P‐4 TRANSFORMATION ZONE COMPONENT IN LIQUID BASED CERVICAL CYTOLOGY

Abstract

Introduction: Quality assurance guidelines for the UK cervical screening programme recommend that more than 80% of cervical samples from women aged 20–50 years should contain adequate numbers of Transformation zone (TZ) cells i.e. 10 or more endocervical or squamous metaplastic cells. This study was conducted to assess the frequency of TZ component in Liquid Based Cytology (LBC) both for ThinPrep (TP) and SurePath (SP) LBC. Also to assess the degree to which this is recorded by individual screeners and to determine the percentage of samples with evidence of TZ component for the different smear takers.Method: All LBC cervical specimens received at a tertiary cytology centre in the year 2004 from women aged 20–50 years were included in the study. Evidence of TZ sampling was recorded as: TP = TZ present (10 or more TZ cells)TA = TZ absentTS = TZ scanty (less than 10 TZ cells)TN = atrophic smears, TZ cells not recognisableResults: The total number of LBC cervical cases was 7445. TP = 4300 (mostly primary care) and SP = 3145 (mostly colposcopy). Overall TZ sampling rate in LBC was 82%. TP = 77.17%; SP = 88.24%. When scanty TZ was included, the standard was met for both systems (TP = 93.7%; SP = 88.24%). Presence/absence of TZ component was recorded in 6370 cases (85.1%); range 0%–97.79%. 56.7% of smear takers achieved the minimum standard for TZ sampling.Discussion: The percentage of ThinPrep samples containing adequate TZ cells was 77.17% compared to SurePath, which was 88.24%. This may be due to different patient populations i.e. primary care versus colposcopy. Screeners recorded TZ sampling in approximately 85% of samples. 56.7% of smear takers met the standard for TZ sampling.