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The presence of genital infection does not increase the likelihood of an inadequate Papanicolaou (Pap) test.1 Conversely, testing for Chlamydia trachomatis at the time of routine cytological screening presents an opportunity to detect asymptomatic genital tract infection.2 The PreservCyt fixative fluid (Cytyc Corporation, Boxborough. MA, USA) used for the ThinPrep Pap test (Cytyc Corporation) can be used for detection by the polymerase chain reaction (PCR) of C trachomatis.3,4 This presents an opportunity to study the correlation between the chlamydia result and the Pap test finding.
We retrospectively reviewed all routine requests for chlamydia PCR on ThinPrep samples sent to our laboratory over a year. Data were collected on the woman’s age, chlamydia PCR result, result of genital tract cultures if performed on the same date, and Pap test result. Data on the Pap test result included presence or absence of an epithelial cell abnormality either high grade (HGEA) or low grade (LGEA), whether the Pap was inflammatory and the presence or absence of recognisable pathogens. Cervical specimens collected in PreservCyt transport medium were processed for C trachomatis using the automated Cobas Amplicor (Roche Diagnostic Systems) and the method by Bianchi et al.3
Over the study period, 733 samples were received, of which 23 (3.1%) had C trachomatis DNA detected by PCR. Comparison of the women with chlamydia infection, with those without chlamydia infection is shown in table 1. There was no statistical difference in the presence of high or low grade epithelial abnormalities, recognition of other pathogens, or age of the women; however, 26% of women with chlamydia had an inflammatory Pap test compared to 9% of women without chlamydia (p<0.01).
The association of inflammation on Pap testing and chlamydial infection has been previously examined with variable methodologies and findings.5 We utilised the same sample (ThinPrep) for determining both the presence of inflammatory changes on Pap test and chlamydia infection and found a positive association between the two despite a low prevalence population. Our study confirms the feasibility of performing chlamydia PCR from liquid based cytology samples in a routine diagnostic setting. Testing for chlamydia should be considered in women with inflammatory Pap tests for which there is no other explanation.
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