Administering anti-D immunoglobulin (Ig) within 10 days, although ideally within 72 hours, to Rhesus (Rh)-negative women who have given birth to an Rh-positive baby may provide some protection, according to findings from a letter to the editor published recently in the Air Medical Journal.
Anti-D Ig is given to Rh-negative pregnant patients to prevent the development of hemolytic disease of the fetus and newborn (HDFN). The administration of anti-D Ig is carried out for the purposes of preventing the production of antibodies that are directed against D-positive cells, because RhD-alloimmunization can lead to HDFN in a future pregnancy.
The authors of the current editorial sought to evaluate the recent article by McCartin and colleagues, also published in Air Medical Journal, which assessed management considerations regarding air medical transport programs involving the transportation of RhD-negative red blood cell (RBC)–containing blood products to females of childbearing potential.
In all situations in which medical intervention is justified, a well-defined evaluation is required, in which the advantages and disadvantages of a particular procedure or treatment are considered. In certain instances, “the reason for the RhD-positive blood transfusion, especially several units, may already imply that the severity of the patient’s condition will not allow an invasive procedure [such as RBC] exchange and the potential risks of hemolysis because of high-dose anti-D Ig.” In fact, in order for alloimmunization to be recognized as posing a concern, a patient must first survive the current trauma that is being experienced.
Read more about HDFN symptoms of and risks
In other words, in situations in which the development of HDFN is a distinct possibility, a patient must be alive to be able to discuss the probable development of and consequences associated with HDFN.
It is also important to recognize that the only effect associated with D immunization in females beyond childbearing potential, as well as males, is the requirement of RhD-negative blood components in any future blood transfusions they may receive if they develop alloanti-D, in which anti-D alloantibodies are generated.
Additional data needed to confirm findings
It is recommended that follow-up via use of an antibody screen to detect anti-D development takes place six months following an RhD-positive RBC transfusion and the subsequent intervention with high-dose anti-D Ig.
“Distinguishing anti-D Ig from alloanti-D may yet be a challenge and can to some degree be overcome by antibody titration,” the authors stated.
Of note, if an anti-D titer is higher than 1:16 at six months following such a transfusion, the detected antibody thus suggests alloimmunization. A negative antibody screen after six months, however, does not imply that alloimmunization has not taken place.
In the analysis by McCartin and coworkers, testing and analysis, which are considered a key component of mathematical modeling, are both missing. Although McCartin and associates conduct sensitivity analyses, specificity, precision and negative performance predictors, and accuracy analyses are missing from their review.
The authors of the editorial noted that “it would be advisable to assess the model [presented by McCartin and colleagues] in more detail.” Even though values, distributions, and data sources are detailed in the article, “there is no discussion about the selection of variables or other potential models.”
