[Biochemical aspects of amniotic fluid aspiration].

The authors propose a simple, quick and reliable biochemical method for diagnosis of amniotic aspiration in the newborn infant. The optical density of the infant's first urine is determined at 420, 390 and 405 nm. A urinary meconial index (IMU) is computed from these values. A meconial amniotic inhalation must be suspected if this index is greater than one. The presence of coproporphyrins identified in urine of infants having inhaled meconial amniotic fluid seems to be at the origin of the spectral characteristics of pathological urines.