Cervical (Pap) smear. New directions.

This article reports the historic background leading to the introduction of cervical smears as a tool in the detection of precancerous changes in the uterine cervix. The false-negative error rate in the primary screening process is discussed and illustrated by data recently compiled from this laboratory. Rescreening of approximately 25% of cervical smears yielded an error screening rate of approximately 5% of precancerous lesions and cancer of the uterine cervix. The total false-negative screening error rate was much higher but was unknown and should be determined by additional studies. The reasons for the false-negative screening errors are discussed. Some of the proposed remedies, particularly screening of the entire population for human papillomavirus infection, are judged to be unacceptable because of the high prevalence of this virus in well women and because the biologic events linking the presence of viral DNA with the development of precancerous lesions are unknown. Screening assistance with the help of a newly developed interactive machine, combining image analysis with a neural net was promising as a tool in quality control.