High Resolution Anoscopy

What is Anal Dysplasia?

Anal Dysplasia is abnormal cells (or a lesion) in the lining (skin) of the anal canal. It can be low-grade (mild) or high-grade (moderate to severe). Some low-grade lesions may progress (get worse) to high-grade lesions. High-grade lesions are very common. High-grade lesions can progress to cancer. About 1/1,000 of high-grade lesions per year will progress to cancer.

Anal dysplasia is caused by the human papillomavirus (HPV).


What is HPV?

HPV is the most common sexually transmitted virus.  There are over 40 different HPV types that may infect the genital (private) area.

Learn more about HPV-related diseases.

Frequently Asked Questions (FAQs) for Anal Cancer and Anal Dysplasia

1. Who is at risk of getting anal cancer?

A risk factor is anything that affects your chance of getting a disease such as cancer. People at increased risk for anal dysplasia/cancer may have the following risk factors:

  • Having many sexual partners or having sex with a partner who has had many partners
  • Having receptive anal intercourse (anal sex)
  • Men who have sex with men (MSM)
  • HIV/AIDS infection
  • History of anal warts
  • History of other sexually transmitted infections
  • History of fissures, fistulas and hemorrhoids
  • Organ transplant recipients and other groups who have reduced immunity
  • Women, particularly those with a history of cervical or vulvar dysplasia or cancer
  • Being over 50 years old
  • Being infected with HPV
  • Smoking cigarettes

2. What happens during an evaluation for anal dysplasia and cancer?

History:  Your provider will ask you about how you are doing, your health habits, past illnesses and treatments.
-Digital Exam: An exam of the anus and rectum. Your provider inserts a lubricated, gloved finger into the anus and lower part of the rectum to feel for lumps or anything else that seems unusual.

Anal Pap test (or anal cytology): A moist swab, like a Q-Tip ® is passed into the anal canal and cells that come off on the swab are examined under a microscope. This procedure helps to check for abnormal cells in the anus. It takes about 10 seconds and causes minimal discomfort.

It takes about 2 weeks to get the Anal Pap Test results back.

Anal Pap Test Results

Benign or Normal: There are no abnormal changes in the cells and no treatment is needed. The anal Pap test should be repeated in 6 to 24 months, depending on what risk factors you have.

  • Unsatisfactory or Inadequate: The specimen collected was not adequate and your provider will likely recommend a repeat anal Pap test at your next appointment.
  • Atypical Squamous Cells of Unknown Significance (ASCUS): The cells are abnormal, but no definite diagnosis can be made. These are non-cancerous changes. It may be caused by inflammation or associated with dysplasia. High resolution anoscopy (HRA) is recommended.
  • Atypical Squamous Cells, cannot exclude High-grade lesion (ASC-H): The cells are abnormal. These are probably pre-cancerous changes. HRA is indicated.
  • Low-grade Squamous Intraepithelial Lesion (LSIL): Mild dysplasia. LSIL could mean that you have anal warts or there could be pre-cancerous areas. HRA is definitely indicated, but you might not need any treatment.
  • High-grade Squamous Intraepithelial Lesion (HSIL): Moderate to severe dysplasia. The cells in your anus show changes most likely caused by HPV infection. This is a sign that you probably have a pre-cancerous area in your anus. Again, this does not mean you have cancer.  HRA is definitely indicated, and you may be referred for treatment.
  • Squamous Carcinoma: Fortunately this is a very rare occurrence but means that the cells show severe changes that are very suspicious for a cancer. You need immediate HRA or referral to a surgeon.

HRA with Possible Biopsy:

The provider will use a plastic instrument called an anoscope and look at the anal canal with a special microscope called a colposcope. If an abnormal area is seen, then a very small piece of anal tissue may be removed (biopsy) and sent to a specialist (pathologist) to check for signs of cancer. Anyone with an abnormal anal Pap test should have an HRA with possible biopsy to examine the anal canal.  The procedure takes about 15 minutes.

3. How can I protect myself against HPV infection and anal dysplasia?

  • Practice safer sex—using condoms EVERY time you have sex—this will reduce the risk of getting HPV.
  • Have fewer sexual partners- this will decrease the chance of getting HPV.
  • Stop cigarette smoking.
  • Vaccination with the HPV vaccine, Gardasil®, approved for girls and boys between the ages of 9 and 26, can help protect against infection with HPV types 6, 11, 16 and 18 in people who are not already infected with these types.

Although anal dysplasia can be treated successfully, people with HPV are at high risk of having it come back. While important to your health, HPV therapy does not protect against anal dysplasia/cancer. It is important to follow up with regular check-ups.

Online Resources

For more information on anal cancer, please download the (PDF) brochures for Anal Dysplasia/Cancer, High Resolution Anoscopy (HRA) and Hyfrecation.

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