Serology workflow: the VDRL (Venereal Disease Research Laboratory) test for syphilis is commonly performed as which procedural format?

Introduction / Context:
The VDRL test is a nontreponemal screening assay for syphilis that detects reagin antibodies against cardiolipin–lecithin–cholesterol antigen. Correctly identifying the test format helps in understanding its performance characteristics, interpretation, and limitations.

Given Data / Assumptions:

• VDRL is a nontreponemal test (screening).
• It uses a standardized antigen and observed flocculation.
• The question asks about the procedural format.

Concept / Approach:
VDRL is traditionally performed as a slide flocculation test. Patient serum (often heat-inactivated) is mixed with antigen on a glass slide and observed microscopically for flocculation. RPR is a related macroscopic cardiolipin test but uses charcoal particles for easier visualization.

Step-by-Step Solution:

Verification / Alternative check:
Standard lab manuals describe VDRL as a microscopic slide flocculation assay, with titers reported for reactive specimens.

Why Other Options Are Wrong:

• Tube/ring tests: Not the standard for VDRL.
• None of these / ELISA: Not correct; VDRL is not an ELISA.

Common Pitfalls:

• Confusing VDRL with RPR (both are nontreponemal but differ in visualization method).

Final Answer:
Slide test (flocculation on a glass slide)