Visual inspection with acetic acid for cervical-cancer screening: Test qualities in a primary-care setting

Background. Naked-eye visual inspection of the cervix with acetic-acid wash (VIA), or cervicoscopy, is an alternative to cytology in screening for cervical cancer in poorly resourced locations. We tested the sensitivity, specificity, and predictive value of VIA done by nurse-midwives in a less-developed country. Methods. Women were screened by six trained nurse-midwives in a two-phase, cross-sectional study at 15 primary-care clinics in Zimbabwe. VIA and Pap smears were done concurrently, and their sensitivity and specificity compared. Colposcopy, with biopsy as indicated, was used as the reference test to allow a direct comparison of the test unaffected by verification bias. Findings. 10,934 women were screened. In phase II, 2148 (97.5%) of the 2203 participants for whom there was a screening result also had a reference test result. Also in phase II, VIA was more sensitive but less specific than cytology. Sensitivity (95% CI) was 76.7% (70.3-82.3) for VIA and 44.3% (37.3-51.4) for cytology. Specificity was 64.1% (61.9-66.2) for VIA and 90.6% (89.2-91.9) for cytology. Interpretation. The high sensitivity of VIA shows that the test could be valuable in detection of precancerous lesions of the cervix. However, there are costs to the patient and system costs associated with high numbers of false-positive results, so attention should be given to improving the specificity of VIA.