Differences in coverage patterns in cervical cytology screening

Abstract

The visual screening of cervical smears is a complex process requiring appropriate slide coverage to detect any unusual appearances without making any omission errors. In examining a smear the observer has both to move the microscope stage appropriately to bring different slide areas into view, plus visually search the information presented within the binocular visual field. This study examined the patterns of slide coverage by different individuals when they inspected liquid based cervical smears. A binocular microscope was first adapted in order to record both the physical movement of the stage by the observer and also to access the microscope’s visual field. An image of the area of the smear under the microscope was displayed on a PC monitor and observers’ eye movements were recorded as they searched this. By manually adjusting the microscope controls they also moved the stage and all stage movements and focussing were also recorded. The behaviour was examined of both novices and an expert screener as they searched a number of test cervical smears. It was found that novices adopted a regular examination pattern, which maximized slide coverage, albeit slowly. In contrast, the experienced screener covered the slides faster and more effectively ensuring more overlap between microscope fields.