Original Articles
Neonatal Nucleated Red Blood Cell and Lymphocyte Counts in Fetal Brain Injury 1

https://doi.org/10.1016/S0029-7844(98)00039-8Get rights and content

Abstract

Objective: To determine whether neonatal lymphocyte or nucleated red blood cell (RBC) counts can be used to date fetal neurologic injury.

Methods: Singleton, term infants with hypoxic-ischemic encephalopathy, permanent neurologic impairment, and sufficient laboratory data were divided into two groups: infants with preadmission injury, manifested by a nonreactive fetal heart rate (FHR) pattern from admission until delivery; and infants with acute injury, manifested by a normal FHR pattern followed by a sudden prolonged FHR deceleration. Lymphocyte and nucleated RBC values were compared with published high normal counts for normal neonates: 8000 lymphocytes/mm3 and 2000 nucleated RBCs/mm3.

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 lymphocyte count tended to be higher in the preadmission-injury group than in the acute-injury group. In comparison, nucleated RBC values were not correlated as strongly with neonatal hours of life; nucleated RBC counts tended to be higher and persist longer among neonates with preadmission injury than among those with acute injury.

Conclusion: Compared with normal levels, both lymphocyte and nucleated RBC counts were elevated among neonates with fetal asphyxial injury. Both counts appear to be more elevated and to remain elevated longer in newborns with preadmission injury than in infants with acute injury. However, the rapid normalization of lymphocyte counts in these injured neonates limits the clinical usefulness of these counts after the first several hours of life.

Section snippets

Materials and Methods

Singleton, term infants (37 weeks’ gestation or greater) with hypoxic-ischemic encephalopathy in the neonatal period and resulting permanent neurologic impairment were identified in a national registry for brain-injured infants established in 1991. All neurologic injuries were confirmed by a pediatric neurologist. The details of the population and the study methods have been described previously.1, 2Subjects were excluded if they had conditions known to be associated with elevated nucleated RBC

Results

Of the 292 patients in the registry, 101 met entry criteria. Reasons for exclusions and the composition of the final study population are listed in Table 1. Sixty-six of these patients (65%) were from the preadmission-injury group and 35 (35%) were from the acute-injury group. Maternal demographic features with respect to age, gravidity, parity, abortions, gestational age at the time of delivery, antenatal complications, and prenatal care were similar for both groups. The types of events

Discussion

It appeared that lymphocyte counts were more likely to be elevated among neonates with fetal asphyxial injury than among normal neonates. This elevation was transient and the counts decreased rapidly from the time of birth and normalized in less than 24 hours. Only 62% of the brain-injured infants had lymphocyte counts greater than 8000 cells/mm3 in the first 6 hours of life. Therefore, lymphocyte count cannot be considered a categoric indicator of brain injury. A large proportion (67%) of the

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1

This project was sponsored in part by the Childbirth Injury Prevention Foundation.

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