Low-Grade Pap Smears Containing Occasional High-Grade Cells as a Predictor of High-Grade Dysplasia

Objectives: This study compared clinical outcomes associated with Pap smear reports of atypical squamous cells cannot exclude HSIL (ASC-H) and those associated with "low-grade smears containing occasional cells suggestive of HSIL" (LSIL-H). In Alberta, women with ASC-H are referred for colposcopy, and women with LSIL are managed with follow-up Pap smears. LSIL-H is not included in the Bethesda classification and has not been characterized in terms of cytological features, reporting, management, and clinical course. Methods: All ASC-H (n = 153) and LSIL-H (n = 189) Pap smears recorded in the regional laboratory information system between December 2000 and December 2001 were identified. All available histology for each associated patient over the subsequent two-year period was reviewed to determine if a high-grade histological lesion was ever confirmed in a biopsy, loop electrosurgical excision procedure (LEEP), or hysterectomy specimen. Results: A high-grade squamous intraepithelial lesion was identified in 48% of the ASC-H group and 40% of the LSIL-H group (P = 0.136). Most of the HSIL histopathology was identified on the first colposcopic visit, suggesting that high-grade dysplasia may have been present at the time of the original Pap smear. Conclusions: Pap smears reporting ASC-H and LSIL-H predict a high-grade squamous intraepithelial lesion with similar accuracy. Since approximately 40% of patients with an LSIL-H Pap smear have either concurrent or subsequent high-grade cervical pathology, we also recommend immediate referral for colposcopy in this group of patients.