Abnormal Urine Drug Screens in Pregnancy- Opportunity for Laboratory Stewardship

Clinical testing for drugs of abuse typically involves initial screening followed by confirmatory testing. Due to limited evidence-based guidelines, the healthcare provider makes the decision to confirm abnormal screens based on the clinical context. This two-step approach proved to be inadequate in scenarios like maternal substance abuse and subsequent fetal/ newborn exposure. The goal of this study is to assess and improve the confirmatory testing rate of abnormal screens among pregnant patients at our women's center.

A retrospective chart review was conducted to assess the confirmation rates among positively screened pregnant patients, and a lab stewardship initiative was implemented to remind ordering physicians about the importance of confirmatory drug tests. Abnormal screens were classified as expected positives based on the medication-related interference, social history and self-reported substance use from the provider notes.

Only 28% of pregnant patients with unexpected positive drug screens underwent confirmatory testing during the pre- intervention period, which rose significantly to 67% during the post-intervention period. Furthermore, outcome analysis revealed that 50% of patients with concordant confirmatory test results were referred to social work and psychiatry in the post-intervention period.

This study highlights the value of laboratory stewardship in optimizing drug testing practices for pregnant patients.