Colposcopic differentiation of abnormalities arising in the transformation zone.

When metaplastic cervical epithelium is exposed to the factors responsible for neoplasia, the transformation zone becomes atypical. These changes, visible as acetowhite epithelium, altered vascular patterns, and irregular surface contour, are easily recognized through the colposcope in most patients. It is possible to grade the changes to determine the severity of the abnormality and so, in consultation with the patient, decide on the best management course. However, there will always be lesions where colposcopy is indeterminate, and biopsy of such lesions is mandatory. Combined colposcopy and histology are still the mainstays of clinical management. As yet, more refined investigations, such as HPV-subtype determination, have not demonstrated any advantage for these patients.