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Gonorrhea-Chlamydia (GC-CT), Amplified RNA Probe

Laboratory Fee Schedule
Procedure: MBB0191A
CPT: 87491, 87591

Synonym(s): Gonorrhea, Chlamydia, Neisseria gonorrhoeae, Chlamydia trachomatis, Combo 2, GC/CT NAAT, Screen 
Requisition Form G-2B
Test Description Target amplification nucleic acid probe test that utilizes target capture for qualitative detection and differentiation of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT) and/or Neisseria gonorrhea (GC)
Pre-Approval Needed N/A
Supplemental Information Required N/A
Supplemental Form(s) N/A
Performed on Specimens from (sources) Human
Sample/Specimen Type for Testing The following specimen types may only be collected using the collection kit listed for each:
  • Vaginal swab - Aptima® Multitest Swab Collection Kit
  • Endocervical swab - Aptima® Unisex Swab Collection Kit
  • Urethral swab - Aptima® Unisex Swab Collection Kit
  • Urine - Aptima® Urine Specimen Collection Kit
  • Rectal swab - Aptima® Multitest Swab Collection Kit
  • Throat swab - Aptima® Multitest Swab Collection Kit
Minimum Volume/Size Required One correct swab or urine filled between the two black indicator lines on the tube label
Storage/Preservation Prior to Shipping

Endocervical, Vaginal, and Urethral Swabs

  • Store swab in transport tube at 2°C to 30°C for up to 60 days after collection.
  • For long term storage, freeze swab in transport tube at -20°C to -70°C within 7 days of collection.

Rectal and Throat Swabs

  • Store swab in transport tube at 4°C to 30°C OR at -20°C to -70°C for up to 60 days.

Urine Specimens

  • Store specimen in transport tube at 2°C to 30°C for up to 30 days.
  • For long term storage, freeze at -20°C to -70°C within 7 days of collection for testing up to 12 months after collection. 
Transport Medium N/A
Specimen Labeling
  • Two patient-specific identifiers required on specimen (e.g., patient full name, date of birth, medical record number)
  • Three patient identifiers are preferred.
  • Patient identifiers on specimen label must exactly match identifiers on submission form (e.g., abbreviated name on label and full name on form is not acceptable.)
  • Additional DSHS Laboratory specimen labeling guidelines available online here.
Shipping and Specimen Handling Requirements
  • Ship according to Dangerous Goods Regulations, IATA, and/or CFR 49.
  • Category B Biological Substance, UN3373 shipping requirements apply.
  • Handle as infectious agent using universal precautions. 
  • Triple-contain in accordance with federal shipping regulations for infectious agents.  
  • Submitters are responsible for packaging and shipping specimens according to regulatory requirements.
  • Additional DSHS Laboratory specimen shipping guidelines online here.
Method Target amplification nucleic acid probe test
Turn-around Time 3 working days
Interferences/Limitations
  • Reliable results are dependent on adequate specimen collection.
  • A negative result does not preclude a possible infection. 
Common Causes for Rejection
  • Unacceptable specimen type or source.
  • Improper shipping conditions.
  • Urine specimen (stored at 2°C to 30°C) older than 30 days. 
  • Swab specimen older than 60 days.
  • Specimen collected using the wrong collection kit.
  • Urine specimen not transferred to transport tube. 
  • No swab in transport tube.
  • Two swabs in transport tube.
  • Swab used to collect specimen not supplied by Hologic.
  • Urine not filled to between the two black indicator lines on tube label.
  • Expired reagents/media/collection container.
  • Discrepancies between G-2B submission form and specimen label.
  • Missing/incomplete/illegible submission form or label.
Additional Information Results from the APTIMA COMBO 2 Assay should be interpreted in conjunction with other laboratory and clinical data available to the clinician.