Interobserver concordance in the assessment of features used for the diagnosis of cervical atypical squamous cells and squamous intraepithelial lesions (ASC-US, ASC-H, LSIL and HSIL).

OBJECTIVES

Given the well-known poor reproducibility of cervical cytology diagnosis, especially for atypical squamous cells of undetermined significance (ASC-US) and low-grade squamous intraepithelial lesion (LSIL), this study surveyed reproducibility in the assessment of individual cytomorphological features.

METHODS

One hundred and fifty cells or groups of cells, with a variety of morphological appearances, including normal cells, high-grade squamous intraepithelial lesion (HSIL), LSIL, ASC-US and ASC cannot exclude HSIL (ASC-H), were precisely marked on 150 different liquid-based cytological preparations. They were analysed by 17 observers who assessed 17 cytological features including nuclear features (chromatin texture, nuclear outline, nuclear shape, etc.), cytoplasmic features (cell shape, cytoplasmic staining, cytoplasmic clearing, etc.) and group characteristics (nuclear polarity, cellular density, etc.). A total of 43,350 data scores were collected in a database using a web-based survey. Kendall's W and relative entropy indexes were utilized to compute concordance indexes of respectively ordinal and nominal variables.

RESULTS

Nuclear features have significantly lower reproducibility (0.46) compared with other cytological features (0.59). The feature with least agreement is assessment of chromatin texture. A small but significant difference in concordance was found between two subsets of observers with different levels of experience.

CONCLUSION

Most previous studies assessing reproducibility of cytological diagnoses show, at best, moderate reproducibility among observers. This study focused on agreement regarding the presence of constituent morphological features used to recognize dyskaryosis and various grades of squamous intraepithelial lesions. A map of reproducibility indexes is presented that highlights, for daily practice or teaching, the robustness of features used for cytological assessment, recognizing that diagnosis is always based on a combination of features.