Negative smears in women developing invasive cervical cancer.

Fifty-six cervical smears originally classified as Pap. I, from women in whom cervical cancer of stage I to IV was detected within 4 to 5 years after the cytological check, were re-examined in order to estimate the screening error and sampling failure. At the review, 35 smears were classified as Pap. II to V. The incidence of changed classification of the smears obtained from population screening was 70% and that of the smears taken at private specialists or at hospitals was about 50%. The influence of sampling failure on the evaluation of the smears classified as Pap. II should be considered. On 14 slides, correctly interpreted as negative, there were no columnar cells present, a fact that may indicate inefficient sampling of cells from the squamo-columnar junction.