Characteristics of false-negative ThinPrep cervical smears in women with high-grade squamous intraepithelial lesions

KM Leung, KK Lam, PY Tse, Gary PS Yeoh, KW Chan
Diagnostix Pathology Laboratories Ltd, Canossa Hospital, 1 Old Peak Road, Hong Kong

OBJECTIVE. To examine the cellular characteristics and other possible factors affecting the correct prediction of ThinPrep cervical smears from patients with high-grade squamous intraepithelial lesions.

DESIGN. Retrospective study.

SETTING. Private anatomical pathology service, Hong Kong.

PATIENTS. Patients (n=98) with biopsy-confirmed high-grade squamous intraepithelial lesion of the uterine cervix encountered between 2004 and 2006.

MAIN OUTCOME MEASURES. Correct prediction of the cervical ThinPrep Papanicolaou tests.

RESULTS. There were no significant differences in age, hormonal status, degree of inflammation, and the presence or absence of endocervical/metaplastic cells between the true-positive and false-negative groups. There was a significant difference in the number of abnormal cells present and the screening time between the two groups. Approximately 79% (34/43) false-negative smears had 100 or less abnormal cells, while only 11% (5/45) true-positive smears had 100 or less abnormal cells (P<0.001). The true-positive smears were also more likely to contain koilocytic cells and abnormal cells with hyperchromatic nuclei.

CONCLUSIONS. The number of abnormal cells present, the presence or absence of koilocytic cells, and the presence or absence of abnormal cells with nuclear hyperchromasia appeared to be independent factors affecting the correct prediction of smears from patients with high-grade squamous intraepithelial lesions.

Hong Kong Med J 2008;14:292-5

Key words: Cervix uteri; Papillomavirus infections; Uterine cervical neoplasms; Vaginal smears