Newborn Drug Screening: Differential Outcome Using Meconium Versus Umbilical Cord Tissue

Background Identification of newborns exposed to illicit drugs during pregnancy is important to assess families with substance abuse disorders requiring a close follow-up of the infant by both medical and social services. Drug screening and confirmation in newborns has been traditionally performed on meconium. In recent years, umbilical cord (UC) tissue has gained popularity as an alternative specimen. Here, we present two cases of paired meconium and UC drug testing leading to different outcomes. The objective of this report is to highlight the inconsistencies that may occur with paired testing, and how these results may be interpreted. Methods We report two cases of newborn drug screening of premature infants born to mothers with a history of drug abuse. The drug testing was performed on paired meconium, UC tissue and/or urine samples. UC tissue testing was referred to NMS laboratories (Horsham, PA) using HPLC-MS/MS followed by confirmation with the same method. Meconium samples were analyzed by LabCorp laboratories (Louisville, KY) using immunoassay followed by confirmation by HPLC-MS/MS. Urine drug screening was performed on both maternal and newborn samples at University of Louisville Hospital (ULH) using an immunoassay-based method. Confirmation of urine drug screening was confirmed with HPLC-MS/MS send-out to LabCorp. Each specimen was tested for amphetamine, methamphetamine, opiates, cocaine, cannabinoids and phencyclidine. Results Case I: An early term infant was born at 38 weeks and 3 days to a 35-year-old mother who has a history of drug abuse of amphetamines and opiates. Initially, the urine drug screens from both the mother and the baby were positive for amphetamine and/or methamphetamine. Meconium drug screening indicated the presence of amphetamine, methamphetamine, morphine, codeine, benzoylecgonine and m-OH-benzoylecgonine. In the UC, codeine was not detected, and fentanyl and norfentanyl gave positive results. Case II A preterm infant was born at approximately 36 weeks to a 33-year-old mother who had a history of drug abuse, stillbirth, and was diagnosed with hepatitis C. The mother had no prenatal care or ultrasounds for this pregnancy. Maternal urine drug screening was positive for amphetamine, methamphetamine and buprenorphine; the newborn’s urine sample was not available at that time. No confirmation was performed for UDS. LC-MS/MS toxicology testing on meconium revealed the presence of amphetamine, methamphetamine, buprenorphine and its metabolite norbuprenorphine. UC did not detect any buprenorphine or norbuprenorphine. Conclusion The two cases have revealed different sensitivities for drug detection in meconium and UC tissue. Meconium, to a significant extent, provides higher sensitivity, and is likely to remain the specimen of choice when sensitivity is of greatest importance. These results can help clinicians, laboratorians, and epidemiologists to (1) select the most appropriate test to confirm a suspected drug exposure and (2) interpret discordant results when testing is performed in multiple matrices.