BACKGROUND - Although the Bethesda System provides concise, specific descriptions for classifying cervical cytology, its usefulness has been questioned in the United States and abroad. The author attempted to evaluate the impact of the Bethesda System on cervical screening and subsequent management decisions.
METHODS - A MedLine search provided statistical information for comparison of screening procedures and results before and since introduction of the Bethesda System. The effect of the Bethesda System was evaluated by specimen adequacy, inclusion of human papillomavirus changes in the squamous intraepithelial lesion (SIL) category, and effect on the number of abnormal Pap smears.
RESULTS - By 1992, 85% of cytology laboratories were using Bethesda system terminology. Diagnosis and treatment of patients with atypical squamous cells of undetermined significance (ASCUS) and low grade squamous intraepithelial lesions were reviewed. In women with ASCUS smears, follow-up studies showed that between 5% and 13% actually had high grade cervical lesions. For patients with a cytologic diagnosis of low grade SIL, one study found an 18.6% incidence of high grade lesions demonstrated by colposcopically directed cervical biopsy. An estimated 2% increase has occurred in the number of women with abnormal Pap smear results who require additional evaluation costing more than $1 billion.
CONCLUSIONS - The Bethesda System has improved the quality of Pap smear diagnosis in the United States, but the number of women with abnormal Pap smear results has increased. Although this increase is partly due to the terminology of the Bethesda System, other factors play a role. Whether this has improved cancer prevention is unknown.