Cervical screening
Exam Tips
- Screening is for asymptomatic prevention, not a rule-out test for symptomatic cancer.
- Primary hrHPV testing comes first; cytology is triage when hrHPV is detected.
- If the cervix looks suspicious for malignancy, do urgent suspected-cancer referral rather than routine screening sample.
- Key sample quality point: collect from the entire transformation zone; if two cervices are present, sample both.
- Know deferral situations: menstruation, pregnancy, and <12 weeks postpartum or post-miscarriage/termination.
- See Figure: transformation zone/squamocolumnar junction location to explain why sampling technique matters.
Definition
Cervical screening is a population-based preventive programme for people with a cervix aged 25-64 years in the UK, designed to reduce cervical cancer incidence and mortality by identifying high-risk HPV infection and pre-invasive epithelial abnormalities before invasive cancer develops. It is not a diagnostic test for existing cancer; instead, it uses primary hrHPV testing with reflex cytology and colposcopy pathways to risk-stratify and treat precancerous disease.
Pathophysiology
Most cervical squamous and glandular neoplasia arises at the transformation zone (squamocolumnar junction), where metaplastic epithelium is vulnerable to persistent oncogenic HPV infection (especially types 16 and 18). Viral oncoproteins (notably E6 and E7) promote cell-cycle dysregulation via p53 and Rb pathway interference, driving progression from HPV infection to CIN/CGIN and, over years, invasive carcinoma in a minority of untreated cases. Primary hrHPV screening has high negative predictive value, so a negative result predicts very low short-term risk and supports longer recall intervals; cytology and colposcopy are then used to identify those with clinically meaningful lesions. See Figure: transformation zone anatomy and CIN progression (standard gynaecology pathology diagram).
Risk Factors
- Persistent high-risk HPV infection (especially HPV 16/18)
- Smoking (increases persistence and progression risk)
- Immunosuppression (e. g. HIV, post-transplant immunosuppressants, long-term systemic steroids)
- Early sexual debut and multiple sexual partners (higher HPV exposure probability)
- Previous CIN, CGIN/SMILE, or prior cervical cancer treatment
- Non-attendance at screening invitations
- No HPV vaccination
- Coexisting sexually transmitted infection and cervical inflammation
Clinical Features
Symptoms
- Usually asymptomatic in routine screening attendees
- Possible anxiety or distress after hrHPV-positive/abnormal result notification
- If symptomatic (not a routine-screen scenario): post-coital bleeding, intermenstrual bleeding, persistent vaginal discharge, or pelvic pain should prompt diagnostic assessment
Signs
- Normal cervix on speculum examination in many screened individuals
- Contact bleeding can occur during sampling and may be benign
- Suspicious cervix (friable/ulcerative/exophytic lesion) requires urgent suspected-cancer referral rather than routine sample
Investigations
Management
Lifestyle Modifications
- Provide clear pre-test counselling and obtain informed choice/consent; discuss benefits, limits, and possible harms (false negatives, overdiagnosis, anxiety, discomfort)
- Encourage attendance at scheduled recall and robust follow-up of non-attendance via fail-safe systems
- Delay sampling during menstruation, pregnancy, <12 weeks postpartum, or <12 weeks after miscarriage/termination unless clinically indicated
- If vaginal discharge/pelvic infection is present, treat first and rebook screening
- Promote smoking cessation and HPV vaccination uptake as cancer-prevention measures
- Use trauma-informed, inclusive communication for transgender and non-binary people with a cervix; arrange manual invitations where national call/recall cannot auto-invite
Pharmacological Treatment
Treatment of intercurrent genital infection before repeat sampling
- Metronidazole 400 mg orally twice daily for 7 days (e. g. bacterial vaginosis pathway)
- Pelvic inflammatory disease outpatient regimen: Ceftriaxone 1 g IM single dose plus Doxycycline 100 mg orally twice daily for 14 days plus Metronidazole 400 mg orally twice daily for 14 days
No drug treats hrHPV itself in screening practice; pharmacotherapy is for coexisting infection. Check allergy history (especially beta-lactams), pregnancy status (avoid doxycycline in pregnancy), alcohol interaction warnings with metronidazole, and antimicrobial-stewardship/local resistance guidance.
Surgical / Interventional
- Colposcopy-directed biopsy for abnormal screening results
- Excisional treatment of high-grade disease (e. g. LLETZ/large loop excision of transformation zone)
- Ablative/excisional management of selected CIN lesions in colposcopy services
- Cervical dilatation in selected severe cervical stenosis to allow adequate assessment/sampling
- Urgent 2-week suspected-cancer gynaecology referral if cervix appears malignant (do not take routine screening sample first)
Complications
- False-negative screening result with delayed diagnosis
- Interval development of CIN/cancer between scheduled recalls
- Overdiagnosis/overtreatment of lesions that might regress
- Psychological morbidity (anxiety, stigma, relationship stress) after hrHPV-positive result
- Pain, vasovagal episodes, bleeding, embarrassment, and reduced future screening uptake
- Procedural complications from treatment (e. g. bleeding, cervical stenosis; potential future obstetric impact after excisional treatment)
Prognosis
At a population level, organised cervical screening substantially improves outcomes: it prevents many cancers and has markedly reduced cervical cancer mortality in the UK. Individual prognosis is excellent when precancerous lesions are detected and treated early; prognosis worsens with non-attendance, persistent hrHPV infection, immunosuppression, and delayed investigation of red-flag symptoms.
Sources & References
🏥BMJ Best Practice(1)
✅NICE Guidelines(1)
- Cervical screening[overview]