The ectocervix is lined mainly by mature squamous epithelium; the endocervical canal is lined by glandular epithelium. Their meeting point is the squamocolumnar junction (SCJ). As the cervix matures and remodels, exposed columnar epithelium undergoes squamous metaplasia; the area between the original and current SCJ is the transformation zone (TZ).

The TZ matters because this metaplastic interface is where most HPV-associated squamous precancers arise. A brush must sample the ectocervix and the endocervical/TZ component appropriate to the cervix being examined.

The slides show the practical sequence:

1. Confirm identity, indication, previous results and relevant history; label the vial/request correctly.
2. Position the speculum and fully expose the cervix under good light.
3. Inspect before sampling. A friable, ulcerated, irregular or exophytic lesion goes to urgent diagnostic assessment/biopsy.
4. Place the cervical broom centrally so its longer fibres enter the os and its shorter fibres contact the ectocervix.
5. Rotate and transfer the entire cellular sample into the preservative vial according to the device manufacturer's instructions; the slide's exact turn/rinsing counts are device-specific, not universal rules.

Liquid-based cytology (LBC) disperses the sample into a standardised thin area. Compared with a conventional smear, it reduces obscuring blood/mucus and permits reflex HPV or other validated tests from the residual sample. It does not rescue a poorly positioned brush or a missed lesion.

Common causes in the slide images are:

• too few squamous cells;
• air-drying or thick-spread artefact in a conventional smear;
• heavy blood or neutrophilic inflammation obscuring epithelial cells;
• treatment effect or severe atrophy that prevents reliable interpretation; and
• specimen/identity or processing problems.

Repeat an unsatisfactory test according to the reported reason and local pathway. Treat a genuine symptomatic infection when indicated; do not give antibiotics solely to make a smear readable. A short course of vaginal oestrogen may help selected postmenopausal patients with marked atrophy after contraindications and preferences are considered, but it is not an automatic response to every unsatisfactory sample.

The lecture diagram should be read from left to right:

• LSIL/CIN1: atypical proliferating cells are mainly confined to the lower third; maturation persists above.
• HSIL/CIN2: atypia and disordered maturation extend roughly into the lower two-thirds.
• HSIL/CIN3: near-full-thickness atypia with little surface maturation.
• Microinvasion/invasion: atypical cells breach the basement membrane and enter stroma; this is a histological, not merely cytological, diagnosis.

Modern pathology commonly uses a two-tier LSIL/HSIL framework, with p16 immunohistochemistry used in selected equivocal lesions—not as a substitute for morphology.

Bethesda glandular abnormalities include:

• atypical endocervical, endometrial or glandular cells;
• atypical glandular/endocervical cells, favour neoplasia;
• endocervical adenocarcinoma in situ (AIS); and
• adenocarcinoma.

The lecture's cytology–biopsy pairs illustrate two key lessons:

1. Cytological atypia can reflect a benign mimic, such as microglandular hyperplasia.
2. True AIS may coexist with squamous HSIL and can extend discontinuously up the endocervical canal, making a satisfactory excisional specimen important.

AGC can signal cervical, endometrial or occasionally extrauterine pathology. It therefore cannot be managed as “just another mildly abnormal smear.”

The slide pathway contains reversible and irreversible-looking arrows for a reason:

Normal cervix ⇄ HPV infection ⇄ precancer → invasive cancer
                   clearance       regression

• Acquisition of HPV is common.
• Persistence of a carcinogenic HPV type is the crucial risk state.
• HPV16 and HPV18 confer particularly high risk, but validated assays test a broader high-risk panel.
• HPV testing detects infection/risk earlier than cytology detects abnormal cells; its greater sensitivity comes with lower specificity in younger populations where transient infection is common.

• Cytology: detects abnormal cervical cells.
• Primary high-risk HPV testing: detects carcinogenic HPV DNA or mRNA; a positive result requires triage, not automatic treatment.
• Co-testing: HPV plus cytology from a clinician-collected cervical sample.
• Visual inspection with acetic acid (VIA): a resource-dependent population approach, not interchangeable with formal colposcopy.
• Biomarker triage: validated p16/Ki-67 dual stain or other locally approved strategies may increase specificity among HPV-positive patients.

Only a clinically validated assay used for its approved specimen and purpose should guide management. Research genotyping platforms, methylation assays, microRNA and HPV E6/E7 tests shown in the deck are not all routine screening tests.

