Assessment of the Validity and Reproducibility of the Pap Smear in Mexico: Necessity of a Paradigm Shift

Abstract

An assessment was performed of the quality of Pap readings in 19 cytology laboratories (CLs) in Mexico from the Cervical Cancer Screening Program. Nine CLs were affiliated with the Health Ministry (SSA), and ten were affiliated with the Mexican Social Security Institute (IMSS). Two sets of 200 cervical cytology specimens were prepared, one set for each institution. Fourteen percent of the specimens were positive and six were inappropriate for diagnosis (3%). All cervical cytology specimens were processed in the cytopathology laboratory at the General Hospital of Mexico, and histopathology was available for each positive case. Thirty percent of the SSA reading centers had a sensitivity of at least 80%; however, not one of the ten IMSS laboratories evaluated reached this figure. Some reading centers had a sensitivity <65%, meaning that nearly half of the specimens with a cytology consistent with cervical neoplasm were not identified. Given these results, it is a priority to effect a paradigm shift combining various screening tests to improve adherence to standards and enhanced cost-effectiveness of the early detection of cervicouterine cancer (CC) in Mexico.