Test Name
PHL Location
Amplified Nucleic Acid Test for Chlamydia trachomatis and
Neisseria gonorrhoeae
Central Laboratory
CPT Code
87591, 87491
Synonyms
CT/GC, Gonorrhea/Chlamydia, or Gen-Probe test
Brief Description of Test
The APTIMA Combo 2 Assay is a target amplification nucleic acid
probe test for the in vitro qualitative detection of Chlamydia
trachomatis and Neisseria gonorrhoeae using the TIGRIS DTS
Automated Analyzer
Aptima CT Results
CT Pos
CT Neg
CT Equiv
CT Invalid
Interpretation
Positive for CT
rRNA
Presumed negative
for CT rRNA
Indeterminate, a
new specimen
should be collected
Invalid
Reported
Detected
Interpretation
Positive for
GCrRNA
Presumed negative
for GC rRNA
Indeterminate, a
new specimen
should be collected
Invalid
Reported
Detected
Not Detected
Inconclusive, a new
sample should be
collected
Collection Error.
Mucoid Sample. A
new sample should
be collected.
Possible Results
Aptima GC Results
GC Pos
GC Neg
GC Equiv
GC Invalid
Reference Range
Specimen Type
Not Detected
Inconclusive, a new
sample should be
collected
Collection Error.
Mucoid Sample. A
new sample should
be collected.
Not Detected
Endocervical or male urethral swab, urine
Specimen Container(s):
Aptima Unisex swab and Aptima Urine collection kit - Contact
Central Lab to obtain kits.
Minimum Volume:
Liquid levels in urine specimen must fall between the two black
indicator lines on the urine transport tube label.
Collection Instructions
Storage and Transport
Instructions
For Urine, Endocervical or Urethral Specimens:
Only swabs contained in the Aptima Specimen Collection kits can
be used to collect patient specimens. Swabs collected from patients
MUST be transported to the lab in the GEN-PROBE transport
medium. Follow instruction for collection provided with collection
kit.
Swab specimens must be transported to the laboratory at 2ºC to
30ºC and tested within 60 days of collection. Urine specimens in
urine collection tubes must be transported to the laboratory at 2ºC
to 30ºC and tested within 30 days after collection. Prevent crosscontamination by packaging in the multi-compartment bubble wrap
pouches or put each specimen into a separate leak-proof specimen
bag before placing in coolers for shipment.

Two swabs or no swab in tube

White swab in specimen tube (any swab other than the blue
swab

Insufficient specimen volume received or overfilled urine
tube (liquid levels in urine specimen must fall between the
two black indicator lines on the urine transport tube label)

Urine specimen received in the laboratory more than 30
days after collection date, swab specimen received in the
laboratory more than 60 days after collection date

Inadequate identification on specimen

Specimen submitted in expired transport or inappropriate
collection kit

Specimens packaged so that they are in direct contact with
each other causing cross contamination

Specimens collected from the eye
Causes for Rejection
Limitations of the
Procedure
A negative test result does not exclude the possibility of infection
because tests results may be affected by improper specimen
collection, handling, transport, technical error, specimen mix-up or
concurrent antibiotic therapy. Additionally, the concentration of
organisms may be below the sensitivity of the test. Results from the
Gen-Probe Aptima System should be used in conjunction with other
clinical data available to the clinician. If the clinical indication
strongly suggests infection, additional specimens should be
collected for further testing. Identification methods can yield false
positive results. In those instances additional testing is
recommended.
Interfering Substances
References
Additional Information
Excessive temperatures, Patient on antibiotic therapy, Inappropriate
collection techniques, see package inserts from Gen-Probe
APTIMA Combo 2 Collection Kits.
 Center for Disease Control, National Center or HIV, STD,
TB Prevention, Division of Sexually Transmitted Disease

None
Gen-Probe Incorporated, San Diego, California, package
inserts