"In the preface to the third edition, Dr. Paul Mintz wrote, "It is tempting to wonder what will (and will not) be included in the fourth edition." No need to wonder any longer. The editorial team for this edition has reorganized and refreshed the content to reflect the many changes in the transfusion medicine landscape in the intervening years. Chapter authors have emphasized evidence-based recommendations wherever possible to aid both primary and consultative clinicians. The 22 chapters are grouped in three sections: Blood Products and Derivatives, Transfusion Medicine Practice, and Management Aspects of Transfusion Practice. The first section addresses (among other topics) pathogen reduction, unit age influence on patient outcome, and expanding modifications of components, as well as clinical use of components and derivatives. Chapters in the central section focus on sometimes-challenging areas of transfusion medicine such as use of extracorporeal devices; support for pregnant patients, neonates, and children; care of those who refuse consent; management of, and testing for, hemostasis-among many others. The final section brings readers up to date on management aspects, including hemovigilance, medico-legal issues, quality, regulations, and initiatives and metrics for optimal blood utilization"--