[Screening and follow-up for cervical cancer prevention in rural Mexico using visual inspection]

To compare the standard cervical cancer screening procedure--the Papanicolaou test or Pap smear--with detection through visual inspection using acetic acid (VIA), and visual inspection with acetic acid assisted by Aviscope (VIAM).

The study was conducted between October 1998 and December 2000, in two Mixteca regions in Oaxaca, Mexico. A field trial design was used to randomize the two regions to either of the two inspection methods. In one region 2,240 women received VIA; in the other, 2,542 women received VIAM. Women positive to visual inspection and a subsample of women with negative results were referred for colposcopy and, if necessary, cervical biopsy. Statistical data analysis consisted of descriptive statistics and comparison of groups using chi-squared tests. Diagnostic values were obtained for VIA and VIAM, using as gold standards colposcopy and biopsy.

VIAM identified a higher proportion of women with a cervical abnormality (16.3%) than VIA (3.4%), as well as normal women (58.5% vs. 53.8%).VIA identified a higher proportion of women with benign changes (41.2%) than VIAM (19.6%).VIAM had a greater sensitivity (p>0.05) but lower specificity (p<0.05) than VIA, using as gold standards colposcopy and biopsy.

The two study groups were comparable for age, parity and cytological results; however, visual inspection results were different between the groups: VIAM identified more lesions confirmed by biopsy. The diagnostic utility of VIAM and VIA was lower than expected. Training of clinical personnel in visual inspection is critical to improve the effectiveness of these screening methods.