What can be expected from the cytologic examination of cervicovaginal smears for the diagnosis of Chlamydia trachomatis infections?

The value of Papanicolaou-stained smears for the diagnosis of chlamydial infections is still disputed. A comparative examination of smears from infected and uninfected women has allowed the proposal of a new scheme for the interpretation of the cytologic abnormalities associated with chlamydial infection. In particular, the appearances of metaplastic cells were classified, and two smear types were found to have the highest sensitivities and positive predictive values: smears in which the metaplastic cells had (1) intracytoplasmic vacuoles containing polymorphonuclear leukocytes or (2) numerous small intracytoplasmic vacuoles containing a central eosinophilic granule. The sensitivity of this method is low, however; cytology cannot replace bacteriologic identification for the diagnosis of chlamydial infections. Nevertheless, the examination of Papanicolaou-stained smears could be considered as a screening tool in low-risk populations; provided that all of the cytologic features were considered, presumptive diagnoses of chlamydial infections could be obtained.