87491

Chlamydia trachomatis Detection by Amplified Probe Technique

CPT code 87491 represents the laboratory analysis for the detection of Chlamydia trachomatis genetic material using an amplified nucleic acid probe technique, commonly referred to as Nucleic Acid Amplification Testing (NAAT). Chlamydia trachomatis is a Gram-negative, obligate intracellular bacterium and is one of the most common causes of sexually transmitted infections globally, leading to conditions such as urethritis, cervicitis, and pelvic inflammatory disease. The amplified probe technique is considered the gold standard for diagnosis due to its high sensitivity and specificity. Unlike direct probe techniques represented by CPT 87490, which only detect the presence of DNA or RNA through hybridization, the amplified technique involves the exponential replication of target genetic sequences. This process typically employs methodologies such as Polymerase Chain Reaction (PCR), Transcription-Mediated Amplification (TMA), or Strand Displacement Amplification (SDA). The laboratory procedure begins with the collection of a clinical specimen, which may be a vaginal swab, endocervical swab, male urethral swab, or a first-catch urine sample. Once the specimen is processed, nucleic acids are extracted and purified. Specific primers and enzymes are then introduced to amplify the target DNA or RNA unique to the Chlamydia organism. The presence of the amplified product is monitored in real-time or at the end-point using fluorescent markers. This amplification allows for the detection of very low concentrations of the pathogen, which is particularly beneficial for screening asymptomatic individuals or those in the early stages of infection. Results are reported qualitatively as 'detected' or 'not detected.'

Clinical Indications

  • Screening for Chlamydia in sexually active females under age 25
  • Screening in older women at increased risk of infection
  • Evaluation of symptoms such as dysuria, urethral discharge, or vaginal discharge
  • Assessment of pelvic inflammatory disease (PID)
  • Prenatal screening for sexually transmitted infections during the first and third trimesters
  • Contact tracing and testing of partners of known positive cases
  • Infertility workup for both males and females
  • Monitoring for infection in high-risk populations such as those with HIV

Procedure Steps

  1. Collect clinical specimen (swab or urine) using the specific collection kit required by the testing platform.
  2. Transport the specimen to the laboratory in appropriate transport media at required temperatures.
  3. Perform laboratory accessioning and verify specimen integrity.
  4. Extract nucleic acids (DNA or RNA) from the clinical sample using automated or manual extraction protocols.
  5. Prepare the amplification master mix including primers, probes, and polymerase enzymes.
  6. Execute the amplification cycle (e.g., thermal cycling for PCR) to replicate target Chlamydia trachomatis sequences.
  7. Monitor for signal detection (e.g., fluorescence) indicating the presence of amplified genetic material.
  8. Interpret results based on internal and external control standards.
  9. Finalize and release the qualitative report to the ordering provider.

Coding Guidelines

  • Report 87491 specifically for amplified probe techniques; do not use for direct probe (87490) or quantification (87492).
  • When testing for both Chlamydia and Neisseria gonorrhoeae using amplified probe techniques, report 87491 and 87591 as separate line items.
  • Ensure that the specimen type (e.g., urine vs. swab) is FDA-cleared for the specific laboratory assay being utilized.
  • Laboratory tests are not subject to modifier 51 (multiple procedures).
  • Check for bundled or multiplex codes if Chlamydia is part of a larger panel of infectious agents.
  • If the test is performed at the point of care using an amplified technique, verify if a QW modifier is required for CLIA-waived status on specific devices.

Associated ICD-10 Codes