GUIDELINES FOR ANAL CYTOLOGY - TO MAKE CYTOLOGICAL DIAGNOSIS AND FOLLOW-UP MUCH MORE RELIABLE

Anal intraepithelial neoplasia is a difficult diagnostic and managemen t problem, particularly when it occurs in women with synchronous or me tachronous genital intraepithelial neoplasia. Diagnosis and follow up by colposcopy is too specialized for widespread use, and although anal cytology has been used before it has been thought of as too inconsist ent for practical application. This study standardized collection of s pecimens and investigated interobserver variation. The aim of the stud y was to determine whether observers could reliably distinguish high g rade anal intraepithelial neoplasia from other conditions. Standardize d collection of anal preparations was achieved in the host centre. A m eeting of experienced cytopathologists was convened to agree guideline s for anal cytology. These guidelines were sent to the panel of six ob servers who were subsequently circulated with 30 cytopathological prep arations in random order and asked to report them all. The results wer e collected and processed centrally. Four individuals were in complete agreement about those preparations which were inadequate for reportin g, but two others had a lower threshold for rejecting preparations as inadequate. There was agreement between the observers in over 95% of c ases in distinguishing high grade intraepithelial neoplasia from other cytological conditions. Kappa values range from 0.66 to 1.00. This st udy demonstrates that the provision of guidelines for the interpretati on of anal cytopathological preparations can result in a high degree o f interobserver agreement about the clinically important distinction b etween high grade anal intraepithelial neoplasia and other conditions. Anal cytology is a more useful technique for diagnosis and follow up of 'at risk' individuals than has previously been suggested, and shoul d be utilized more widely in this group of patients.