Predictors of an unsatisfactory conventional cervical cytology smear

Cervical cytology smears reported as unsatisfactory for interpretation represent an unrealized screening opportunity and may have significant laboratory and patient costs. Identifying patients at higher risk for an unsatisfactory smear could alert clinicians to take extra care in the acquisition of the smear. Few studies have examined patient characteristics that could predict an unsatisfactory cervical cytology smear. The purpose of this study was to determine the effect of patient age, day of the menstrual cycle, postmenopausal status, postpartum status, and the use of oral contraceptives on the rate of unsatisfactory cervical cytology smears.

We performed a case-control study of all unsatisfactory cervical cytology smears at a large tertiary care teaching hospital over one year compared with a random sample of smears that were satisfactory for interpretation. Data were obtained from the cytology requisitions. Continuous variables were tested with unpaired t tests, and dichotomous variables were analyzed with chi-square tests. Multivariate significance was tested with binary logistic regression analysis.

Of all cervical cytology smears, 1.1% were reported as unsatisfactory. In univariate analyses increased age, earlier date in the menstrual cycle, and postpartum status were associated with unsatisfactory smears. However, following Bonferroni correction for multiple comparisons and multivariate regression analysis, only increased age remained a significant predictor of an unsatisfactory cervical cytology smear.

Older women are at greater risk of having an unsatisfactory cervical cytology smear. Clinicians and public health officials must be aware of this risk and must encourage optimal collection techniques for women in this demographic group.