Anoscopy Technique

Updated: Feb 01, 2016
  • Author: Fazia Mir, MD; Chief Editor: Vikram Kate, MBBS, MS, PhD, FACS, FACG, FRCS, FRCS(Edin), FRCS(Glasg), FIMSA, MAMS, MASCRS  more...
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Technique

Anoscopy

Before performing an anoscopy, visually inspect the area, then perform a digital rectal examination (DRE) to investigate for bleeding or an obvious mass. A DRE can also help to localize pain prior to the procedure.

In some cases, it may be beneficial to clear the rectum of stool. An enema may also be administered in cases of obstipation to help clear the rectal vault prior to the procedure.

When using an anoscope with an obturator, ensure that the obturator of the anoscope is completely inserted.

Generously lubricate the anoscope with standard lubricating jelly or lidocaine jelly. Introduce the anoscope gently, and advance it slowly with a slight side-to-side twisting motion while the patient bears down. If resistance due to contraction of the external anal sphincter is significant, constant pressure on the anoscope eventually fatigues the muscles and permits insertion.

Maintain pressure over the obturator with the thumb during insertion to keep the obturator from slipping out. To avoid pinching the anal mucosa, completely remove the anoscope, and reinsert the device if the obturator slips or falls out during insertion. Some anoscope models have small tabs at the operator end of the device. These tabs should be aligned along the rostral to caudal axis of the patient to allow complete insertion of the device.

Once the anoscope is completely inserted, remove the obturator.

As the anoscope is slowly withdrawn, the anal mucosa can be visualized over the entire circumference of the canal. Any debris or blood can be swabbed for analysis, if desired. As the instrument is withdrawn at the anal verge, spasm of the external sphincter may lead to rapid expulsion. Firm counterpressure prevents expulsion. Reinsertion may be required for adequate visualization of the anal verge.

High-resolution anoscopy

During high-resolution anoscopy, a microscope similar to a colposcope is used to magnify the view. A 3% acetic acid solution is applied and left in contact with the perianal skin and mucosa for 2 minutes, after which Lugol iodine solution is applied. Anal intraepithelial neoplasia (AIN) lesions usually acquire a whitish colour when in contact with acetic acid and and will not take Lugol; these properties allow them to be identified and biopsied. It must be kept in mind, however, that high-resolution anoscopy is operator-dependent and requires substantial expertise. [11]

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Complications

Anoscopy is a relatively safe procedure. The most common complication is minor irritation of the local mucosa, which can lead to some bleeding. To avoid contamination, do not reuse multiple-use anoscopes without proper sterilization. Dispose of single-use devices after use.

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