Alloimmunization From Transfusions Clinical Presentation

Updated: Sep 08, 2017
  • Author: Douglas Blackall, MD, MPH; Chief Editor: Michael A Kaliner, MD  more...
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Delayed hemolytic transfusion reactions

Hemolysis is usually extravascular, but in rare cases a component of intravascular hemolysis is present.

Most cases manifest during the second week after transfusion, but the reaction can occur from 24 hours to 3 months after the transfusion.

Many patients are asymptomatic, and the condition is oftentimes detected only by laboratory testing. [7]

In some patients, fever and/or chills (50%), jaundice (10%), pain (3%), and dyspnea (1%) can occur.

Rarely, cases may be complicated by renal failure (6%) or disseminated intravascular coagulation (1%).

In patients with sickle cell disease, a DHTR can precipitate a sickling crisis. [8]

Refractoriness to platelet transfusions

Frequently, patients with refractoriness to platelet transfusion are asymptomatic and diagnosed by laboratory methods; however, failure to achieve hemostatic levels of platelets may preclude these patients from important procedures, including bone marrow transplantation. Alloimmunization should be avoided in candidates for bone marrow transplantation.

Preexisting bleeding resulting from thrombocytopenia may persist after transfusion of an appropriate therapeutic dose of platelets. [9] Rarely, spontaneous bleeding may occur after prophylactic transfusion of platelets.



Alloimmunization to blood antigens occurs after the following:

  • Transfusion

  • Pregnancy

  • Transplantation

  • Sharing intravenous needles (rare)