This page was reviewed under our medical and editorial policy by
Chukwuemeka Obiora, MD, Surgical Oncologist
This page was updated on March 8, 2024.
An anoscopy is a medical procedure used to diagnose and monitor health conditions of the rectum and anus, including cancer. A thin tube, called an anoscope, is used during the procedure.
This guide will help patients and their families learn the basic facts about anoscopy, including:
Anoscopy is often performed in a doctor’s office or an outpatient facility. During the procedure, a small, thin tube (anoscope) is inserted into the rectum. The anoscope tube is hollow and firm, about 3 to 4 inches in length, with a light on the end. The tube is covered in a lubricating gel for a more comfortable insertion.
The anoscope allows doctors to view the rectal and anal linings at the end of the body’s digestive tract. If suspicious areas are identified, the doctor may perform a biopsy to remove tissue samples and have them tested by a pathologist for the presence of cancer.
An anoscopy may be recommended if patients have the following symptoms:
The procedure may be used to diagnose:
In some instances, a doctor may recommend a high-resolution anoscopy. This procedure differs from an anoscopy in that it uses a magnifying instrument called a colposcope to look for abnormal cells.
During a high-resolution anoscopy, the doctor uses an anoscope to insert a swab covered in a liquid (acetic acid) into the anal cavity. This liquid turns abnormal cells white, making them visible to the care team when seen through the colposcope. If abnormal cells are found, they may be biopsied.
Anoscopy and colonoscopy are both commonly used medical procedures to diagnose health conditions in the digestive tract, but they’re used to examine different parts.
While an anoscope examines the anal canal to look for health conditions such as anal cancer, a colonoscopy allows doctors to look inside the large intestine (colon). A colonoscopy may be used for colorectal cancer screening and is more invasive than an anoscopy.
Before an anoscopy, patients are given preparation instructions specific to their situation. Generally, patients should try to empty both their bladder and bowel before the procedure begins.
This procedure is usually performed in an outpatient setting or a doctor’s office. The doctor may use a local anesthetic beforehand to help numb the area.
During an anoscopy exam, patients lie on their side so that the doctor may first perform a digital rectal exam (DRE). This involves the doctor inserting a lubricated and gloved finger into the anus to feel for bumps or abnormalities in the rectum.
Then, the anoscope is inserted with lubrication a few inches into the anus. If abnormal cells are found, a biopsy may be taken by gently brushing with a swab or other tool so that further tests may be done.
The procedure may feel uncomfortable, but it should not feel painful. Patients should tell their doctor if they’re experiencing pain during the procedure.
An anoscopy is a safe and well-tolerated procedure with few risks. However, complications are possible with any medical procedure.
The risks associated with an anoscopy include:
Lubricant is used during the anoscopy to help reduce the risks above.
In rare cases, infection is also possible.
After an anoscopy, the care team gives patients guidelines about what to expect, but in most cases, patients go home shortly after the procedure.
If a biopsy is performed, bleeding for a short time after the procedure is common. However, if patients notice any unexplained changes after the anoscopy, they should contact their doctor.
After an anoscopy, the care team provides information on when the results will be ready. If a biopsy is taken, results may be available in two to 10 days. If cancer is detected, next steps may include additional testing or a personalized treatment plan.