Schema theory postulates that background knowledge facilitates and speeds up communication. According to the Common European Framework of Reference for Languages (CEFR), human communication is dependent on this knowledge, and language users are expected to have the appropriate level of world knowledge across a number of domains. PACTE group at Autonomous University of Barcelona is currently designing a similar framework for translators, and emphasises to the same degree the importance of background knowledge. While the practical need for background knowledge across specialised domains in language learning and in translation has been shown, the specific ways of capturing, organising and making it available for future users remains to be elucidated. The authors of this paper observed two professional interpreters prepare, produce an interpretation, and reflect on their work in the context of a conference in veterinary surgery. On at least four occasions the interpreters felt that their saturation levels were exceeded, and they self-reported the probable disruption in communication. During the follow-up interview they attributed the four problematic situations to their limited understanding of certain concepts that the speaker had chosen to refer to. We identified the exact pieces of information that the interpreters felt they lacked, and worked out a form of capturing, organising and transferring such information so that it be will a natural extension of the traditional self-preparation process. We propose two concepts: (1) The Index of Sophistication to predict the degree of professional complexity of a given text; and (2) A multilingual explanatory Databank, organised as a series of overlapping semantic networks that could help language users visualise and internalise the schemata in Medical domain. We think that this work has implications for interpreter/translator training, as well as for teaching English for Specific Purposes (Medical). By implementing the Index of Sophistication and the Databank, at least for some medical specialties, we could facilitate greater precision and validity of medical translation.