What preparation is needed for rectal swab and oral pharyngeal swab collection for Chlamydia (Chlamydia trachomatis) and Gonorrhea (Neisseria gonorrhoeae) Polymerase Chain Reaction (PCR) testing?

Specimen Collection for Rectal and Oropharyngeal Chlamydia and Gonorrhea PCR Testing

No special patient preparation is required before collecting rectal or oropharyngeal swabs for Chlamydia trachomatis and Neisseria gonorrhoeae PCR testing. However, following proper collection technique is essential for accurate results.

Collection Materials

• Use swabs with plastic or wire shafts (not wooden shafts, which may contain substances toxic to chlamydia) 1
• Swab tips can be made of cotton, rayon, dacron, or calcium alginate 1
• Use laboratory-provided transport devices specific for nucleic acid amplification tests (NAATs) 1

Oropharyngeal (Pharyngeal) Swab Collection

1. No preparation needed before collection
2. Proper technique:
   • Swab the posterior pharynx and tonsillar areas
   • Avoid touching the tongue, teeth, or gums
   • Place swab in appropriate transport medium immediately after collection
3. Transport considerations:
   • Room temperature storage is acceptable
   • Follow laboratory-specific instructions for optimal transport time (typically within 24-48 hours) 1

Rectal Swab Collection

1. No preparation needed before collection
2. Proper technique:
   • Insert swab approximately 2-3 cm into the rectum
   • Rotate the swab against the rectal wall for 10-30 seconds to ensure adequate sampling
   • Withdraw carefully and place in appropriate transport medium
3. Transport considerations:
   • Room temperature storage is acceptable
   • Follow laboratory-specific instructions for optimal transport time (typically within 24-48 hours) 1

Important Considerations

• Self-collected rectal swabs have shown comparable sensitivity and specificity to clinician-collected samples, with agreement rates of 98% for both CT and NG in MSM 2
• For pharyngeal specimens, self-collected samples have shown sensitivities of 88-100% and specificities of 87-92% compared to clinician-collected samples 3
• NAATs are the preferred diagnostic method for detecting both Chlamydia trachomatis and Neisseria gonorrhoeae infections, with higher sensitivity than culture methods 4
• The same transport medium can typically be used for both chlamydia and gonorrhea testing 1

Common Pitfalls to Avoid

1. Using wooden-shaft swabs (can inhibit organism viability) 1
2. Inadequate sampling (not reaching the posterior pharynx or not inserting rectal swab sufficiently)
3. Improper storage (specimens should not be stored at -20°C or in "frost-free" freezers) 1
4. Delayed processing (follow laboratory guidelines for maximum transport time)

Testing Recommendations

The CDC and USPSTF recommend screening for chlamydia and gonorrhea in:

• All sexually active women under 25 years
• Women over 25 with risk factors
• Men who have sex with men (rectal and pharyngeal sites) 1

Following these collection procedures will help ensure accurate diagnosis and appropriate treatment of these infections, reducing morbidity and preventing complications such as pelvic inflammatory disease, chronic pelvic pain, and infertility.