High Resolution Anoscopy
High Resolution Anoscopy (HRA) is a diagnostic procedure which allows for examination of anal canal and perianal skin under magnification. It is performed for diagnosis and subsequent treatment of suspicious HPV caused dysplasias which may progress into cancer. HRA is performed in high risk groups for anal cancer, especially if anal cytology shows abnormal cells in the anal canal lining.
Because of the special training and the extensive infrastructure required, the number of clinicians performing HRA is quite small. HRA is available in US and in a small number of European countries and Australia. In Greece, the last four years, HRA is performed exclusively in our proctology clinic. Its technique derives from colposcopy which is performed for the identification of precancerous dysplasias in the external female genitalia. HRA is very different from colonoscopy or flexible sigmoidoscopy, neither of which can adequately examine the anus for HPV infection and dysplasias. Flat lesions, which tend to be premalignant, are not detected without acetowhitening and high magnification.
HRA is performed in outpatient basis, without any anesthesia, and lasts about 15 minutes. Significant post examination problems such as bleeding or fever are extremely rare. Before examination, a gauze soaked with dilute acetic acid (vinegar) is inserted into the anal canal for 2-4 minutes through a hollow tube (anoscope). After removal of the gauze, the anoscope is reinserted and the anal canal and perianal skin are examined under magnification looking for lesions with characteristics of HPV infection and high grade dysplasias (grey staining, mosaicism, coarse punctuation, abnormal blood vessels, etc.). Acetic acid and Lugol staining are used to make lesions more visible and help physician decide where to biopsy.
Biopsies are an essential part of the examination and should be done after careful photo-documentation for easy localization during repeat HRA for any subsequent treatment. Biopsies are performed to localize and subsequently treat premalignant changes that are susceptible to further develop into anal cancer. If biopsy results show high-grade dysplasia (HGAIN), HRA is repeated and the dysplastic lesions, correlated with previous HRA mapping and the photographic documentation, are cauterized under local anesthesia