RESUMO
A total of 3472 deliveries were studied over a year to evaluate (i) the importance of thin meconium stained liquor (MSL) in the causation of meconium aspiration syndrome (MAS), and (ii) the efficacy of intrapartum plus endotracheal suction at birth in the prevention of MAS due to thin meconium. Two hundred and ninety four (8.5%) of deliveries had meconium stained liquor of which thin MSL was present in 101. MAS occurred in 98 babies. Thin MSL was responsible for 19.4% of cases of MAS. Inspite of intrapartum suction, a high proportion (55-78%) of infants had meconium in the trachea, though thin meconium was found in the trachea significantly less often than thick meconium. Combined intrapartum and endotracheal suction reduced the incidence of MAS due to thin meconium from 26% to 16%. MAS due to thin meconium occurred in asphyxiated as well as vigorous babies inspite of combined suction. Thin meconium accounts for a significant proportion of deliveries with MSL and causes a considerable number of cases of MAS. To prevent meconium aspiration syndrome caused by thin meconium, all neonates born through thin MSL, whether they are asphyxiated or not should undergo intrapartum suction followed by immediate endotracheal suction at birth.