Quality assurance/control issues. International Academy of Cytology Task Force summary. Diagnostic Cytology Towards the 21st Century: An International Expert Conference and Tutorial.

ISSUES: General definitions of quality assurance and quality control (QA/C) have existed in many forms for decades, and a new discipline guides their application to diverse industrial and recently medical processes without much fanfare. However, in the field of cervical cytology screening, the range of QA/C options has recently broadened and become controversial. With the advent of new systems of terminology, larger-scale laboratories and new technologies--plus strong governmental and legal pressures in some nations--the range of extremely difficult and sometimes expensive QA/C choices our community faces is greater than ever. CONSENSUS POSITION: At our conference, the basic definitions of QA/C posed little difficulty. Presentation of the range of methods in use today and of those based on new technologies where use is proposed or has just begun also was achieved with little or no dispute. However, there was lack of consensus on exactly how QA/C methods are to be assessed. Indeed, there was little consistency in the use of different outcome measures with which we can judge success or failure of specific QA/C options. In addition, the tension between pressure to adopt sometimes uncertain or expensive method enhancements and pressure to maintain affordability and the widest possible access for populations that most need cervical cytology screening is greater than ever. ONGOING ISSUES: More data are required that would enable assessment of QA/C options with the clearest possible understanding of cost/benefits and current or new assumptions of risk. Other task forces, such as medicolegal, cost/benefit and those devoted to new technologies, are our essential partners in meeting the challenges described above.

The false negative rate in cervical cytology. Comparison of monolayers to conventional smears.

OBJECTIVE: To compare cervical monolayers prepared by a density gradient technique to conventional smears. STUDY DESIGN: The study evaluated 2,863 patient samples. After conventional smears were prepared, the residual samples (collected in preservative fluid) were processed by the monolayer preparation system, which disaggregates the cells, removes nonclinical debris and layers the diagnostic material onto a microscopic slide. Slides were screened in Germany and the United States in masked studies. RESULTS: In the U.S. study, the false negative rate for the conventional smears was 9.4% when endocervical components were present and 16.7% when absent. The false negative rate for the monolayer preparation was 4.0% when endocervical components were present and 5.7% when absent. A comparison of the diagnostic results showed that the monolayer made possible the detection of 48 cases of low grade disease or higher that were not found on the conventional smear. The German study was independent but used the same samples. The results, although based upon the Papanicolaou classification, were similar. CONCLUSION: Cervical samples that are preserved in a liquid suspension and prepared using the density gradient monolayer technology have many advantages over conventional cervical cytologic smear preparations. The quality of cell preservation and presentation is superior. Elimination of obscuring material, homogeneity of the sample and standardized quality work together to produce preparations that can be effectively and reliably screened by cytotechnologists. These preparations should greatly enhance the reliability of machine-based screening in the future.

Preliminary evaluation of Cyto-Rich: an improved automated cytology preparation.

A new cervical cytology monolayer preparation system called Cyto-Rich was evaluated. Using samples from 557 patients, Cyto-Rich monolayers were compared to matched conventional smears. After conventional smears were prepared and spray fixed, residual exfoliated cells were transferred to preservative fluid. The cell suspensions were gently disaggregated and the epithelial component enriched with gradient centrifugal sedimentation. The batched samples were then placed on the Cyto-Rich work station where slides are automatically prepared and stained. The results demonstrate that Cyto-Rich prepared monolayers are vastly superior to the conventional smears for cell presentation. While the study showed 99% overall concordance. Cyto-Rich improved the detection of low-grade cervical intraepithelial lesions.

In vitro tolerance induction to a thymus-dependent antigen with BALB/c and C57BL/6 lymph node cells: effect of tolerogen concentration and duration of exposure.

Further studies on tolerance induction in vitro to bovine gamma globulin (BGG) in nonadherent BALB/c lymph node cells showed that it was dependent upon both the dose of tolerogen and the time of exposure. Nearly complete tolerance was achieved at a dose of 1.0 mg/ml and an incubation time of 12-18 hours. When C57BL/6 strain was used for comparison with the BALB/c strain because of its relative ease to become tolerant after in vivo injection of tolerogen, the rate of tolerance induction of its nonadherent lymph node cells was not different from that of BALB/c cells. Thus, in the absence of other host factors, the acquisition of tolerance by lymphocytes is gradual and may reflect the time required for a cell to reach a susceptible phase of the cell cycle and/or the activation of suppressor cells.