Comparison of Conventional Pap Smear and Liquid-Based Cytology in the detection of Cervical Intraepithelial Neoplasia and Cervical Cancer

To compare the performance of conventional Pap smear and liquid-based cytology (LBC) in the detection of cervical intraepithelial neoplasia (CIN) and cervical cancer using colposcopic-guided biopsies as the gold standard.

All women between 21 and 65 years of age were included and screened using both the conventional method and LBC. All screen positive patients further underwent colposcopy-directed biopsies. 10% of screen negative were included as controls. Sensitivity and specificity of both the methods were calculated and compared.

For low-grade cytology (ASCUS and higher grade) and low-grade histopathology (CIN1 and higher grade), conventional Pap smear had a higher specificity of 85.8% versus 73% of LBC. LBC had higher sensitivity of 100% versus 75% of conventional Pap smear. However, when high-grade cytology (ASC-H and higher grade) and high-grade histopathology (CIN2 and higher grade) were compared, LBC had better performance with a sensitivity of 100% versus 14.2% for the conventional method and accuracy of 96.6% versus 91.1%. Another advantage of LBC was in the reduction of number of unsatisfactory smears for evaluation. There was no unsatisfactory smear on LBC as compared to the conventional method which had 14% unsatisfactory smears.

Thus, for detection of high-grade lesions which are at increased risk of progression to cancer, LBC fares better in comparison with the conventional method. It has a better sensitivity, accuracy and fewer number of unsatisfactory smears.