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Lab Test Details

Chlamydia trachomatis and Neisseria gonorrhea, TMA amplified

Updated6/27/2025
Other NamesChlamydia (CT) Combo Test; Chlamydia and Gonorrhea Screen; Gonorrheae (GC) Combo Test
How to OrderOn the Virology/Immunology Test Request Form (OHA0042), in the CT/GC section, choose the "Chlamydia/Gonorrhea by NAAT" box. Select specimen source under the test order.
AvailabilityAll clients
PerformedDaily on regular business days
Time to ReportingWithin 3 working days after receipt of specimen
CPT Code87801

Specimen Collection Details

CollectionAll patient-collected specimens must be collected in a healthcare setting.

Endocervical Specimens (clinician-collected only) – White Unisex Tube:

Urethral Specimens (clinician-collected only) – White Unisex Tube:

Vaginal Specimens (clinician-collected or patient-collected) – Orange Multitest Tube:

Urine Specimens – Yellow Urine Tube:

Rectal Specimens* (clinician-collected or patient-collected) – White Unisex Tube:

  • Patient Collection Instructions (pdf)
  • Insert the blue shaft swab 1 inch into the rectum and rotate against the rectal wall several times, approximately 5-10 seconds.
  • Immediately place the blue swab into the specimen transport tube. Break the swab at the score line. Recap the tube tightly.
  • Do not submit the white cleaning swab for testing.

Pharyngeal Specimens* (clinician-collected only) – White Unisex Tube:

  • Vigorously rub the tonsils and posterior pharynx with the blue shaft swab. The use of a tongue depressor may be helpful.
  • Carefully remove the swab, not touching any area of the mouth. Immediately place the blue swab into the specimen transport tube. Break the swab at the score line. Recap the tube tightly.
  • Do not submit the white cleaning swab for testing.
* The OSPHL has validated the modification of the current FDA approved procedure for CT/GC testing to include pharyngeal and patient- and clinician-collected rectal swabs. The instructions for these specimen sources may therefore differ from instructions provided by other laboratories.
Optimal Volume

Urine: 2 mL

Swabs: Ensure ~3.0 mL liquid media remains in tube

Minimum Volume

Urine: 2 mL

Swabs: Ensure ~3.0 mL liquid media remains in tube

Handling All sample types may be stored at refrigerated or ambient temperatures (4-30°C) pending transport.  All sample types are stable for 30 days. 
Transport Transport specimens at refrigerated or ambient temperatures.  All sample types are stable for 30 days. 
Rejection CriteriaIncorrect tube submitted for specimen source; Expired collection kits; Wrong volume of media or urine in tube; Wrong swab or no swab submitted; Specimens are subject to the requirements of the OSPHL Specimen Submission Policy (pdf).
Comments
 The performance of the Aptima Combo 2 Assay has not been evaluated in adolescents less than 14 years of age. Specimens in this age group will be tested. These results will include a descriptive comment.


First catch female urine specimens are acceptable but may detect up to 10% fewer CT/GC infections when compared with vaginal and endocervical swab specimens.


Original material submitted for testing is retained for 9 calendar days after receipt at the laboratory.


The OSPHL has validated the modification of the current FDA approved procedure for CT/GC testing to include rectal and pharyngeal swabs. Only specimen sources detailed in the OSPHL Instructions for CT/GC Testing document provided above are acceptable for testing at the OSPHL.

Method Details

MethodologyTranscription-Mediated Amplification; Nucleic Acid Hybridization
PerformanceSpecifications Endocervical, urethral, vaginal, and urine: Detailed data on assay performance for this test is available from the manufacturer, Hologic at: https://www.hologic.com/package-inserts/diagnostic-products/aptima-combo-2-assay-ctng

Clinician-Collected and Patient-Collected Pharyngeal Swabs, Chlamydia and Gonorrhea:

  • Percent accuracy: 100%
  • Positive Predictive Value: 100%
  • Negative Predictive Value: 100%
  • Coefficient of Variation: 0
  • Misclassification Rate: 0
  • Sensitivity: 100%

Patient-Collected Rectal Swabs, Chlamydia:

  • Percent accuracy: 97.03%
  • Positive Predictive Value: 94.44%
  • Negative Predictive Value: 98.46%
  • Coefficient of Variation: 0
  • Misclassification Rate: 0
  • Sensitivity: 97.14%

Patient-Collected Rectal Swabs, Gonorrhea:

  • Percent accuracy: 100%
  • Positive Predictive Value: 100%
  • Negative Predictive Value: 100%
  • Coefficient of Variation: 0
  • Misclassification Rate: 0
  • Sensitivity: 100%

Change Log

6/27/2025Requirements unchanged; Updates throughout for clarity
5/5/2023Clarified How to Order; Edited Comments
3/15/2021Reviewed; no changes made