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Dosing Rh immune globulin

KBassay still ahead despite tough rival

November 2003
William Check, PhD

In recent CAP HBF Surveys, a supplementary question was inserted by Chantal Harrison, MD, professor of pathology at University of Texas Health Science Center, San Antonio, and medical director of blood bank at University Hospitals. The question addresses an issue distinct from the method of measuring hemoglobin F: If one assumes an Rh-positive fetus within an Rh-negative mother, how many vials of Rh immune globulin would you give this patient?

For the last couple of Surveys, target values were very close to clinical decision points, 0.4 percent to 0.5 percent, says William Finn, MD, director of hematopathology at the University of Michigan Medical Center, who oversees the Survey. "Responses have generally been quite appropriate," he says. "Participants are generally recommending the right dose of Rh immune globulin. What we worry about is that with each Survey to date on which we have included this question, there have been a handful of participants who said they would not give any vials, which is never an appropriate answer when you have an Rh-negative mother with an Rh-positive baby."

Dr. Finn calls this "an educational issue."

"In the discussion of the most recent Survey," he says, "Dr. Harrison specifically stated that an Rh-negative mother who delivers an Rh-positive child should always receive at least one vial of Rh immune globulin after delivery." The second sample on the last mailing did have a slightly higher target value of fetal red cells, just under one percent. "I don’t think anyone recommended just one vial with that," Dr. Finn says.

-William Check, PhD