The absence of a fetal response to vibroacoustic stimulation (VAS) performed during labor may be an indicator of fetal acidemia. A lack of fetal heart rate (FHR) acceleration following VAS has been correlated with fetal scalp blood pH < 7.20. A measurement of pH alone cannot distinguish respiratory from metabolic acidosis. This study correlates the FHR response to VAS during labor with fetal scalp blood pH and base deficit levels. The mean pH and base deficit levels of patients not demonstrating FHR response were 7.24 and 5.90 mEq/L, respectively. A lack of FHR response after VAS was moderately sensitive to detect pH < 7.20 but more sensitive to detect pH < 7.10. A lack of FHR acceleration was moderately sensitive to detect base deficit > 7 mEq/L but was more sensitive to detect levels >10 mEq/L. All patients with pH < 7.20 and demonstrating FHR response after VAS had base deficit < 10 mEq/L. Forty-four percent of patients with pH < 7.20 and no FHR response after VAS had base deficit > 10 mEq/L. This study suggests that VAS during labor can predict fetal acidemia and differentiate between respiratory and metabolic acidosis.
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.
1The New York Hospital–Cornell Medical Center, Cornell University Medical College, New York, New York 2Washington University School of Medicine, St. Louis, Missouri
