Meconium aspiration syndrome in term neonates with normal acid-base status at delivery: Is it different?

Our aim was to compare the clinical characteristics of meconium aspiration syndrome in cases with pHor =7.20 and in those with pH7.20.Medical records of diagnostic codes from the International Classification of Diseases, Ninth Revision, were used to identify neonates with severe meconium aspiration syndrome who had been delivered at our institution from 1994 through 1998. Severe meconium aspiration syndrome was defined as a mechanical ventilator requirement of48 hours. Clinical data including neonatal outcomes of cases of meconium aspiration syndrome associated with umbilical pHor =7.20 at delivery were compared with data on outcomes of cases with pH7.20.During this 4-year study period, 4985 singleton term neonates were delivered through meconium-stained amniotic fluid. Forty-eight cases met all study criteria, and pH values at delivery were as follows: pHor =7.20, n = 29, and pH7.20, n = 19. There were no differences between groups in the incidence of clinical chorioamnionitis, in the presence of meconium below the vocal cords, or in birth weight. Neonates with meconium aspiration syndrome and umbilical pHor =7.20 at delivery developed seizures as often as those with pH7.20 (20.1% vs 21.1%; P = 1.0).Normal acid-base status at delivery is present in many cases of severe meconium aspiration syndrome, which suggests that either a preexisting injury or a nonhypoxic mechanism is often involved.