An advantage of cervical cytology over screening methods such as visual screening is that even though quality assurance and quality control programmes can be developed for both, the availability of archival glass slides facilities such programmes. Various definitions for quality control and quality assurance are used by laboratories.
In general, quality control can be thought of in terms of the actual assessments that are done to ensure high quality and quality assurance can be thought of in terms of the entire process of maintaining minimum standards and continually striving for excellence. Quality assurance should be a coordinated effort that is designed to control, detect and prevent the occurrence of errors and hopefully to improve patient care. In general, there are three stages to the process of quality control (Bozzo, 1991):
- Setting standards for what one wishes to control and defining the benchmarks;
- Developing a mechanism for assessing what one wishes to control;
- Defining the response to be taken when deficiencies are identified.
For cervical cytology screening, quality assurance programmes can include a number of types of activity and should take into account country and location-specific needs. What may be considered acceptable or even mandatory in one setting may serve simply to limit the availability of screening in other settings. It is critical, however, that any cervical cytology laboratory or programme has an established quality assurance programme. In general, it is preferable for cytology services to be centralized as much as possible, to facilitate quality assurance. The use of computerized data collection systems that can integrate cytological findings, histological findings and follow-up information is highly desirable (Miller et al., 2000).
Preanalytic Quality Control
Preanalytic quality control measures include the records that laboratories should maintain relating to specimen receipt, preparation of specimens, staining of specimens and upkeep of equipment and microscopes, as well as records of personnel and their training and education.