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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Chlamydia trachomatis by Amplified Probe Technique

Test Code(s): CTAPT / HCCTAPT

CPT Code(s): 87491

Methodology: Amplified Probe Technique

Clinical Significance: Detection of Chlamydia trachomatis by Amplified Probe Technique. Concommitant testing for Neisseria gonorrhoeae by Amplified Probe Technique is highly recommended.

Days Performed: Mon-Fri.

Turnaround Time: Stat: Not available stat.
Routine: Up to 2 working days.

Specimen Requirements

Specimen: Females: Endocervical or vaginal swab or urine. Males: Urethral swab (symptomatic males only) or urine.

Collection Instructions: Swab Specimens:

Obtain room temperature APTIMA Collection Kit from the UWHC Central Services. Follow instructions included with the APTIMA Collection Kit (must use swabs provided).
UWHC Central Services Numbers:
Endocervical, item #4013141
Male urethral, item #4013141
Male and Female urine, item #4013143
Vaginal, item #4013142

Females: Remove and discard any excess mucus, blood, or examination lubricants prior to collection of cervical specimen.

Male Urethral swabs: Patient should not urinate for at least 1 hour prior to collection of specimen.

Insert unisex swab into the cervix or urethra and rotate 10-30 seconds. Place swab in the APTIMA Collection Kit tube and close cap. Do NOT place large white cleaning swab in APTIMA Collection Kit tube.

Specimen may be stored at 2-30C for up to 7 days.

Urine Specimens:

Patient should not urinate for at least 1 hour prior to collection of urine specimen. Collect the first 10-50 mL of first catch urine into polypropylene container without preservatives. Female patients should not cleanse the labial area prior to providing the specimen. Midstream urine or >50 mL may increase the chance of false negative results.

Urine specimens should be transferred to the APTIMA urine collection kit or sent in a sterile urine container. Urine specimens must be transferred to the kit within 24 hours of collection.  APTIMA urine transport tubes must be filled between the two indicator lines on the tube.

Urine specimens not in APTIMA Urine Specimen Transport are stable for 24 hours at 2-30C. Specimens stored in the APTIMA Urine Specimen Transport are stable for 7 days at 2-30C.

Collection Container: Preferred: APTIMA Collection Kit

Sample Analyzed: See collection instructions.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220) as soon as possible.

Unacceptable Criteria: Swab must remain in the APTIMA Collection Kit or specimen is unacceptable and must be recollected. Female urethral, wooden swabs, or swabs with aluminum shafts are also unacceptable.

APTIMA Collection Kit Tubes containing both unisex swab and large white cleaning swab or large white cleaning swab only are unacceptable.

Catheter-collected urine specimens are not acceptable.

APTIMA Collection Kits that have been punctured.

Urine specimens in APTIMA urine transport that are not filled between the two indicator lines on the transport tube.

Stability: Ambient: See collection instructions
Refrigerated: See collection instructions
Frozen: Not Acceptable


Reference Interval:

Age 0 days and up: Negative

Test Limitations:

Chlamydia trachomatis by Amplified Probe Technique has been validated for female endocervical and vaginal swabs, urethral swabs from symptomatic males, and male and female urine.


For reliable test results, follow instructions for proper specimen and transport conditions.

Additional Information:

For conjunctival specimens, see test directory entry for Chlamydia trachomatis by Amplified Detection, Conjunctiva specimen [HCCTEYE].


Culture is the only forensically acceptable method for sexual assault and abuse cases.


Culture should also be used for post-hysterectomy females who lack a cervix.


Culture MUST be used for pharyngeal (throat), rectal (anal), and semen specimens. See Culture, Chlamydia trachomatis.


Repeat sampling for test of cure is generally not recommended.


A minimum of 3 weeks must elapse following treatment before repeat testing.


This test was performed using a modification of an FDA approved method. The performance characteristics of this test were determined by the UWHC Clinical Laboratories and meet the standards for clinical testing.


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