TCH Logo Tarangnan Community Hospital Clinical Laboratory • Serology Section Document No.: WI-S-003-A-V0 CONTROLLED COPY
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Parent document: SOP-S-003, Sections 5.3–5.6  |  Version: V0
Applies to: Medical Technologists and Laboratory Aides  |  Effective date: MM-DD-YYYY  |  Supersedes: None

Syphilis Rapid Treponemal Cassette & RPR Flocculation Card Bench Aid

Sequential Testing Algorithm • Ambient Temperature Control (23–29 °C) • RPR Titration • SPH Referral

BIOSAFETY: Wear gloves; discard droppers/cassettes into biohazard/sharps waste; decontaminate spills per waste SOP.
Part A: Rapid Treponemal Antibody Lateral-Flow Cassette
  1. 1
    Specimen & Buffer Loading: Equilibrate cassette and serum to 15–30 °C. Dispense exactly 10 µL (or 1 drop) of serum into sample well (S). Immediately add 2 to 3 drops (80–100 µL) assay buffer. Start timer. SOP 5.3.2
    10 µL + buffer
  2. 2
    Result Reading & Maximum Limit: Read visually at 15 to 20 minutes. STOP Do NOT read after 20 minutes. If non-reactive but early primary syphilis is clinically suspected, order RPR (and consider repeat treponemal testing). If reactive, proceed immediately to RPR card testing. SOP 5.3.3–4
    15–20 min
Part B: Rapid Plasma Reagin (RPR) 18 mm Flocculation Card & Serial Titration
  1. 3
    Temperature & Serum Spreading: Verify bench temperature is 23 °C to 29 °C (73–85 °F). Dispense exactly 50 µL unheated serum into an 18 mm circle of RPR card. Spread evenly to fill circle without crossing line. SOP 5.2.3 / 5.4.2
    23–29 °C Log
  2. 4
    Carbon Antigen Addition: Invert antigen bottle gently. Hold bottle strictly vertical and dispense exactly 1 free-falling drop (17 µL) of carbon antigen into center of serum pool (needle calibrated 60 ± 2 drops/mL). Do NOT restir. SOP 5.4.2
    1 drop (17 µL)
  3. 5
    Mechanical Rotation & Reading: Place card on rotator, cover with humidifying cover, and rotate for exactly 8 minutes at 100 rpm. Remove immediately, tilt card 3–4 times by hand, and read macroscopically under high-intensity light. SOP 5.4.2
    8 min @ 100 rpm
  4. 6
    Quantitative Titration & Prozone Check: For every reactive/weakly reactive qualitative RPR, perform 2-fold serial dilutions (1:1, 1:2, 1:4, 1:8, 1:16, 1:32) in 0.9% saline. If neat serum looks rough/grainy, suspect prozone; test 1:4 and 1:16. SOP 5.4.4–5
    Serial Titer
TREP REACTIVE
S T C
Both C & T lines. Run RPR card.
TREP NON-REACTIVE
S T C
C line only. Report Non-Reactive.
RPR REACTIVE (R)
Large/medium carbon clumps. Perform serial dilution titer.
RPR WEAK (W)
Fine dispersed carbon flakes. Titrate for endpoint.
RPR NONREACTIVE
Uniform Grey
Smooth uniform grey suspension, no visible clumps.

Environmental & QC Governance (SOP 5.2 / 5.5)

  • Temperature Limit: Strictly 23 °C to 29 °C. <23 °C causes false negatives; >29 °C causes evaporation false positives.
  • Daily RPR Controls: Test Reactive, Weakly Reactive, and Nonreactive control sera daily with every batch.
  • Needle Calibration: Verify weekly: 1.0 mL distilled water = 60 ± 2 free-falling drops.

Confirmatory Referral Protocol (SOP 5.6.2)

  • Referral Trigger: Any reactive treponemal cassette or reactive RPR card.
  • Referral Facility: Samar Provincial Hospital (SPH) or NRL for TP-PA / FTA-ABS.
  • Specimen Aliquot: Minimum 1.0 mL clear serum at 2 to 8 °C in triple packaging.
  • Statutory Notification: Report reactive cases under RA 11332; notify clinician immediately.
Prepared by: Chief Medical Technologist
Signature / Date: ____________________		 Reviewed by: Pathologist
Signature / Date: ____________________		 Approved by: Hospital Director
Signature / Date: ____________________