A primigravida at 36-weeks gestation, who is Rh negative, experienced abdominal trauma in a motor vehicle collision. Which assessment finding is most important for the nurse to report to the healthcare provider?

A. Fetal heart rate of 162 beats/minute is slightly above normal but may be a temporary finding and is not the most critical concern in this scenario. B. Mild contractions every 10 minutes should be monitored, but they are not as urgent as evidence of fetal blood in the maternal circulation. C. Trace protein in the urine is common in pregnancy and not the priority finding here. D. Positive fetal hemoglobin testing (Kleihauer-Betke test) indicates fetomaternal hemorrhage, which is a serious complication after abdominal trauma. In an Rh-negative mother, this finding requires prompt intervention with Rh immune globulin to prevent Rh sensitization and potential hemolytic disease of the newborn in future pregnancies.