Anoscopy

Contraindications

Caution is needed in patients with recent anal surgery or known anal fissure.

Applications

Diagnosis of problems associated with perianal and anal discomfort and other symptoms.

Equipment necessary

• Anoscope

• Gloves

• Cotton swabs (large tip)

• Bright light source

• Lubricant

Set-up

This procedure is performed with the patient in the left lateral position and draped. It is very helpful if an assistant is available. As well, a topical anesthetic, applied 30 minutes beforehand, can reduce discomfort for the patient and increase the ease of the procedure. It is also important to discuss the procedure with the patient beforehand, as the patient is likely to feel anxious.

Evidence

Although there is little literature on anoscopy (and, arguably, the detection of gross lesions is valuable regardless of evidence), our search revealed 2 studies suggesting effectiveness of anoscopy for human papillomavirus screening using anal Pap smears. The first paper reviewed the current evidence for detection of anal squamous intraepithelial lesions and the treatment options.¹ Cytology screening yielded a 47% to 90% sensitivity rate and a 16% to 92% specificity rate for anal squamous intraepithelial lesions, although it is more sensitive in patients with HIV. The authors recommend screening HIV-positive men who have sex with men (MSM) yearly, as well as every second year for HIV-negative MSM. The second article discussed the sensitivity of anal cytology as well and found a sensitivity of 70% and a positive predictive value of 97% for histology of any grade of lesion.² It also found that cytology is more sensitive in MSM than in heterosexual men.

Diagnostic confirmation

Patients with recalcitrant or severe lesions should be referred to specialists for endoscopic confirmation with or without biopsy. Bleeding in higher-risk individuals (including those older than 50 years of age) should not be assumed to originate from hemorrhoids, even when hemorrhoids can be seen.