Integrated care pathways (ICPs), a fine-grained form of medical guideline including the explicit recording of any deviation, or ‘variance’, could serve as a rich source of data for research. Not only do they incorporate a wealth of operational knowledge, but feeding the results of the analysis of variance into the development of a pathway could be an effective way of capturing evidence from practice. In our principal case study we propose a system for extracting data from care pathways with the aid of ontologies, and a method for inferring ICPs from other patient records, combining these with data collected for retrospective and prospective studies in preimplantation genetic diagnosis (PGD) for assisted reproduction.