| Abstract: | Background: Liquid based cytology (LBC) is the method of choice for the processing of samples in the cervical screening programme in England and Wales. Two LBC systems are in use; ThinPrep® and SurePath®. The manufacturers of SurePath® recommend that slides are screened in two separate directions perpendicular to each other (bidirectional screening) during the initial learning period. There is currently no evidence to evaluate whether this method is superior to screening in one direction only (unidirectional). Objectives: To compare the detection rate of high‐grade dyskaryosis in SurePath® preparations between screeners who used a unidirectional method and screeners who used a bidirectional method, to see if the screening method influenced detection rate. Methods: A questionnaire was sent to 23 screening staff at our Cytology Centre in October 2005, enquiring as to the method they used to screen SurePath® slides, as well as the grade of staff and the number of years experience they had screening cervical cytology slides. The staff were divided into two groups based on whether they screened unidirectionally or bidirectionally. A retrospective computerised search of all the slides screened by the staff for the period September 2004 to August 2005 was carried out, and the high‐grade detection rate at primary screening for the groups were calculated. Further analysis was carried out to determine the statistical significance of any difference between the two groups, as well as to account for potential confounding factors. Results: Initial results suggesting a statistically significant difference between the screening methods were later shown to be confounded by experience. Critical analysis of the data and study design reveal that no firm conclusions can be made on the basis of this work. Conclusion: No firm conclusions on screening method can be drawn due to fundamental limitations and confounding factors in this retrospective work‐based study. Recommendations for further studies are made, controlling for confounding factors. |
