Effectiveness of the RhIg dose calculator.
To evaluate the effectiveness of the RhIg Dose Calculator, supplemental questions were included in the HBF-B 2009 Survey, asking participants to submit the dose (number of vials) of RhIg that their laboratory would recommend for a postpartum Rh(D)-negative woman whose quantitative assay result for fetal RBCs was "1% = 50 mL whole blood." (4) Of 1681 participants responding, only 1263 (75.1%) submitted the correct answer (3 vials), according to the method of the AABB Technical Manual. (4) Of 418 (24.9%) participants submitting an erroneous or "other" response, 187 (44.7%) reported that they used the method of the Technical Manual. Of 1122 participants who calculated the dose of RhIg using the method of the Technical Manual, 187 (16.7%) submitted an erroneous or other" response. In contrast, of the 129 participants using the RhIg Dose Calculator, only 2 (1.6%) submitted erroneous results. Laboratories are encouraged to use the RhIg Dose Calculator, if only to verify their standard method for calculating the postpartum dose of RhIg. The results of this survey demonstrate the potential effectiveness of the RhIg Dose Calculator for preventing inaccurate calculations for the recommended postpartum dose of RhIg. Although laboratories are encouraged to use the RhIg Dose Calculator as a method for ensuring accurate calculations according to the method of the AABB Technical Manual, readers should be aware that other formulae are available and may be used to calculate the dose of RhIg. (1) The RhIg Dose Calculator is provided as a service to laboratories. Its use is voluntary and does not, necessarily, ensure a successful medical outcome.
(1.) Ramsey G; for the College of American Pathologists Transfusion Medicine Resource Committee. Inaccurate doses of Rh immune globulin after Rh-incompatible fetomaternal hemorrhage: survey of laboratory practice. Arch Path Lab Med. 2009;133(3):465-469.
(2.) Paxton A. Bringing new rigor to RhIg calculations. CAP Today. 2008;22(5):1.
(3.) Roback JD, Combs MR, Grossman BJ, Hillyer CD, eds. Technical Manual. 16th ed. Bethesda, MD: AABB; 2008:631-632.
(4.) Sandler SG. 2009 CAP surveys: HBF-B fetal RBC detection: Interlaboratory Comparison Program participant summary. Northfield, IL: College of American Pathologists; 2009.
The author has no relevant financial interest in the products or companies described in this article.
S. Gerald Sandler, MD
Department of Laboratory Medicine
Georgetown University Hospital
Washington, DC 20007
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|Title Annotation:||Letters to the Editor|
|Author:||Sandler, S. Gerald|
|Publication:||Archives of Pathology & Laboratory Medicine|
|Article Type:||Letter to the editor|
|Date:||Jul 1, 2010|
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