An anoscopy is a procedure that examines the lining of the anal canal to help diagnose anal conditions. Anoscopies can help doctors diagnose anal cancer, anal melanoma and benign conditions, such as anal dysplasia, hemorrhoids, fissures and fistulas.

As a colon and rectal surgeon, I perform about 500 anoscopies each year. Here, I’ll answer common questions about anoscopies.

Why would I need an anoscopy?   

You may get an anoscopy if you have symptoms such as pain or bleeding in or near the anus. We usually perform an anoscopy after a digital rectal exam.

During a high-resolution anoscopy, a diluted vinegar solution and a small microscope called a colposcope are used to examine the lining of the anal canal. It differs from a regular anoscopy because the use of a colposcope allows for greater magnification of suspicious areas. Additionally, the solution is reactive and causes abnormal cells to change color. This makes it easier for your doctor to see them.

If your doctor suspects you have cancer, they may take a tissue sample to biopsy during a high-resolution anoscopy. The biopsy can confirm whether the cells are cancerous.

Anoscopies can be used to guide anal cancer treatment

Anoscopies can be more than diagnostic. I may perform an anoscopy if you’ve already been diagnosed with anal cancer because I’m looking for features of the tumor that go beyond what a pathologist sees under a microscope. I want to know if the tumor is:

• ulcerated
• bleeding
• obstructing
• tender
• extending down to the anal canal or in the upper portion of the anus going into the rectum
• affecting the prostate or vaginal wall

I can use this information to help guide your anal cancer treatment. Anoscopies can also be used to monitor how the cancer responds to treatment or catch the cancer if it recurs.