The imaging-system diagram is a workflow rather than an autonomous diagnosis:

sample collection → LBC preparation → automated slide scanning/field selection → trained human review and sign-out

Automation can prioritise suspicious fields in the “needle-in-a-haystack” search, but laboratory accreditation, quality controls, validated performance and expert review remain essential.

The 2026 HKCOG addendum accepts a validated self-collected vaginal sample for HPV testing as an alternative, while preferring clinician-collected cervical specimens ^[5]. Important limits:

• vaginal self-samples are for HPV testing, not cervical cytology;
• reflex cytology or p16/Ki-67 cannot be performed on a vaginal self-sample because it lacks a direct cervical-cell sample;
• HPV16/18 positivity leads to colposcopy; other high-risk HPV positivity requires a clinician-collected cervical specimen for triage; and
• two inadequate/inconclusive results should lead to clinician collection.

Routine screening is often deferred because pregnancy-related cervical change and contact bleeding can complicate sampling, but a never-screened patient may be offered screening after individual assessment. An abnormal result is not ignored: high-grade cytology is evaluated in pregnancy to exclude invasion, while endocervical curettage is contraindicated and treatment of precancer is usually deferred postpartum ^[6].

The public-health slides contrast:

• opportunistic screening: testing only when someone happens to attend care; and
• organised screening: defined target population, consented registry, invitations/recall, standardised reporting, laboratory and colposcopy quality assurance, documented referral and active follow-up of abnormal results.

The Hong Kong data in the deck are programme statistics, not the prevalence of abnormality in all local women. They also show the central challenge: those least likely to attend may carry the greatest preventable risk.

1. Is there a symptom or visible lesion? Use a diagnostic cancer pathway, not routine screening recall.
2. Was the sample satisfactory? If not, repeat/resolve the adequacy problem promptly.
3. Is the result high-grade or glandular? ASC-H, HSIL, AGC, AIS or suspected carcinoma generally needs colposcopic/diagnostic assessment.
4. If HPV-positive, what genotype and triage result? HPV16/18 carries higher risk; other types usually undergo reflex cytology/validated triage.
5. What is the history? A minimally abnormal result after previous negative HPV testing may carry a different risk from the same result after treatment or persistent positivity.

Most CIN1 represents productive HPV infection and regresses. Observation with HPV-based testing/co-testing is preferred. Treatment may be considered for a large/persistent lesion or when reliable follow-up cannot be achieved, but only after the cervix has been adequately assessed and invasion excluded ^[6].

• CIN3: treatment is recommended outside exceptional circumstances.
• CIN2: treatment is usual, but carefully selected patients prioritising future pregnancy may undergo specialist observation when the SCJ is visible, endocervical sampling is reassuring and adherence is reliable.
• Excision is generally preferred when invasion, glandular disease, a type 3 TZ or cytology–histology discordance is a concern because it provides a specimen.
• Ablation destroys tissue and is suitable only when eligibility criteria are met and invasion/glandular disease are not suspected.

Cryotherapy: the probe must fully cover an eligible ectocervical lesion; the expanding white ice ball should extend beyond the lesion. Because no specimen remains, it is inappropriate when the lesion extends into the canal, is too large, the TZ is not fully seen, or cancer/glandular disease is possible.

LLETZ/LEEP sequence shown in the slides:

1. delineate the TZ/lesion;
2. pass an electrified wire loop through the transformation zone, ideally producing an intact, orientable specimen;
3. retrieve the specimen for histology and margin assessment; and
4. secure haemostasis, commonly with ball diathermy and/or haemostatic solution.

Cone biopsy: removes a deeper cone including endocervical canal. It is useful for AIS, suspected microinvasion, discordant high-grade results or disease extending beyond colposcopic view. The wider/deeper excision shown in the diagram is not “better” by default: excision depth should balance oncological adequacy against bleeding, stenosis and later preterm-birth risk.

HPV persistence predicts residual/recurrent CIN2+ better than margin status alone. Under HKCOG 2024, HPV testing or co-testing is performed at 6 months and then annually until two consecutive normal results, followed by 3-yearly HPV-based surveillance for 25 years, continuing beyond age 65 when necessary ^[6].

Complications to counsel about include bleeding, infection, cervical stenosis and an excision-depth-related increase in adverse obstetric outcomes. Hysterectomy is not first-line treatment for cytological HSIL or uncomplicated CIN alone.