Laboratory differences in cervical cytology

This prospective study was designed to determine if there is a difference in reporting endocervical cells in Papanicolaou smears among laboratories used by an urban, academic family practice. A review of the literature found no studies comparing Papanicolaou smear results among laboratories with respect to the presence of endocervical cells. In this study, three laboratories evaluated a total of 140 Papanicolaou smears from women aged 16 to 83 (mean = 33.8) for endocervical cells. The presence of endocervical cells was reported for 88 smears (62.9%) ranging from 42/83 (50.6%) to 21/23 (91.3%) among laboratories. Results of an analysis of variance revealed a statistically significant difference in the frequency of reporting endocervical cells (p less than .001) among the laboratories. Analysis of covariance controlling for effects of several factors known to influence the outcome of Papanicolaou smears (age, days since last menstrual period, method used to obtain smear, and experience of clinician obtaining smear) failed to explain this difference.