Assessing the clinical utility of toxicology testing in the peripartum period

Background: Toxicology testing is frequently used as a means of gathering objective data about substance use in pregnancy, but little is known about the clinical utility of testing in the peripartum setting.

Objective: This study aimed to characterize the utility of obtaining maternal-neonatal dyad toxicology testing at the time of delivery.

Study design: We performed a retrospective chart review of all deliveries in a single healthcare system in Massachusetts between 2016 and 2020, and identified deliveries with either maternal or neonatal toxicology testing at delivery. An unexpected result was defined as a positive test for a nonprescribed substance that was not known on the basis of clinical history, self-report, or previous toxicology testing within a week of delivery, excluding results for cannabis. We evaluated the characteristics of maternal-infant dyads with unexpected positive results, unexpected positive results by rationale for testing, changes in clinical management after an unexpected positive test, and maternal outcomes in the year after delivery using descriptive statistics.

Results: Of the 2036 maternal-infant dyads with toxicology tests performed during the study period, there were 80 (3.9%) with an unexpected positive result. Diagnosis of substance use disorder with active use in the last 2 years was the clinical rationale for testing that yielded the greatest number of unexpected positive results (10.7% of total tests ordered for this rationale). Inadequate prenatal care (5.8%), maternal use of medication for opioid use disorder (3.8%), maternal medical indications such as hypertension or placental abruption (2.3%), history of substance use disorder in remission (1.7%), or maternal cannabis use (1.6%) yielded lower rates of unexpected results compared with a recent substance use disorder (within the last 2 years). Solely on the basis of findings from unexpected test results, 42% of dyads were referred to child protective services, 30% of dyads had no documentation of maternal counseling during delivery hospitalization, and 31% did not receive breastfeeding counseling after an unexpected test; 22.8% had monitoring for neonatal opioid withdrawal syndrome. Postpartum, 26 (32.5%) were referred to substance use disorder treatment, 31 (38.8%) attended a postpartum mental health visit, and only 26 (32.5%) attended a postpartum visit. Fifteen individuals (18.8%) were readmitted in the year after delivery, all for substance-related medical complications.

Conclusion: Unexpected positive toxicology results at delivery were uncommon, particularly when tests were sent for frequently used clinical rationales for testing, suggesting a need to revisit guidelines surrounding appropriateness of indications for toxicology testing. The poor maternal outcomes in this cohort highlight a missed opportunity for maternal connection to counseling and treatment in the peripartum period.