Interest of the Kleihauer in Patients With Decreased Active Fetal Movements

There are other arguments in favor of complicated fetomaternal hemorrhage: The fetal heart rate is often altered in severe fetal anemia, with sinusoidal rhythm being pathognomonic but uncommon. A slightly oscillating rhythm or variable decelerations are also found. On ultrasound, peak systolic middle cerebral artery velocity \> 1.5 MoM correlates with fetal anemia early before the appearance of hydrops. Some studies show that peak systolic middle cerebral artery velocity correlates better with neonatal hemoglobin than the Kleihauer test, for which no threshold has been found to predict an unfavorable outcome. Thus, even if the Kleihauer test is positive, the positive predictive value for fetal anemia is low. The detection of a small amount of fetomaternal hemorrhage by Kleihauer in the absence of evidence of anemia could even be deleterious, potentially leading to an excess of additional investigations and obstetrical interventions. The interest of systematically performing the Kleihauer test to search for fetomaternal hemorrhage is uncertain at this time because of the development and the undeniable contribution of ultrasound. However, in France, it is still carried out in most maternity wards in the absence of recommendations for any decrease in active fetal movements. Only one article has looked specifically at fetomaternal hemorrhage in a group of patients consulting for a decrease in active fetal movements, calling into question its interest.