Morphine, Meconium

Laboratory assay overview

This definitive drug assay is used to confirm in utero opioid exposure and identify the specific opioid(s) with gas chromatography/mass spectrometry [1]. Opioids included in this panel are codeine, morphine, hydrocodone, hydromorphone, and oxycodone. This test does not detect fentanyl, a major contributor to fatal overdoses in the United States [2]. Meconium begins to form around 12 weeks' gestation and accumulates mostly during the last trimester. Opioids used by mothers, and opioid metabolites, may deposit in meconium by diffusing across placentas or fetuses swallowing amniotic fluid. Adverse effects of in utero opioid exposure include preterm birth, low birthweight, birth defects, and neonatal opioid withdrawal syndrome. The clinical presentation of neonates varies by opioid type, maternal drug history, and other factors. Maternal self-reporting of opioid intake may be unreliable. Therefore, confirming opioid exposure via meconium testing can provide information necessary for clinical management of affected neonates [1,3,4]. The American Academy of Pediatrics recommends that meconium, urine, and umbilical cord tissue should all be considered for opioid testing. However, neonatal urine reflects only recent opioid exposure; umbilical cord tissue, though easy to collect, is not well understood as a specimen for opioid testing. For mothers who receive frequent toxicology testing to monitor treatment of opioid use disorder, meconium or umbilical cord tissue opioid testing does not provide additional clinical information and may not be necessary [4]. Results equal to or greater than the cutoff value for each opioid are reported as quantitative values and indicate in utero exposure; results less than cutoff are reported as negative. Because the frequency of drug use during pregnancy may affect detection of drugs in meconium, negative results do rule out in utero exposure to opioids [1]. The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings. ⁠⁠⁠⁠⁠⁠⁠References 1. Langman LJ, et al, eds. Using Clinical Laboratory Tests to Monitor Drug Therapy in Pain Management Patients. American Association for Clinical Chemistry; 2018. Accessed October 1, 2021. https://www.aacc.org/-/media/Files/Science-and-Practice/Practice-Guidelines/Pain-Management/LMPGPain-Management20171220.pdf?la=en&hash=19670524407619F78999AB60731A24CB4901939D 2. Wilson N, et al. MMWR Morb Mortal Wkly Rep. 2020;69(11):290-297. 3. About opioid use during pregnancy. Centers for Disease Control and Prevention. Accessed November 2, 2021. https://www.cdc.gov/pregnancy/opioids/basics.html 4. Patrick SW, et al; Committee on Fetus and Newborn; Committee on Substance Use and Prevention. Pediatrics. 2020;146(5).