NEONATAL NUCLEATED RED-BLOOD-CELL AND LYMPHOCYTE COUNTS IN FETAL BRAIN INJURY

Objective: To determine whether neonatal lymphocyte or nucleated red b lood cell (RBC) counts can be used to date fetal neurologic injury. Me thods: Singleton, term;infants with hypoxic-ischemic encephalopathy, p ermanent neurologic impairment, and sufficient laboratory data were di vided into two groups: infants with preadmission injury, manifested by a nonreactive fetal heart rate (FHR) pattern from admission until del ivery; and infants with acute injury, manifested by a normal FHR patte rn followed by a sudden prolonged FHR deceleration. Lymphocyte and nuc leated RBC values were compared with published high normal counts for normal neonates: 8000 lymphocytes/mm(3) and 2000 nucleated RBCs/mm(3). Results: The study population consisted of 101 neonates. In the first hours of life, lymphocyte counts were elevated among injured newborns , and then the counts rapidly normalized. Brain-injured neonates were 25 times more likely to have a lymphocyte count greater than 8000 than were normal neonates (54 [62%] of 87 versus 6 [7%] of 84; odds ratio 25.5; 95% confidence interval 8.8, 80.1; P < .001). The mean lymphocyt e count tended to be higher in the preadmission-injury group than in t he acute-injury group. In comparison, nucleated RBC values were not co rrelated as strongly with neonatal hours of life; nucleated RBC counts tended to be higher and persist longer among neonates with preadmissi on injury than among those with acute injury. Conclusion: Compared wit h normal levels, both lymphocyte and nucleated RBC counts were elevate d among neonates with fetal asphyxial injury. Both counts appear to be more elevated and to remain elevated longer in newborns with preadmis sion injury than in infants with acute injury. However, the rapid norm alization of lymphocyte counts in these injured neonates limits the cl inical usefulness of these counts after the first several hours of lif e. (C) 1998 by The American College of Obstetricians and Gynecologists .