1. A computer-assisted method of classifying cytological samples, comprising: using one or more processors to display previously unclassified cytological sample images to a reviewer, receive classifications of the displayed cytological sample images from the reviewer, monitor a reviewer classification rate equal to a number of displayed previously unclassified cytological sample images receiving a specified classification by the reviewer divided by a total number of previously unclassified cytological sample images displayed to the reviewer, and if the monitored reviewer classification rate is below a threshold rate, display to the reviewer, interspersed with the displayed previously unclassified cytological sample images, one or more images of the specified classification obtained from a database of images of previously classified cytological samples.