Meconium analysis for cocaine: a validation study and comparison with paired urine analysis

We established the validity of a drug-screening method to detect the presence of cocaine or benzoylecgonine or both in meconium and then undertook an analysis of results from urine and meconium specimens obtained concurrently from neonates within 3 days of birth. Meconium specimens from 82 consecutive newborns were analyzed using fluorescence polarization immunoassay (FPIA), Kinetic Interaction of Microparticles in Solution (KIMS), and gas chromatography-mass spectrometry (GC-MS). Each meconium specimen was analyzed by all three methods. Fifty-four paired urine and meconium specimens were obtained over a 13-month period from a neonatal intensive care unit. Urine drug testing was performed by immunoassay (enzyme multiplied immunoassay [EMIT] technique), whereas meconium specimens utilized FPIA with GC-MS confirmation on all but one specimen (due to insufficient quantity). Ten true positives were found by GC-MS, 10 positives were found by FPIA, and 70 positives were found by KIMS. Of the 54 paired samples, 39 samples tested negative for cocaine in both urine and meconium; four specimens were positive by both routes; 10 specimens were negative in urine but positive in the meconium; and one specimen tested positive in urine but negative in the meconium. Thus, 9.3% of the urine specimens tested positive, and 25.9% of meconium samples tested positive (p = .011; McNemar's Test). We conclude that screening meconium specimens by FPIA followed by GC-MS confirmation of screened positives yields highly accurate determinations of the presence of cocaine or benzoylecgonine or both in meconium and that testing of meconium for cocaine and its metabolites is more sensitive than testing of urine.