process and ways that the execution of each step could fail.  We are also analyzing the formal process definition to determine whether the process satisfies its safety requirements.  We are using a tool originally developed for use in checking computer programs for identifying and clarifying ambiguities and omissions in the conventional statements of the safety conditions that the process is intended to enforce. 

 Results:  Potential error-prone situations have been identified that had not previously been considered.  The majority of these error prone situations are related to patient identification and specimen labeling.  Other error-prone situations are those related to provider communication issues related to a suspected transfusion reaction.   We have also identified a number of exceptional/non-standard conditions, such as the comatose patient with a missing armband who requires a blood transfusion.

 Conclusion: Formal process definition allows for the precise representation of the blood transfusion process in both standard and exceptional situations. We are currently in the early stages of using process formalization to improve the safety of blood transfusion. To date, we have focused on eliciting and adequately representing the blood transfusion process.  In the future, we will be conducting an evaluation of this formal definition in a simulated clinical setting.