False-Positive Urine Ethyl Glucuronide Results in Pregnancy Caused by Escherichia coli Urinary Tract Infection.

BACKGROUND: Urine alcohol biomarker testing is commonly used to monitor alcohol use during pregnancy but may be difficult to interpret when results are discordant or influenced by physiologic or microbiologic factors. CASE: We describe a 27-year-old pregnant woman with opioid and methamphetamine use disorder, atypical preeclampsia, and recurrent Escherichia coli urinary tract infection who denied alcohol use. Repeated urine testing showed positive urine ethyl glucuronide with negative ethyl sulfate and ethanol. Whole-blood phosphatidylethanol testing confirmed no systemic alcohol exposure. Findings were consistent with postcollection bacterial synthesis of ethyl glucuronide in bacteriuric urine specimens. CONCLUSION: This case highlights the need for careful interpretation of alcohol biomarkers in perinatal addiction care because false-positive results may affect treatment decisions and child protective service involvement.