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Transformation zone sampling rate used as a performance indicator for cervical liquid-based cytology sample-takers



C. A. Faraker, Cytology Department, Conquest Hospital, East Sussex Healthcare NHS Trust, St Leonards-on-Sea; UK

Tel.: +44 1424 758023; Fax: +44 1424 758121;




To investigate the sampling performance of individual cervical cytology practitioners using the transformation zone sampling rate (TZSR) as a performance indicator and to assess the impact of dedicated on site training for those identified with a low TZSR.


The TZSR was calculated for all practitioners submitting ThinPrep® cervical cytology specimens to the Conquest laboratory between January 2010 and November 2011. After excluding those with less than 30 qualifying samples the 10th percentile of the TZSR was calculated. Practitioners with a TZSR below the 10th percentile were visited by a specialist cervical cytology screening facilitator after which the TZSR of these practitioners was closely monitored.


After exclusions there were 175 practitioners who had collected 24 358 qualifying liquid-based cytology (LBC) samples. The average TZSR was 70% (range 12–96%). The 10th percentile was 44%; 18 scored below the 10th percentile. Failure to apply sufficient pressure when sampling was identified as the most common reason for a low TZSR. In some cases there was suspicion that the cervix was not always adequately visualized. Continuous monitoring after assessment identified improvement in the TZSRs of 13/18 practitioners.


Identification of practitioners with low TZSRs compared with their peers allows these individuals to be selected for personalized observation and training by a specialist in cervical cytology which can lead to an improvement in TZSR. As previous studies show a significant correlation between the TZSR and the detection rate of cytological abnormality it is useful to investigate low TZSRs.