Clinical use of the Kleihauer-Betke test

Results of all Kleihauer-Betke (KB) tests performed in 1988, at a center with 4,201 deliveries, were reviewed. Two hundred and twenty-seven tests were performed on maternal specimens from 205 patients. Eighteen (8.8%) of the 205 patients had positive test results. Medical records were available for 147 (71.7%) of the patients, including 17 of the 18 patients with a positive result. Indications for testing were: vaginal bleeding (33%), maternal trauma (31%), unexplained fetal death (5%), Rh incompatibility (3%), fetal distress (3%), and miscellaneous (24%). Most of the tests were performed antepartum. In only one case, and without clear benefit, did the KB test prompt a clinical intervention. At least two of the 18 patients with positive test results had probable false positive results due to maternal hemoglobin F. Such false positive KB test results may be misleading. Further evaluation of the role of the KB test in obstetrical management is needed.