Chapter 10: Cervical cancer screening using visualization techniques

There is a resurgence of interest in the use of visual techniques to identify cervical intraepithelial neoplasia (CIN). These visual techniques can be divided into two general categories. One is the simple visual screening method, such as direct visual inspection (DVI), during which the cervix is visualized with either the naked eye or a low-power magnification device after the application of a solution of 3% to 5% acetic acid that is used as a chemical contrast agent to highlight regions of CIN. DVI has been evaluated in a number of large clinical trials and is considered by some to be a possible alternative to cervical cytology for primary cervical cancer screening in low-resource settings. The advantages of DVI compared with cervical cytology for these settings are that it is inexpensive, it does not require a laboratory infrastructure, and it provides an immediate result, allowing the use of "screen and treat" protocols. The major disadvantage of DVI is that it is relatively nonspecific and that its sensitivity is low compared with testing for human papillomavirus. The other category of visual techniques includes devices that use electro-optical sensors and light of specific wavelengths produced by lasers or specialized light sources to identify and localize regions of CIN on the cervix. Although these "high-technology" devices are not yet in routine clinical use, several groups and companies have such devices in clinical trials.