Use of Fetal Hemoglobin Quantitation for Rh-Positive Pregnant Females: A National Survey and Review of the Literature.

CONTEXT.­: The Kleihauer-Betke (KB) test is validated for estimating the dose of Rh immune globulin needed for Rh-negative pregnant females. However, some clinicians are also ordering the test for Rh-positive women. The degree to which this practice occurs is unknown. OBJECTIVE.­: To evaluate the number of laboratories that perform the KB test on Rh-positive pregnant women, and to establish current ordering practices for this indication. DESIGN.­: We added 9 supplemental questions regarding KB test use for fetomaternal hemorrhage to the 2016 College of American Pathologists proficiency test survey. We also reviewed the available literature regarding the diagnostic utility of the KB test for Rh-positive women. RESULTS.­: A total of 1578 surveys were evaluated and revealed that 52% (824) of respondents perform these tests for Rh-positive women, and more than 50% (440 of 819; 53.7%) of these laboratories report that the results for Rh-positive women are treated as important or very important. CONCLUSIONS.­: The KB test is commonly used for Rh-positive women, and the information obtained from the test is considered as urgent and important. However, the available literature in support of this practice is still nonconclusive.