100% rapid rescreening for quality assurance in a quality control program in a public health cytologic laboratory

Abstract

Objective To verify the efficacy of the quality control (QC) program in a cytologic laboratoiy with a rapid rescreening (PR) protocol.Study Design RR, according to the Turret RR method, of all samples initially screened as negative at the Laboratory of Cytology, Adolfo Lutz Institute, was performed. The slides were reviewed for 60 seconds. Suspect smears were fully checked by 2 reviewers to determine the final diagnoses. A total of 2,954 sequential cytologic results were considered in this study. Of the 2,954, 2,568 (86.9%) were considered initially negative according to our internal QC, and these cases underwent PR. Also, 10% were randomly selected from these negative cases for full reviewing. The internal QC in our laboratory includes review of cases selected according to clinical and cytomorphologic criteria..Results Among the 2,954 total cases, QC detected 386 (13%) atypias with final diagnoses reported according to The Bethesda, System 2001 as follows: 82 (2.18%) low grade squamous intraepithelial lesions (LSILs), 35 (1.18%) high grade squamous intraepithelial lesions (HSILs), 2 (0.06%) squamous cell carcinomas, 105 (3.5%) atypical cells of undetermined significance (ASCUS), 4 (0.12%) atypical endocervical cells (AECs) and 158 (5.3%) unsatisfactoiy samples. RR of 2,568 smears initially considered negative selected 194 (7.5%) slides. Of the 194, 146 (75.3%) were negative, 28 (14.4%) ASC-US, 5 (2.6%) AEC, 1 (0.5%) LSIL and 14 (7.2%) unsatisfactory. Full review of a 10% randomfraction of the 2,568 cases interpreted as negative did not detect lesions but did detect 5 (1.95%) unsatisfactory samples.Conclusion Internal QC used in our laboratory based on clinical and cytomorphologic criteria to select cases for review proved to be an efficient method of detecting HSIL and cervical cancer. The consensus basis of this program strongly limits the false positive and false negative rates and also provides subjects with continuing education. One hundred percent RR is more efficient than 10% full reviewing in detecting cervical abnormalities.