“Sip volume” as a quality indicator in liquid-based cervical cytology

Abstract

Introduction of nonmicroscopic cervical screening techniques creates the potential for liquid-based cytology specimens to be sent for human papillomavirus (HPV) testing, automated screening, or other assays prior to microscopic quality assessment. It was hypothesized that the volumes required to prepare ThinPreps ("sip volumes") represent indicators of specimen quality. A stratified random sample of 505 enrollment ThinPreps were assessed in the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study (ALTS) to evaluate associations between sip volume and slide cellularity, cellular distribution, and clinical outcomes. Masked assessments included counting cells and qualitative evaluations. Sip volumes were highest among women aged 18-19 or > or =35 years (P = .01), higher during the secretory menstrual phase (P < .0001), and lower among women with a history of Chlamydia infection (P = .04). Low cellularity was associated with Atypical squamous cells-cannot exclude high-grade squamous intra-epithelial lesion (ASC-H) interpretations at the clinical centers (P = .04). Sip volumes were related to cellularity (P < .0001) and cellular distribution (P < .0001). Sip volumes < or =2.0 mL were associated with lower cellularity and both low and high sip volumes yielded less homogeneous cell deposition. However, sip volume was unrelated to the overall performance of cytology and HPV testing. Extremely low sip volumes are associated with hypocellular ThinPreps, and very low and high sip volumes more often show uneven cellular distribution. Although results of cytology and HPV testing in ALTS were generally unrelated to sip volume, results with other protocols or assays may vary, suggesting that microscopic assessment of specimens with extreme sip volumes prior to nonmicroscopic testing may be useful.