What distinguishes a screening sequence from reflex testing in drug analysis?

What distinguishes a screening sequence from reflex testing in drug analysis?

• A. Reflex testing is performed before screening
• B. Screening first using a broad immunoassay; if positive, reflex to confirmatory testing
• C. Reflex testing replaces the initial screen
• D. Screening and reflex testing are the same

Answer: (B)

In drug analysis workflows, screening sequences use a broad, sensitive test to cast a wide net and flag potential positives quickly, typically an immunoassay. When this initial screen yields a positive result, laboratories automatically perform reflex testing with a highly specific confirmatory method, such as GC-MS or LC-MS/MS, to identify the exact drug and verify its presence. This two-step approach minimizes false positives and provides results that are reliable for reporting.

Choosing to perform reflex testing before screening would miss the purpose of the initial broad screen. Treating reflex testing as replacing the initial screen ignores the need for wide detection, and treating screening and reflex testing as the same step misrepresents their distinct roles in detection versus confirmation.