Do placental sections accurately reflect umbilical cord nucleated red blood cell and white blood cell differential counts?

Elevated levels of umbilical cord nucleated red blood cells (nRBCs) have been used to assess in utero hypoxia. Although the umbilical nRBC value has been the 'gold standard', umbilical blood may not be obtained at delivery. We determined if the levels of nRBCs and white blood cell (WBC) counts in fixed placental sections might serve as a proxy for cord blood values.Umbilical blood and placenta were collected from 25 deliveries at Harbor-UCLA Medical Center. Umbilical blood and placental sections were analyzed for nRBCs (per 100 WBC) and WBC differential, and compared with the t-test or the Mann-Whitney rank sum test.nRBC counts were equivalent in umbilical cord and placental sections (5 vs. 4/100 WBC). Umbilical lymphocyte and polymorphonuclear leukocyte (PMN) counts were normally distributed, averaging 35 +/- 9 and 56 +/- 2/100 WBC, respectively. Placental lymphocyte (33 +/- 2/100 WBC) and PMN (60 +/- 2/100 WBC) counts were equivalent to cord blood values.WBC differentials and nRBC counts are equivalent in umbilical cord blood and processed placental pathology sections. For infants in whom cord blood cell counts are desired though umbilical cord samples are unavailable, fixed placental sections may serve as a proxy.