Drug Detection Panel Testing, Meconium and Umbilical Cord Tissue

Testing biological specimens such as meconium and umbilical cord tissue to detect prenatal drug exposure is preferred to maternal self-reporting because drug use is generally underreported by pregnant individuals.  For example, in a recent study, 2.6% of expectant individuals reported marijuana use to their healthcare providers; however, marijuana metabolite (THC-COOH) was detected in 22.4% using an umbilical cord assay. 

Testing may be indicated for neonates born with unexplained neurological complications, growth restriction, or evidence of drug withdrawal symptoms (eg, neonatal abstinence syndrome [NAS]). Testing may also be indicated if the pregnant individual has a history of high-risk behaviors (eg, drug use/misuse/abuse), has had little or no prenatal care, or has experienced unexplained placental abruption or premature labor. 

Umbilical cord tissue testing may be preferable to meconium testing in certain contexts due to the ease and speed of collection and comparable window of detection.  Collecting both specimen types may increase detection of drug exposure. For a detailed discussion of newborn drug testing and the use of these specimens, refer to the Newborn Drug Screening - Meconium and Umbilical Cord Tissue topic.

Disease Overview

Timely detection of in utero drug exposure supports the identification and clinical management of affected neonates.   The actual time window for detecting exposure is drug dependent, but results are thought to represent approximately the last trimester of a full-term pregnancy. 

Detection of drugs is subject to the following factors :

• Extent of maternal drug use
• Specific drug(s) used
• Deposition of drug analytes in meconium or umbilical cord tissue, which varies based on the chemistry of the drug analyte and the unique characteristics of each specimen
• Performance characteristics of test method

Test Interpretation

Sensitivity/Specificity

• Clinical sensitivity: Detection of most compounds and metabolites is consistent between meconium and umbilical cord tissue testing, but results may not correlate with those of maternal urine testing or maternal self-report. In general, concentrations of drug analytes are lower in umbilical cord tissue than in meconium.
• Specificity: high; mass spectrometric methodology and inclusion of multiple drug analytes/metabolites minimizes false positives and the need for confirmatory testing.
• Analytical sensitivity: dependent on method details and cutoff concentration for the analyte(s) of interest; cutoff concentrations have been selected to maximize agreement between meconium and umbilical cord tissue while assuring accuracy and precision requirements.

Results

Limitations

• The pattern and frequency of drug use by the pregnant individual cannot be determined by these tests.
• Detection of drugs in meconium or umbilical cord tissue depends on the extent of maternal drug use, as well as drug stability in matrix, the unique characteristics of drug deposition in meconium and umbilical cord tissue, the quality and quantity of specimen submitted for testing, and the performance of the test method.
• Concordance of results between twins is higher in umbilical cord tissue than in meconium. 
• Minimum reporting limits and estimated concentrations are established for each compound, but quantitative results are not reported.