1 Assistant Professor of Clinical Medicine, Division of General Internal Medicine, Section of Hospital Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. E-mail: Nikhil.Mull@uphs.upenn.edu.
2 Assistant Director, Center for Evidence-based Practice, University of Pennsylvania Health System, Philadelphia, PA, USA.
3 Director, Internal Medicine Residency Program, Allegheny Health Network, Pittsburgh, PA, USA.
4 Assistant Professor of Medicine, Temple University, Pittsburgh, PA, USA.
5 Associate Professor of Medicine, Division of General Internal Medicine, Section of Hospital Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Errors in diagnosis can arise from the clinician's cognitive biases as well as from problems in the healthcare system. Here the authors review a case with a bad outcome to analyze what went wrong and why.