Delayed Hemolytic Transfusion Reactions

Description

Delayed Hemolytic Transfusion Reactions (DHTR) involve the destruction of transfused red blood cells (RBCs) after an interval of time, usually 3 to 21 days following transfusion, with most occurring about 7 days post-transfusion.

DHTR occur when weak alloantibodies that are undetected in pretransfusion antibody screening tests increase in strength following a secondary (anamnestic) antibody response to transfused donor red cells possessing the corresponding antigen. Such antibodies occur in persons originally sensitized by exposure to RBCs through previous transfusions and/or pregnancies.

Antibodies of several blood group systems may cause DHTR, with antibodies in the Rh (anti-c, -E), Kidd (anti-Jka), Kell (anti-K), and Duffy (anti-Fya) systems most often implicated.

NOTE: Historically, many reactions classed as DHTR did not involve red cell destruction but rather serologic criteria such as antibody production post-transfusion and development of a positive Direct Antiglobulin Test (DAT). The latter events have been termed Delayed Serologic Transfusion Reactions (DSTR).

Incidence

The reported incidences of DHTR vary with types of patients, degree of surveillance, length of time following the transfusion over which data is collected, criteria used to define the reaction, and sensitivity of antibody detection methods.

In studies done since the 1980s, the incidence of DHTR includes rates ranging from 1:5405 to 1:9094 per RBC unit transfused.