A High Resolution Anoscopy is performed in response to certain abnormal anal Papanicolaou smear results. An anal Papanicolaou (Pap) smear cytology consists of using anal swabs to obtain a sampling of cells from the anal canal and can be used for both screening patients considered high-risk (see list above) and as follow up after anal dysplasia has been treated. Up to 45% of patients can have a false-positive test by anal pap for anal dysplasia. The results of anal pap smears can be negative (normal), atypical squamous cells of undetermined significance (ASCUS), low-grade squamous intra-epithelial lesion (LSIL) or high-grade squamous intra-epithelial lesion (HSIL).
HRA typically involves the application of temporary stains (3% acetic acid and Lugol’s iodine solution) to the anal canal followed by evaluation under high-resolution microscopy to help differentiate normal from abnormal tissue. This is very similar to colposcopy (examination of the cervix) in women who have cervical dysplasia and can be done as an office procedure. Directed biopsies and local destruction are performed for any questionable areas and to identify areas that may need further treatment. Photodynamic therapy or infra-red coagulation may be used in select patients. Similar to use in other types of skin cancers, photodynamic therapy has been described in patients with anal dysplasia since 1992. In the event there are larger areas in need of intervention, high resolution anoscopy can be done in the operating room on a larger scale than can be reasonably performed in the office setting.
When performed in the office setting, patients can expect this procedure to take between 5 to10 minutes. Mild discomfort and some bleeding for a few days following the procedure are normal.