Meconium aspiration syndrome

Case history #1

A term, male newborn weighing 2968 g (6 lb, 9 oz) has been delivered at a tertiary hospital at 39 weeks' gestation by emergency caesarean section because of fetal tachycardia and meconium-stained amniotic fluid (MSAF). The mother is a 17-year-old primigravida who had group B beta-streptococcal-positive culture at 35 weeks' gestation. At delivery, the infant is limp and blue with poor respiratory effort. He has an Apgar score of 4 at 1 minute. The infant's skin and umbilical cord are stained green, and he continues to demonstrate tachypnoea, with a respiratory rate of 70/minute, mild retractions, and grunting.

Case history #2

A female infant is delivered post-term (at 42 weeks, 6 days) by emergency caesarean section because of fetal distress and thick MSAF. The birth weight is 3000 g (6 lb 10 oz). She presents with moderate retractions and grunting with an Apgar score of 3 at 1 minute.

Other presentations

Atypical presentations include an initial normal presentation, with deterioration later if meconium-stained amniotic fluid and fetal distress are not recognised at birth. In some term births in which the history of meconium aspiration is not obvious, cyanotic heart disease may be incorrectly diagnosed.

Although MAS is common in term and post-mature babies, it can also be seen in preterm infants, though less commonly. In preterm infants, MAS may be misdiagnosed as respiratory distress syndrome resulting from surfactant deficiency.