Cell preparation methods and criteria for sample adequacy: IAC task force summary

Issues: Cell Preparation Methods. Standardized fixation and optimal staining. Sampling of cervix, sampling error, homogenization of sample, subsampling. Assessment of liquid- based preparations: efficacy and economic impact. Training and transitional procedures before full implementation of new technologies. Criteria for Sample Adequacy. Clinican responsibility for collecting and providing representative sample to laboratory. Collection instruments, number of slides. Cellular content of samples: evidence of transformation zone (TZ) sampling, number of squamous cells present, obscuring factors. Screening issues. Consensus Position: The conventional cervical smear remains the standard method of cervical cancer screening but has limitations in individual test sensitivity and specificity. Sample takers should: (1) receive appropriate training in sample collection, (2) be held responsible for providing the laboratory with appropriate samples, and (3) have their performance monitored. The instruments used for sampling should collect cells from both the ectocervix and endovervix; optimally, TZ sampling, represented by the presence of endocervical or squamous metaplastic cells, should be identifiable in samples other than atrophic specimens. The adequacy of a specimen (as judged microscopically) does not guarantee that it is representative of the cervix. Each cytology report should include a comment on cellular content/adequacy of the specimen. Liquid-based preparations may overcome many of the inherent problems with the conventional cervical smear. Ongoing issues: We need further data on the cost- effectiveness of making two slides from cervical specimens and/or using two samplers rather than a single one. Do we have enough information to make recommendations as to the appropriate type of sampler to be used in particular situations, such as routine screening? What is the best method of screening for/detecting endocervical glandular neoplasia? How are such terms as unsatisfactory and inadequate defined in cervical cytology classifications other than the Bethesda System? What number and types of epithelial cells should be present (visualized) in a cervical smear or liquid-based preparation for it to be considered adequate? Do we need to have evidence of TZ sampling in specimens taken during the follow-up period after treatment of squamous intraepithelial lesion or after detection of endocervical glandular neoplasia? What criteria for obscuring factors, such as blood and inflammation, should be used in assessing adequacy? Cost-benefit analyses of utilizing liquid-based preparations are needed. Should we inform women about the technical details of the test methods available or chosen by the laboratory? Are women in a position to decide which method is the most appropriate to assess their cervical scrape sample? We need to obtain more information about the properties of proprietary liquid fixative/transport media with respect to inactivation of viral pathogens, tuberculosis and other bacterial pathogens and suitability for immunobiologic and molecular tests, etc. We need to obtain more information on the use of stoichiometric stains and the limitations of Papanicolaou stain for image analysis systems. The use of liquid-based preparation for nongynecologic cytopathology and ancillary tests must be considered, including criteria for adequacy. We need to obtain more information on the time required for and best methods of training experienced cytotechnologists to become competent at assessing liquid-based cervical preparations.