Comparison of Visual Inspection with acetic acid and Pap smear in cervical cancer screening at a tertiary care hospital

Objective: To determine the accuracy of visual inspection with acetic acid in comparison with Pap smear against colposcopic directed biopsy, for detection of pre-cancerous lesion. Methods: The comparative cross-sectional study was conducted at the Maternal and Child Health Centre (MCHC), Pakistan Institute of Medical Sciences (PIMS), Islamabad, from January to December 2010. Every married women with age range 19 to 51 years underwent conventional cytology and visual inspection with 5% acetic acid. Distinct acetowhite areas were taken as positive, while cervical intra-epithelial neoplasia on cytology was labelled as Pap smear positive. Colposcopic directed biopsy was taken as the gold standard. SPSS 13 was used for statistical analysis. Results: Of 519 subjects, 70(13.4%) were screened positive and 29(5.6%) were biopsy positive for cervical intraepithelial neoplasia. Of these, 26(37.1 %) were positive on visual inspection; 14 (20 %) on cytology; and 30 (42.8%) on combined test. The sensitivity of visual inspection was 78.5% vs 61.1% for Pap smear (p 0.001). The specificity of visual inspection was 99.3% vs 99.4% for cytology (p 0.1). Significantly higher sensitivity and specificity was found for the combined test than either of the two alone; 93.1% and 99.1% respectively (p 0.001). The positive predictive value of visual inspection vs pap was 84.6% vs 78.5% (p 0.001) and negative predictive value was 98.6% vs 96.5% (p 0.1). Both values of combined test were significantly higher than either of the two tests alone (p 0.01). Conclusion: Visual inspection with acetic acid has significantly higher sensitivity than Pap smear and may replace pap smear as a primary screening tool for universal screening. Combined test with higher predictive accuracy may be used for opportunistic screening.