Fetal scalp nucleated red blood cell counts in pregnancies with meconium stained amniotic fluid

Abstract

CIES WITH MECONIUM STAINED AMNIOTIC FLUID ASAF FERBER, EBRAHIM SHAHIM, ALINA WEISSMANN-BRENNER, MICHAEL DIVON, Lenox Hill Hospital, OB/GYN, New York, NY OBJECTIVE: The clinical significance of meconium stained amniotic fluid (MEC) is still debated. Recent studies suggested that nucleated red blood cell (NRBC) counts are elevated in neonates with meconium aspiration syndrome. Thus, we sought to determine the correlation between intrapartum NRBC counts, pH values and MEC. STUDY DESIGN: Fetal scalp capillary blood specimens were prospectively collected in laboring patients who underwent scalp sampling. Specimens were evaluated for pH and NRBC counts. The presence and quality of meconium in the amniotic fluid were noted. Statistical analysis included Student’s t-test and simple regression. RESULTS: 78 term, singleton pregnancies formed the study population. The mean gestational age was 39.7 ± 1.2 ( ± S.D.) weeks. The mean birth weight was 3493 ± 451 grams. Themean scalp pHwas 7.26 ± 0.05 and themean NRBC per 100 WBC was 8.8 ± 8.3. Simple regression analysis revealed no significant correlation between fetal scalp pH and NRBC values (P = 0.94). 17 patients had MEC. Scalp pH values in patients with and without MEC were 7.25 ± 0.06 and 7.26 ± 0.05, respectively, P = 0.64. However, the NRBC counts in fetuses with MEC were significantly elevated (11.4 ± 10.6 vs. 7.4 ± 6.4, respectively, P = 0.031). Patients were further divided into clear fluid/thin MEC vs. moderate/thick MEC. There were no scalp pH differences between groups (7.24 ± 0.07 vs. 7.26 ± 0.05, respectively, P = 0.27). However, the NRBC counts in the moderate/thick MEC group were significantly different (14.0 ± 13.1 vs. 7.6 ± 6.2, respectively, P = 0.003). CONCLUSION: Previous studies have established an association between NRBC counts and perinatal outcome. Our results indicate that fetal NRBC counts are elevated in patients withmoderate/thick MEC. No such difference in pH values was noted. We speculate that scalp NRBC counts have the potential to either predict neonatal meconium aspiration syndrome or identify pregnancies that may benefit from immediate treatment.