Short interval between two Pap smears: effect on the result of the second smear? A prospective randomized trial.

Abstract

A repeat Pap smear is sometimes necessary after a short time interval or even immediately, when patients seek for a second opinion or due to study participation. Only limited information is available on the possible impact of a short interval between two Pap smears. Most institutions therefore practice a minimum time span of 6-8weeks before obtaining a second smear since a short interval is commonly believed to be associated with an increase of false negative results in the second smear. Two consecutive Pap smears were obtained from 81 women. 41 smears were processed using the conventional technique, whereas liquid-based cytology was used in the remaining 40 women. Smears were independently evaluated by four different cytopathologists. We analyzed the effect of time interval, both processing techniques and inter-observer variance in cytological evaluation. While the result of the second smear shows a tendency towards a more benign outcome (odds ratio (OR) 1.436, 95% CI 0.972-2.121), this difference was not statistically significant (p=0.07). No significant differences were observed between conservative and liquid-based cytology (OR 1.554, 95% CI 0.659-3.667, p=0.31). There was considerable inter-observer variability, and the observer was a strong predictor of the cytological result (OR 0.632-5.083, 95% CI 0.355-8.975, p<0.01). We document a tendency towards a more benign outcome without statistical significance in the second smear. Inter-observer variability of different cytopathologists is high and should be kept in mind when evaluating cytology results.