- Position the patient
- Lithotomy position is most common; left lateral (Sims) or prone jackknife also acceptable
- Provide adequate draping and exposure of the perianal region
- Inspect the perianal skin
- Look for warts, lesions, fissures, ulcers, or scarring
- Note any external haemorrhoids, tags, or signs of chronic trauma
- Insert the anoscope
- Lubricate lightly with water
- Insert a transparent anoscope into the anal canal
- Once inserted, remove the obturator to allow clear view of the canal
- Aim to visualise the transformation zone, which is the target for inspection
- Use the colposcope for magnified inspection
- Bring the colposcope into position about 15–20 cm from the anal verge
- Adjust light and magnification as needed
- Apply 3–5% acetic acid
- Soak a cotton swab or gauze and apply to the anal canal mucosa
- Wait ~1–2 minutes for acetowhitening effect to develop
- Abnormal areas (AIN) will appear as white, thickened, raised, or irregular mucosa
- Apply Lugol’s iodine (optional, used in some protocols)
- Normal glycogenated epithelium stains brown
- Dysplastic or neoplastic epithelium remains unstained or yellow
- Identify suspicious lesions
- Look for changes in colour, surface contour, vascular pattern, or epithelial thickening
- Use standard colposcopic descriptors (mosaicism, punctuation, acetowhite changes)
- Biopsy abnormal areas
- Use small biopsy forceps via the anoscope
- Aim for the worst-looking area if multiple lesions are present
- Control bleeding with direct pressure, silver nitrate, or topical adrenaline if needed