title: False-positive meconium test results for fatty acid ethyl esters secondary to delayed sample collection.
abstract: BACKGROUND
  Meconium analysis for fatty acid ethyl esters (FAEEs) is a validated method for identifying heavy prenatal ethanol (EtOH) exposure. This study investigated whether delayed sample collection can result in false-positive test results for FAEEs because of collection of samples potentially contaminated with postnatally produced stool.
  
  
  METHODS
  Serial excretions were prospectively collected from neonates born to nondrinking mothers to capture the transition from meconium to postnatal stool. These were analyzed for FAEEs using headspace-solid phase microextraction and gas chromatography-mass spectrometry. Experiments involving incubation of samples with glucose or EtOH were performed to explore a potential mechanism of FAEE elevation.
  
  
  RESULTS
  A total of 136 samples were collected from 30 neonates during their first few days of life (median of 4 samples/baby over a mean period of 68.5 hours postpartum). Although the first-collected meconium sample tested negative for FAEEs in all babies, later samples tested above the 2 nmol/g positive cutoff in 19 of 30 babies. Median time to appearance of FAEE-positive samples was 59.2 hours postpartum. In vitro experiments demonstrated that FAEE levels can be further increased in late samples (likely containing postnatal stool) after incubation with glucose, and that FAEEs are readily formed in meconium in the presence of EtOH.
  
  
  CONCLUSIONS
  Collection of samples excreted later in the postpartum period can lead to false-positive test results for FAEEs, which could be because of contamination with dietary components of postnatally produced stool and EtOH-producing microorganisms. Clinically, it is critical to collect the earliest possible excretion for determination of FAEEs to ensure that the FAEE content is representative of in utero EtOH exposure.
authors.affiliation: Division of Clinical Pharmacology & Toxicology, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Irene
authors.initials: I
authors.lastname: Zelner
authors.forename: Janine R
authors.initials: JR
authors.lastname: Hutson
authors.forename: Bhushan M
authors.initials: BM
authors.lastname: Kapur
authors.forename: Denice S
authors.initials: DS
authors.lastname: Feig
authors.forename: Gideon
authors.initials: G
authors.lastname: Koren
mesh_terms: D000328:Adult; D002241:Carbohydrates / Q000737:chemistry; D002492:Central Nervous System Depressants / Q000378:metabolism*; D004952:Esters / Q000032:analysis; D000431:Ethanol / Q000378:metabolism*; D005189:False Positive Reactions; D005227:Fatty Acids / Q000032:analysis*; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005260:Female; D063647:Fetal Alcohol Spectrum Disorders; D008401:Gas Chromatography-Mass Spectrometry; D005947:Glucose / Q000737:chemistry; D006801:Humans; D007231:Infant, Newborn; D008049:Lipase / Q000032:analysis; D008470:Meconium / Q000737:chemistry*; D011247:Pregnancy; D011446:Prospective Studies; D052617:Solid Phase Microextraction
chemical_list: D002241:Carbohydrates; D002492:Central Nervous System Depressants; D004952:Esters; D005227:Fatty Acids; D000431:Ethanol; D008049:Lipase; D005947:Glucose