Objectives Medical teaching teams (MTTs) must balance teaching and patient care in the face of three challenges: shifting team membership, varying levels of learners and patient complexity. To support care, MTTs rely on a combination of recurrent oral and written communication practices (genres), such as admission, progress and discharge notes. The purpose of this study was to explore how these genres influence the team's ability to collectively care for patients. MethodsThis was a multiple case study with data collected through observations and audio-recordings of 19 patient cases focusing on admission review discussions and chart documents throughout the hospitalisation. Participants included 14 medical students, 32 residents and 10 attending physicians rotating through one of three internal medicine MTTs. We used constant comparative analysis to identify recurrent patterns across the multiple cases, which were further elaborated in a return-of-findings focus group. ResultsThe MTT genre system facilitated the care of patients through progressive collaborative refinement' (PCR): MTTs use case and data reviews to collaboratively and progressively refine their understanding of the patient's problems and develop strategies for addressing them. Progressive collaborative refinement was apparent through modifications made in the documentation. Although modifications were a necessary component, they were not sufficient: some modifications were made without refinement. We characterised incidents of failed modification as fragmentation'. Three types were observed: conceptualisation, documentation and continuity of care providers. In most cases, all three were present and interacted to impede PCR. ConclusionsProgressive collaborative refinement was used by MTTs to provide the optimal care to patients. Progressive collaborative refinement was impeded by a lack of continuity of care providers and gaps between communication genres that fragmented conceptualisation and documentation. Progressive collaborative refinement can be understood as both an overarching process and a shared but unstated ideal. Through defining and describing PCR, the present findings can be used to improve communication and teaching. Discuss ideas arising from the article at '