Visual inspection of the cervix after application of 5% Lugolís iodine (VILI) has been evaluated as a screening test for cervical cancer. However, the VILI test is not widely recommended, because of the cost and the difficulties in procuring the chemicals required to prepare the Lugolís iodine solution. Moreover, the efficacy of screening with VILI in reducing mortality from cervical cancer has not been established.
Application of Lugolís iodine may help to better delineate VIA-positive lesions and guide treatment. The strong colour contrast between the normal cervical epithelium, which stains with Lugolís iodine, and the abnormal epithelium, which does not take up Lugolís iodine, helps to demarcate the outer margin of the lesion before treatment of cervical neoplasias by ablative or excisional methods in a screen-and-treat setting. Iodine stains the glycogen-containing normal epithelium to dark brown, while the neoplastic epithelium, in which the abnormally dividing cells do not produce glycogen, remains unstained. The normal epithelium appears dark mahogany brown, whereas the diseased epithelium is visible as areas appearing bright yellow or mustard yellow. The sharp contrast between the abnormal epithelium and the normal epithelium enables much better delineation of the abnormal transformation zone that needs to be treated.
- Iodine uptake areas are always considered normal.
- Iodine non-uptake areas are visible in several non-neoplastic conditions, such as atrophic epithelium, inflammation, squamous metaplasia, and healing and regenerating epithelium.
- An iodine-negative area due to CIN or invasive cancer is usually uniformly bright yellow and is always located within the transformation zone.