A CASE-CONTROL STUDY OF TRUE-POSITIVE VERSUS FALSE-NEGATIVE CERVICAL SMEARS IN WOMEN WITH CERVICAL INTRAEPITHELIAL NEOPLASIA (CIN) III

Cervical smears (n = 150) from five departments showing high-grade dys karyosis were examined by three cytologists. All the smears came from patients with biopsy-proven CIN III. One hundred had been correctly re ported (true positives) but 50 had originally been reported as negativ e and had been found to be positive only on review (false negatives). There were significant differences between the two sets in the charact eristics of the dyskaryotic cell population. The false-negative smears tended to have fewer than 200 dyskaryotic cells. The nuclei of the dy skaryotic cells tended to have fine rather than coarse nuclear chromat in. A smear with fewer than 50 dyskaryotic cells is 26 times more like ly to be reported as negative than one with more than 200 dyskaryotic cells. The results suggest that there is a type of severely dyskaryoti c smear that is inherently likely to be missed on routine screening. ( C) 1998 Blackwell Science Ltd.