Updated: Nov 21, 2023
  • Author: Fazia Mir, MD; Chief Editor: Vikram Kate, MBBS, MS, PhD, FACS, FACG, FRCS, FRCS(Edin), FRCS(Glasg), FFST(Ed), FIMSA, MAMS, MASCRS  more...
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Patients may present in the outpatient or emergency department (ED) setting with various anorectal conditions. [1]  A high degree of professionalism is especially warranted in these cases because of the nature of the examination.

As part of the initial evaluation, obtain a complete history of the present illness, perform a physical examination of the abdomen, and perform a visual inspection of the anus and perineum. The next step, if necessary, is a digital rectal examination (DRE).

If the data obtained from the external visualization and DRE are insufficient to make a definitive diagnosis, anoscopy may be performed to visualize the anus, anal canal, and internal sphincter. [2, 3, 4]



Indications for anoscopy include the following:

  • To visually investigate anorectal conditions for which a DRE does not provide sufficient diagnostic information
  • To obtain information on conditions such as internal hemorrhoids or disruption and other pathology of the rectal mucosa, or to examine for an anorectal mass or foreign body in the anal canal
  • To obtain samples for cytology [5] as a screening method for anal squamous lesions, [6, 7, 8, 9, 10, 11] particularly in high-risk patients with HIV infection [12, 13, 14, 15]

High-resolution anoscopy (HRA) can be used for the purposes of surveillance after treatment of anal squamous cell carcinoma with chemoradiation or excision. [16, 17]



Anoscopy should not be performed on an imperforate anus. Caution should be exercised on patients who have recently undergone anal or rectal surgery.

HRA is a preferred screening method in the diagnosis of anal intraepithelial neoplasia (AIN) [18, 19, 6] ; however, despite its sensitivity in identifying patients with AIN, its routine use is not justified, and conventional anoscopy is carried out for the diagnosis of other conditions.


Technical Considerations


The anal canal is the terminal part of the lower gastrointestinal (GI) tract (ie, the large intestine or colon). It lies between the anal verge (anal orifice or anus) in the perineum below and the rectum above. The pigmented, keratinized perianal skin of the buttocks (around the anal verge) has skin appendages (eg, hair, sweat glands, and sebaceous glands); it may be contrasted with the anal canal skin above the anal verge, which is also pigmented and keratinized but does not have skin appendages.

For more information about the relevant anatomy, see Anal Canal Anatomy.