Anoscopy explained: Purpose, process and results
June 19, 2025
Medically Reviewed | Last reviewed by on June 19, 2025
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.
What is the difference between anoscopy and colonoscopy?
Anoscopy and colonoscopy evaluate different parts of the gastrointestinal tract.
A colonoscopy uses a camera called a colonoscope to examine the lining of the entire colon, or large intestine. This procedure helps diagnose colorectal cancer or identify precancerous polyps.
An anoscopy uses a smaller instrument and examines the anal canal. It is a shorter procedure that requires less preparation than a colonoscopy. You won¡¯t be given anesthesia for an anoscopy.
What is the difference between anoscopy and proctoscopy?
A proctoscopy uses an instrument called a proctoscope, which is longer than an anoscope. The extra length of the proctoscope allows doctors to examine the inside of both the anal canal and the rectum.
Do you have to prepare for an anoscopy?
There is not much you need to do to prepare for an anoscopy.
While stool does not hang around in the anus, there may be stool present in the wall of the rectum. Stool may make it harder for a doctor to see during the anoscopy. So, we typically ask patients to have an enema the morning of their anoscopy or when they get to the office. This will cleanse the lower bowel of any stool before the procedure.
Your doctor will give you specific instructions to follow before your procedure.
Can an anoscopy be done in a doctor¡¯s office?
An anoscopy is a simple diagnostic procedure that can be done in a clinic or doctor¡¯s office. It is typically performed by a surgeon or a colon and rectal specialist.
What happens during an anoscopy??
During an anoscopy, your doctor will insert a lubricated tube called an anoscope into your anus. Your doctor may wear a headlamp light that allows them to see inside the anal canal.
If you¡¯re getting a high-resolution anoscopy, your doctor will place a cotton swab with a diluted vinegar solution in your anus. If abnormal cells are present, the solution will help make them more visible. Your doctor will then remove the cotton swab and use a colposcope to examine the abnormal cells under high magnification. Your doctor may take a small sample of the abnormal cell tissue to biopsy.
Is an anoscopy painful?
Most people tolerate the procedure well and do not need anesthesia or sedation. ?If the area is already sensitive or causing you pain, your doctor may use a topical numbing agent before inserting the anoscope to make the anoscopy more comfortable. If you¡¯re experiencing any pain, that can help your doctor understand the severity and cause of your condition.
The anus is a collapsed organ. So, the anus becomes dilated when something is coming out of it, such as passage of stool, or a finger or scope is going into it. When your anus is dilated, you get the sensation that you¡¯re pooping. So, I always tell patients, an anoscopy will feel similar to a bowel movement. You don¡¯t need to feel anxious about it.
How long does an anoscopy take?
A typical anoscopy takes about 3 minutes. A high-resolution anoscopy takes about 8 minutes, and if I¡¯m collecting tissue to biopsy, it takes about 10 minutes.?
What will my recovery be like?
You can go home the same day after your anoscopy. You may have a little discomfort or?bleeding in your anal area, especially if you¡¯ve had a biopsy. These symptoms should go away after a few days.
Your doctor will provide you with detailed aftercare instructions. Be sure to follow the instructions, and let your doctor know if you have any worsening symptoms.
When will I get my results?
It usually takes about week for your doctor to get the biopsy results. Your doctor will share the results with you and discuss the next steps, which might include additional testing or treatment.
I often treat any lesions in the office during the time of the anoscopy. So, when the pathology reports come back, patients usually don¡¯t need additional treatment.
, is a colon and rectal surgeon at MD Anderson.
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