This book provides a descriptive analysis of the key issues regarding adverse events in hospitals. The term "adverse event" describes any harm to a patient as a result of medical care. An adverse event indicates that the care resulted in an undesirable clinical outcome and that the clinical outcome was not caused by an underlying disease. Research, policies, and action taken to reduce adverse events often focus on mistakes and systemic problems with care. However, adverse events do not always involve errors, negligence, or poor quality care and may not always be preventable.