Correlation of Umbilical Cord Arterial pH and Standard Base Excess in Term Neonates With Neurologic Examination at Discharge: A Cohort Study

Abstract

Background

Umbilical cord arterial pH less than 7.0 and base excess ≥12 mmol/L are associated with adverse short and long-term neurologic outcomes. Hammersmith Neonatal Neurological Examination (HNNE) is used to predict long-term neurologic outcomes; its validity has been established at discharge.

Methods

This study was done to find the correlation between umbilical cord arterial pH and standard base excess with HNNE score, subsection scores at discharge. Fifty-five term neonates with perinatal asphyxia defined as umbilical cord arterial pH <7.0 and/or base excess ≥12 mmol/L and 55 healthy neonates with umbilical cord arterial pH >7.2 were examined by HNNE scores at discharge and the correlation between umbilical cord arterial pH and standard base excess with HNNE score was calculated.

Results

Among 55 neonates with perinatal asphyxia, all developed hypoxic-ischemic encephalopathy (HIE) with 21 (38%) at stage I, 26 (47%) stage II, and 8 (15%) stage III. The mean HNNE scores of neonates with perinatal asphyxia were lower than healthy neonates (20.2 ± 3.13 vs 31.65 ± 1.92; P < .0001). The difference was significant in subsection scores too. On plotting HNNE scores and umbilical cord arterial pH on a linear scale, Pearson correlation coefficient showed good correlation (r = 0.797, 95% CI 0.716-0.857; R² 0.636; P < .001) between the two. On plotting HNNE scores and standard base excess on a linear scale, Pearson correlation coefficient showed negative poor correlation (r = –0.349, with 95% CI 0.17 to 0.50, P < .001).

Conclusion

HNNE scores at discharge were significantly lower among term neonates with perinatal asphyxia than in healthy neonates. There was good correlation between umbilical cord arterial pH and HNNE scores at discharge. Standard base excess was not associated with HNNE scores.