Internal Quality Control Indicators in Cervical Smear Screening- Report From a Tertiary Care Center, India

Introduction: Quality indicators are one of the tools to monitor the Quality Control (QC) system and have revolutionised the field of laboratory medicine. Internal QC helps in identifying the non conformities in lab from the moment sample reaches the lab and till the report is being despatched. This study was performed to evaluate the internal QC indicators of cervical smears with an intent to know where we stand, identify the lacunae and to improve performance of lab services.

Aim: To evaluate the internal QC indicators of cervical smears in an effort to improve performance of lab services.

Materials and Methods: This was a retrospective cross-sectional study conducted in the year 2021. Archived reports of females >18 years of age who had undergone Papanicolaou (Pap) smears between August 2019 and August 2021 were collated from the Department of Pathology, AIIMS, Mangalagiri. Based on these reports, various internal quality indicators, including positivity rate, percentage of Atypical Squamous Cells (ASC) among satisfactory tests, percentage of ASC among abnormal tests {includes Atypical Squamous Cells of Undetermined Significance (ASCUS), ASC-H, Low-grade Squamous Intraepithelial Lesion (LSIL), High-grade Squamous Intraepithelial Lesion (HSIL), carcinoma} ASC/SIL ratio, ASCUS/SIL ratio, percentage of LSIL, percentage of HSIL, percentage of false negatives, percentage of unsatisfactory smears were calculated. Data was analysed by using the Statistical Package for the Social Sciences (SPSS, version 15.0; IBM, USA) and descriptive statistical analysis was calculated for the quality indicators.

Results: A total of 1227 Pap smear cases were analysed in two-year duration, out of which 41 cases were unsatisfactory (3.34%). The annual smear positivity rate ranged from 1.19-1.31%, ASC percentage among the abnormal tests- 40%, ASC percentage among the satisfactory tests- 0.50%, percentage of tests with LSIL- 0.08%, percentage of tests with HSIL- 0.25% and false negative rate- 0.16%. ASC/SIL ratio and ASCUS/SIL ratio were 1.50% and 1.25%, respectively.

Conclusion: The internal QC indicators obtained in the present study were lower than the recommended values by CAP/Bethesda. Thus, achieving benchmark in internal quality indicators is still far from reality as it depends on population, screened incidence of cervical lesions and expertise of sampling team and cytopathologists. Regular audit improves screening ability of the test. Thus, every lab should try to achieve the internal quality indicator goals, which will ultimately result in building a good cervical screening system.