Effect of specimen order on Chlamydia trachomatis and Neisseria gonorrhoeae test performance and adequacy of Papanicolaou smear.
OBJECTIVE
To evaluate the effect of specimen collection order on the performance of diagnostic tests for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC), and the specimen adequacy of ThinPrep Papanicolaou (Pap) smears.


METHODS
Prospective cohort study.


METHODS
Public adolescent clinic.


METHODS
313 women.


METHODS
The order of five cervical testing specimens was randomized for (1) ligase chain reaction (LCR) and (2) polymerase chain reaction (PCR) for both CT and GC; (3) transcription-mediated amplification (TMA) for CT; (4) culture for CT; and (5) cytology and LCR for GC and CT performed on ThinPrep Pap specimens. For CT and GC, a reference standard was based on three different tests performed on separate specimens. Generalized estimating equations were used to account for repeated measures.


METHODS
Sensitivity and specificity of diagnostic tests.


RESULTS
The proportion of inadequate Pap smears was independent of specimen order. As a group, nucleic acid amplification test (NAAT) sensitivity and specificity for GC and CT were similar in the first two (early) and last three (late) swabs. Although point estimates for sensitivity were higher in the early swabs compared to the late swabs for GC LCR (13% difference), GC PCR (13%), and CT TMA (10%), these differences were not statistically significant. Their clinical significance warrants further investigation.


CONCLUSIONS
In clinical settings where both Pap smears and STI testing are performed in adolescents, clinical considerations can influence the order of specimen collection, since neither Pap specimen adequacy nor test performance of NAAT for CT and GC were significantly associated with swab order.
Johns Hopkins University School of Medicine, Bayview Medical Center, 4940 Eastern Avenue B3 North, Baltimore, MD 21224, USA. kghanem@jhmi.edu
Khalil G
KG
Ghanem
Emilia H
EH
Koumans
Robert E
RE
Johnson
Mary K
MK
Sawyer
John R
JR
Papp
Elizabeth R
ER
Unger
Carolyn M
CM
Black
Lauri E
LE
Markowitz
D000293:Adolescent; D002690:Chlamydia Infections / Q000175:diagnosis*; D002692:Chlamydia trachomatis / Q000302:isolation & purification*; D015331:Cohort Studies; D005260:Female; D006069:Gonorrhea / Q000175:diagnosis*; D006801:Humans; D008137:Longitudinal Studies; D009344:Neisseria gonorrhoeae / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques; D065006:Papanicolaou Test; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D014626:Vaginal Smears / Q000379:methods* / Q000592:standards