How Adequate is Adequate for the Collection of Endocervical Specimens for Chlamydia trachomatis Testing?

Background: Endocervical specimen adequacy has been assessed by subjective criteria that are based on arbitrarily chosen thresholds for the presence of target cells observed on microscopic slide examinations. Goal of this Study: To assess the relationship of chlamydia test positivity to specimen adequacy with the use of a semiquantitative cytologie staining method for assessing endocervical specimen collection cellularity. Study Design: Endocervical specimens for chlamydia testing (PACE 2, GenProbe, San Diego, CA) and for a slide cytologie examination (n = 3,500) were collected in parallel. A semiquantitative cytologie examination to determine a specimen adequacy (SA) score was performed for every chlamydiapositive result (n = 163) and approximately every fifth negative result (n = 626). The Chi-square test for linear trends was used to assess the relationship between SA scores and chlamydia positivity. The median SA scores for chlamydia-positive and negative slides were compared. Results: The median SA scores for chlamydia-positive and -negative slides were 27 and 20, respectively (P < 0.001). Chlamydia positivity rates increased with increasing specimen adequacy scores (0-9, 2.7%; 10-19, 15.1%; 20-29, 24.8%; and 30-45, 31.3%; Chi-square for linear trend: P < 0.001). Conclusion: These results demonstrate a linear relationship between the numbers of cells observed on an endocervical smear and chlamydia positivity rather than the threshold concept in practice. The semiquantitative cytologie technique offers an objective method for further evaluating specimen adequacy for Chlamydia trachomatis testing.