The Isabel project was inspired after my own daughter’s near fatal misdiagnosis in 1999. Last week I experienced my own misdiagnosis. Although far less serious, the episode is probably as instructive for the lessons it teaches. It showed me how easy it is to happen, how it’s often nothing to do with lack of time but just down to sloppy thinking. The discipline of doing a differential diagnosis (even for what seems a blindingly obvious, straightforward diagnosis) is crucial to avoid the sloppy thinking traps.