Au680 automated chemistry platform

Since March 2015, obstetric clinics providing prenatal care within our health system have implemented routine urine toxicology screening for THC and other substances for all pregnant women (amphetamines, barbiturates, benzodiazepines, cocaine, methadone, opiates, oxycodone, phenylcyclidine) at the first prenatal visit, generally between 6 and 14 weeks’ gestation. If screening was not conducted at the first visit, it was completed later in the course of prenatal care. Urine specimens were routinely collected at the community-based outpatient obstetrics clinics. Specimens were then transported, processed and tested at a single hospital-based laboratory. The laboratory used SYVA EMIT immunoassay (Siemens Healthineers) with a cutoff of 50 ng/mL to detect 11-nor-Δ9-THC-9-COOH, a THC metabolite, on a Beckman AU680 automated chemistry platform. Positive immunoassays underwent reflex confirmatory testing by gas chromatography-mass spectrometry (GC-MS) selected-ion-monitoring (SIM). Urine creatinine was also tested and the urine toxicology screen was deemed invalid if the urine creatinine was <20 mg/dl. In cases where urine toxicology screens were repeated in the same pregnancy, exposure status was based on the results of the first urine THC screen.