Comparative Evaluation of PAP Smear and Visual Inspection of Acetic Acid (VIA) in Cervical Cancer Screening Program in Lady Willingdon Hospital, Lahore

Abstract

Objective:  To compare the performance of Pap smear with visual inspection of cervix after spraying 5% acetic acid as an alternative cervical cancer screening modality in a low resource setup.

Design:  Comparative study.

Place and Duration of Study:  A pilot study was conducted on the first 100 women presenting from 1st Nov-31st Jan 2010 at gynaecological clinics, Lady Willingdon Hospital, affiliated with King Edward Medical University, Lahore, Pakistan.

Materials and Methods:  During the gynaecological speculum examination a Pap smear was taken and then 5% acetic acid was sprayed on the cervix using a spray bottle. The observations were noted as VIA positive or negative according to aceto-white changes. Similarly cytology result was graded as CIN1, 2 and 3. Those women who showed positive test result with either VIA or Pap smear or both tests were further subjected to colposcopy directed biopsy. The histology of cervical biopsy was taken as gold standard to compare the performance of VIA and cytology. Estimation of sensitivity, specificity and pre-dictive values were calculated by using standard statistical formulae.

Results:  Out of 100 subjects, 85 were negative with both screening techniques. Twenty four were positive with VIA while Pap smear was positive in 12 subjects. Histological diagnosis of CIN/cancer was made in 16 out of the total 26 patients who underwent biopsy. The sensitivity of VIA was 93% and of Pap smear was 83%. Corresponding specificities were 90% and 97%. VIA was more sensitive than Pap smear which was statistically significant (P value < .05). The PPV of VIA was 62.5% versus 83% for Pap smear which is statistically significant (P value < 0.001) The NPV of VIA was 98% versus 97% for cytology. There was no significant difference between the negative predictive values (NPV) of both tests (P value equals 1). Overall, VIA demonstrated an accuracy of 90% as compared to 96% for cytology.

Conclusion:  These results indicate that VIA is more sensitive as compared to Pap smear. The detection rate of early lesions of cervix using VIA is comparable to Pap smear in validity and usefulness. In developing countries VIA is an effective method to achieve fairly accurate and moderately reproducible results in detecting cervical cancer precursors.

Key Words:  Cervical cancer screening, Visual Inspection with acetic acid, Pap smear.