433 - Concordance of test results between maternal drug screen and urine versus cord tissue drug screens in newborns

Publication Number: 433.4475

Karthikeyan Meganathan, University of Cincinnati College of Medicine, Cincinnati, OH, United States; Henry Akinbi, University of Cincinnati College of Medicine, Cincinnati, OH, United States

Background: Accuracy of maternal and newborn drug screens used to assess fetal drug exposure and to determine the risk for Neonatal Opioid Withdrawal Syndrome depends on matrix and testing platforms.

Objective: Of the several biological matrices, with differing sensitivities and detection windows, urine and cord tissues are commonly used in practice. The goal of this study is to compare concordance of toxicological findings from infants at risk for in utero drug exposure that had urine, cord tissue or both matrices with maternal urine drug screen (UDS) result.

Design/Methods: This is a retrospective review of the correlation between drug screens test results for psychotropic drugs in parturient mothers and of neonatal urine versus umbilical tissue testing at a single site with universal drug testing in pregnant women in the Labor and Delivery Unit. Positive maternal immunoassay results are reflexed to confirmatory testing by liquid chromatography tandem mass spectrometry (LC-MS/MS). Infants delivered to mothers with a positive drug screen are evaluated for in utero drug exposure by testing urine, cord tissue, or both matrices using LC-MS/MS. Predictive values and agreement between mothers’ test results and neonates’ urine/cord tissue results were analyzed using Cohen’s kappa statistics.

Results: Of a total 757 mother-baby dyads with maternal test confirmations, 359 neonatal urine tests and 547 cord tissue tests were paired with maternal urine drug screens. Of these, 216 neonates had both urine and cord tissue tests. Occurrences of barbiturates, benzodiazepines, cannabinoids, opioids, stimulants and TCA were analyzed. Agreement of newborn urine drug screen and cord tissue with mother’s test result and predictive values are summarized in Table. Overall, agreement with mothers' test results was higher for neonatal urine test. Neonate urine test exhibited lower sensitivity to benzodiazepines, cannabinoids and TCA and lower specificity to opioids. Neonate cord test exhibited lower sensitivity to benzodiazepines, opioids and TCA.

Conclusion(s): Generally, there was high agreement between neonatal and maternal toxicology test results. Neonatal urine and umbilical tissues exhibited discordance with maternal testing for different drug classes. Overall, neonatal urine, analyzed with high sensitivity LC-MS/MS, was less discordant with maternal UDS than cord tissue. Coupled with quicker turn-around time, neonatal urine testing offers better clinical utility than cord tissue. Our data should prompt re-evaluation of current cut-off levels as well as investigations into alternative biological matrices.

Performance of Urine Versus Cord Tissue Drug Screen
Table_PDF.pdf