Relation between quality of cervical smears and probability of abnormal results

European guidelines for quality assurance in cervical cancer screening: recommendations for collecting samples for conventional and liquid-based cytology*

The current paper presents an annex in the second edition of the European Guidelines for Quality Assurance in Cervical Cancer Screening. It provides guidance on how to make a satisfactory conventional Pap smear or a liquid-based cytology (LBC) sample. Practitioners taking samples for cytology should first explain to the woman the purpose, the procedure and how the result will be communicated. Three sampling methods are considered as acceptable for preparing conventional Pap smears: (i) the cervical broom; (ii) the combination of a spatula and an endocervical brush; and (iii) the extended tip spatula. Smear takers should take care to sample the entire circumference of the transformation zone, to quickly spread the cellular material over a glass slide, and to fix the preparation within a few seconds to avoid drying artefacts. According to local guidelines, one of these three methods may be preferred. Sampling with a cotton tip applicator is inappropriate. Similar procedures should be followed for sampling cells for LBC, but only plastic devices may be used. The collected cells should be quickly transferred into a vial with fixative liquid according to the instructions of the manufacturer of the LBC system. Subsequently, the slide or vial and the completed request form are sent to the laboratory for cytological interpretation.

Does feedback improve the quality of cervical smears? A randomized controlled trial

In a randomized controlled trial three methods of feedback of increasing intensity, directed at 183 doctors taking cervical smears, were compared with respect to their effects on the sampling quality of smears. Overall, feedback was found to have no influence on quality criteria in the crude data analysis. However, a significantly larger decrease in the percentage of smears lacking endocervical cells was found in the groups receiving monthly overviews of their results with peer comparison, when compared with the groups not receiving this type of feedback (odds ratio 0.75). Moreover, feedback appeared to have a clear effect on the presence of endocervical cells among doctors submitting a substantial number of smears in the intervention period, as opposed to those who submitted fewer smears. A positive correlation was also observed between the increase in the group mean of the proportions of smears containing pathological cells and the intensity of the feedback. However, this increase did not reach statistical significance. This study suggests that monthly feedback with peer comparison may have a positive relationship with some aspects of quality improvement in cervical screening.

Interobserver variation in the assessment of the sampling quality of cervical smears

In order to assess the interobserver variation among cytological assistants in evaluating the sampling quality of cervical smears, all four laboratory assistants from one cytological department examined the same set of 71 smears. They assessed the presence of endocervical cells, the quality of fixation, the number of cells and the undesirable presence of clumps of cells. The interobserver agreement, uncorrected for chance, varied from 73 to 93% for the presence of endocervical cells and from 86 to 100% for the three other criteria. For the presence of endocervical cells, the kappa values, a measure for the interobserver agreement corrected for chance, varied from 42 to 84%. This is a reasonable outcome. For the three other criteria many kappa values were zero or uncalculable. The interobserver agreement in evaluating the sampling quality of cervical smears is reasonable to good, but not perfect. Prudence in the interpretation of quality data is warranted.