A delayed hemolytic transfusion reaction (DHTR) is a type of transfusion reaction. According to the Centers for Disease Control's (CDC) National Healthcare Safety Network's (NHSN) Hemovigilance Module, it is defined as: A delayed hemolytic transfusion reaction (DHTR) is a type of transfusion reaction. According to the Centers for Disease Control's (CDC) National Healthcare Safety Network's (NHSN) Hemovigilance Module, it is defined as: