Anal dysplasia · Colposcope-guided assessment
High-resolution anoscopy (HRA), colposcope-guided assessment of anal HSIL for anal cancer prevention.
High-resolution anoscopy (HRA) uses a colposcope with acetic acid and Lugol’s iodine to identify and biopsy anal high-grade squamous intraepithelial lesions (HSIL). Follow-up test after abnormal anal cytology; the landmark ANCHOR trial showed HSIL treatment prevents anal cancer.
Why patients choose us
- 01
The right hands
We route you to a consultant working within a multi-disciplinary anal-dysplasia clinic — the person who examines you is the person who reports the findings.
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Answers on the day
Findings from the colposcope-guided assessment are usually explained immediately, with the histology report to follow.
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Independent, and free
We are paid by no clinic, so the recommendation is impartial and costs you nothing.
Key facts
What HRA is — in six lines.
The essentials of high-resolution anoscopy: what it is, when it’s used, and why it matters for anal cancer prevention.
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Definition
A colposcope-guided assessment of the anus with acetic acid and Lugol’s iodine to identify precancerous lesions.
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Follow-up after abnormal cytology
The standard next step after an abnormal anal cytology (anal smear) result.
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Targeted biopsy of HSIL
Small biopsies of high-grade squamous intraepithelial lesions confirm the diagnosis histologically.
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ANCHOR trial evidence
The landmark ANCHOR trial demonstrated that treating HSIL prevents progression to anal cancer.
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MDT anal-dysplasia clinic
Delivered within a multi-disciplinary service alongside colorectal, GUM, HIV and oncology teams.
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Complements HPV vaccination
Sits alongside HPV vaccination as part of a coordinated anal cancer prevention pathway.
The problem
An abnormal anal cytology needs the right next step.
Anal cytology detects abnormal cells; only HRA identifies where the high-grade lesion actually is, and whether it should be treated. We route you to a service equipped to do both.
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Abnormal anal cytology?
We arrange an HRA within an accredited anal-dysplasia service, with the histology-driven next step.
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Living with HIV or immunosuppressed?
We fold HRA into your existing HIV, GUM or transplant follow-up, coordinated with your team.
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Prior cervical or vulval HSIL?
Multi-site HPV disease is common — we can coordinate anal, cervical and vulval assessment together.
Preparation and journey
From referral to report — what happens, in order.
One clinician from first message to histology — often within days of your cytology result.
Phase 1 · Before your appointment
Concierge, off-stage for you
Phase 2 · On the day
~30 minutes in the clinic
Phase 3 · After
Concierge, back on
- 01
Before
Referral from anal cytology programme
Most patients are referred after an abnormal anal cytology (anal smear) result, or from HIV, GUM or transplant clinics.
- 02
Before
No specific bowel prep needed
No enemas or fasting are required. Come as you are; a light meal beforehand is fine.
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On the day
Position on the couch
You will be positioned in the left-lateral or lithotomy position, with a gown and drapes for comfort and dignity.
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On the day
Colposcope focused on the anal canal
A slim anoscope is placed, and the colposcope is focused on the anal canal and peri-anal skin.
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On the day
Acetic acid and Lugol’s iodine applied
Dilute acetic acid and Lugol’s iodine highlight areas of abnormal squamous epithelium under magnification.
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On the day
Targeted biopsies of abnormal areas
Small biopsies are taken from any suspicious lesions using fine forceps — most patients tolerate this well without anaesthetic.
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After
Discharge with report
You go home the same day with post-procedure advice; the written histology report follows in 1–2 weeks with a clear next step.
Typical end-to-end: 2–3 weeks including histology. Urgent cases: same week.
What it shows
What high-resolution anoscopy can find.
Under magnification with acetic acid and Lugol’s iodine, the anal canal and peri-anal skin reveal a specific set of findings — from low-grade HPV change to invasive cancer.
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Low-grade squamous intraepithelial lesion (LSIL)
Mild HPV-related changes that are usually monitored rather than treated.
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High-grade squamous intraepithelial lesion (HSIL)
The precancerous lesion targeted by the ANCHOR trial — the reason HRA exists.
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Anal squamous cell carcinoma
Invasive cancer occasionally identified on biopsy — triggers an urgent oncology and MDT pathway.
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Persistent HPV changes
Ongoing HPV-related epithelial changes despite prior treatment or immune recovery.
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Post-treatment surveillance findings
Assessment of residual or recurrent disease after ablation, imiquimod or excision.
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Concurrent condylomata
Anal warts frequently found alongside dysplastic change and treated in the same clinic.
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Peri-anal lesions
Extra-canal skin lesions on the peri-anal margin, examined and biopsied under the same magnification.
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Red flag: SCC on biopsy — urgent oncology / MDT pathway
An SCC result triggers immediate referral to colorectal, oncology and the anal-cancer MDT.
Treatment and next steps
What happens after HRA.
Treatment is tailored to grade, size and location — from surveillance for low-grade change to ANCHOR-validated ablation for HSIL.
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Watchful surveillance for LSIL
Low-grade lesions are usually followed with interval HRA rather than treated.
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HSIL ablation (thermal, electrocautery)
Office-based ablation of high-grade lesions — the ANCHOR-validated treatment.
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Topical imiquimod for HSIL
Immune-modulating cream used for multifocal or intra-canal HSIL where ablation is impractical.
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Excisional biopsy of large HSIL
Formal excision under local or general anaesthetic for extensive lesions.
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HPV vaccination if unvaccinated
Adjuvant nonavalent HPV vaccination for those not previously immunised.
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Peri-anal condyloma treatment
Ablation or topical treatment of visible anal warts alongside dysplasia care.
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Concurrent cervical / vulval HSIL screening
Coordinated colposcopy and vulval assessment where multi-site HPV disease is likely.
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Structured HRA follow-up
Interval-based re-examination protocols after treatment or for high-risk surveillance.
Our vetted London network
A small panel of clinics, we picked them.
Anal-dysplasia services across central London teaching hospitals and specialist clinics. Not listed publicly — introductions are made privately, once we understand your case.
Selection criteria
How we choose every clinic in our network.
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Consultants trained in high-resolution anoscopy within an accredited anal-dysplasia service
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Colposcope-based magnification with acetic acid and Lugol’s iodine as standard
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Same-visit histology sampling with a named reporting pathologist
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Onward oncology, colorectal and MDT pathway if SCC or persistent HSIL is confirmed
Safety and eligibility
A well-tolerated outpatient examination.
HRA is safe and well-tolerated. The important points are around post-biopsy care, immune status and when a finding needs escalation.
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Painless in most cases
Most patients describe the examination as pressure rather than pain; a local anaesthetic gel can be used.
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Small biopsies are routine
Targeted biopsies are taken with fine forceps — mild spotting for 24–48 hours is normal.
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No fasting or bowel prep
Eat, drink and take medication as normal on the day of the procedure.
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Immunosuppression matters
HIV status, CD4 count, transplant medication and biologics all influence the frequency of surveillance.
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Post-procedure bleeding
Light bleeding is expected; heavy bleeding or fever needs same-day medical review.
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Sexual activity
Avoid receptive anal intercourse for 1–2 weeks after biopsy to allow healing.
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HPV vaccination sits alongside
HRA does not replace HPV vaccination — the two work together as prevention.
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Pregnancy
HRA can be performed in pregnancy where clinically indicated, usually with obstetric input.
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Bring prior cytology and biopsy reports
Comparison with earlier cytology, histology and prior HRA maps sharpens the assessment.
Red flags — escalate promptly
Situations that need urgent review, not a routine slot.
- Anal squamous cell carcinoma on biopsy
- Persistent HSIL despite treatment
- Palpable anal mass on examination
- HIV with a low CD4 count
- Post-transplant / long-term immunosuppression
- Prior cervical or vulval HSIL
- Persistent HPV positivity
- Bleeding with unexplained weight loss
- Any immunosuppressed patient with new anal symptoms
Reading your report
An HRA report can look intimidating. It isn’t.
Whatever the finding, the report keeps to the same four parts.
A quiet reminder
The report is written for your doctor, not for you — and that’s normal.
If you would like us to talk you through it before your follow-up, just ask.
- 01 Header
Indication and risk factors
Your details, referral source, HIV / immune status, HPV vaccination history and prior anal cytology results.
- 02 Technique
Colposcope, acetic acid and Lugol’s
Which reagents were applied, positions examined and how many biopsies were taken.
- 03 Findings
Lesion location, grade and histology
Mapped by clock position and distance from the dentate line, with the histology grade for each biopsy.
- 04 Impression
The conclusion: read this first
Normal, LSIL, HSIL or SCC — with the concrete next step (surveillance, ablation, imiquimod or MDT).
Sources
What informs this page.
- British HIV Association (BHIVA). Guidance on the management of anal dysplasia and cancer in people living with HIV.
- International Anal Neoplasia Society (IANS). Consensus guidelines for anal cancer screening.
- Palefsky JM et al. Treatment of Anal High-Grade Squamous Intraepithelial Lesions to Prevent Anal Cancer (ANCHOR study).
- NHS Cervical Screening Programme guidance on colposcopy and anal screening pathways.
Recognised by major UK insurers
Cover depends on your policy and clinic; we confirm with your insurer before booking.
Frequently asked
Everything we get asked about HRA.
Quick answers on why HRA is done, what it feels like, and what happens if HSIL is found.
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What is high-resolution anoscopy (HRA)?
HRA is a colposcope-guided examination of the anal canal and peri-anal skin. Dilute acetic acid and Lugol’s iodine highlight abnormal squamous epithelium under magnification, so that any high-grade lesions can be targeted with a small biopsy.
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Why has my clinician recommended HRA?
Almost always because an anal cytology (anal smear) has come back abnormal, or because you are in a higher-risk group — living with HIV, on long-term immunosuppression after transplant, or with a history of cervical or vulval HSIL.
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Does HRA hurt?
Most patients describe the examination as pressure rather than pain. A local anaesthetic gel can be used and biopsies are taken with fine forceps — mild spotting for 24–48 hours afterwards is normal.
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Why does treating HSIL matter?
The ANCHOR trial showed that treating anal high-grade squamous intraepithelial lesions (HSIL) significantly reduces progression to anal squamous cell carcinoma in people living with HIV — this is the evidence that anchors modern practice.
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What treatments are used for anal HSIL?
Options include office-based thermal or electrocautery ablation, topical imiquimod, and excisional biopsy for larger lesions. The MDT chooses based on the size, distribution and location of disease.
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How often will I need follow-up?
Follow-up intervals depend on your histology, immune status and treatment. Most patients are seen every 6–12 months while on the pathway, with longer intervals once disease is stable.
Related tests
Looking for a different test?
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Anal cytology screening
The anal smear that comes before HRA in most pathways.
Learn more -
HPV cervical smear
The cervical arm of HPV screening — often coordinated with anal assessment.
Learn more -
Cervical biopsy
Colposcopy-guided biopsy of the cervix under the same magnification principle.
Learn more -
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In practice, in London
Why private high resolution anoscopy moves differently in London
With high resolution anoscopy, the London question is usually about report turnaround and the radiologist reading it — not whether the scan is available. Waiting lists on the NHS for high resolution anoscopy vary widely by borough and by how the GP letter reads. Privately in London, we can normally offer a slot inside the same week, sometimes within 48 hours if there’s a cancellation. The difference isn’t clinical quality — the consultants are frequently the same faces you’d see on the NHS — it’s the calendar.
In practice, a private high resolution anoscopy appointment in London means a named consultant, a proper hour in the room (or the equivalent on a video call), and a report you can actually read. Most of the imaging suites and endoscopy units we use sit within a mile of Harley Street or in Chelsea and Fulham, and turnaround on findings is measured in days, not weeks. For high resolution anoscopy specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.
Where a good concierge earns its keep is in the matching. There are dozens of consultants in London who see high resolution anoscopy — but not all of them are the right fit for every case. We narrow it down based on subspecialty, insurer coverage, the specific question being asked, and whether continuity into treatment matters. The right first appointment saves you from repeating yourself later.