Colposcopy and treatment of CIN/CGIN

A 31-year-old is referred because her cervical screening test is HPV-positive with a high-grade squamous intraepithelial lesion on cytology. You are the colposcopist. The decision you make next — biopsy only, see-and-treat, or observe — sets her oncologic course and her future obstetric risk. This is one of the few encounters where overtreatment is measurable in premature babies. This topic is that encounter, written from the published evidence.^[2][3]

Overview and definition

Colposcopy is a magnified, illuminated examination of the cervix (and vagina and vulva) after the application of acetic acid. Its purpose is to localise premalignant change in the transformation zone, biopsy it, and direct treatment. The whole subject turns on one fact that the published reviews state plainly: most cervical cancers develop in the transformation zone, the area of squamous metaplasia at the squamocolumnar junction (SCJ).^[13][17]

Cervical intraepithelial neoplasia (CIN) describes the atypical squamous changes that arise in the transformation zone, graded by the depth of epithelial involvement — CIN 1, CIN 2 and CIN 3, from mild to severe. Local treatment is by ablation or excision, and the choice depends on the grade and extent of the disease.^[14]

Cytology is reported using the Bethesda system, which has standardised reporting terminology and provided the basis for risk-based management strategies.^[7]

References18ShowHide

1. [1]Perkins RB, Guido RS, Castle PE, Chelmow D, Einstein MH, Garcia F, et al. 2019 ASCCP Risk-Based Management Consensus Guidelines: Updates Through 2023 J Low Genit Tract Dis, 2024.PMID 38117563
2. [2]Kyrgiou M, Koliopoulos G, Martin-Hirsch P, Arbyn M, Prendiville W, Paraskevaidis E Obstetric outcomes after conservative treatment for intraepithelial or early invasive cervical lesions: systematic review and meta-analysis Lancet, 2006.PMID 16473126
3. [3]Athanasiou A, Veroniki AA, Efthimiou O, Kalliala I, Naci H, Bowden S, et al. Comparative effectiveness and risk of preterm birth of local treatments for cervical intraepithelial neoplasia and stage IA1 cervical cancer: a systematic review and network meta-analysis Lancet Oncol, 2022.PMID 35835138
4. [4]Mitchell MF, Tortolero-Luna G, Cook E, Whittaker L, Rhodes-Morris H, Silva E, et al. A randomized clinical trial of cryotherapy, laser vaporization, and loop electrosurgical excision for treatment of squamous intraepithelial lesions of the cervix Obstet Gynecol, 1998.PMID 9794661
5. [5]Pinder LF, Parham GP, Basu P, Muwonge R, Lucas E, Nyambe N, et al. Thermal ablation versus cryotherapy or loop excision to treat women positive for cervical precancer on visual inspection with acetic acid test: pilot phase of a randomised controlled trial Lancet Oncol, 2020.PMID 31734069
6. [6]Basu P, Mwanahamuntu M, Pinder LF, et al. A portable thermal ablation device for cervical cancer prevention in a screen-and-treat setting: a randomized, noninferiority trial Nat Med, 2024.PMID 38918630
7. [7]Nayar R, Wilbur DC The Pap Test and Bethesda 2014: "The reports of my demise have been greatly exaggerated" J Low Genit Tract Dis, 2015.PMID 25943863
8. [8]Bell SG, Peng K, Kobernik EK, Miller ME, Lieberman R, Saunders NA, et al. Fertility and Pregnancy Outcomes After Conservative Management of Adenocarcinoma In Situ of the Cervix J Low Genit Tract Dis, 2021.PMID 34369435
9. [9]Garland SM, Skinner SR, Brotherton JM Adolescent and young adult HPV vaccination in Australia: achievements and challenges Prev Med, 2011.PMID 21962468
10. [10]Apter D, Wheeler CM, Paavonen J, Castellsagué X, Garland SM, Skinner SR, et al. Efficacy of human papillomavirus 16 and 18 (HPV-16/18) AS04-adjuvanted vaccine against cervical infection and precancer in young women: final event-driven analysis of the randomized, double-blind PATRICIA trial Clin Vaccine Immunol, 2015.PMID 25651922
11. [11]Checchi M, Mesher D, Mohammed H, Soldan K Declines in anogenital warts diagnoses since the change in 2012 to use the quadrivalent HPV vaccine in England: data to end 2017 Sex Transm Infect, 2019.PMID 30723186
12. [12]Papoutsis D, Williams J, Underwood M, Parry-Smith W Healing pattern of the cervical stroma following cold coagulation treatment for cervical intraepithelial neoplasia: A case report Oncol Lett, 2022.PMID 35126723
13. [13]Boldeanu L, Assani MZ, Boldeanu MV, Siloși I, Manolea MM, Văduva CC, et al. Cervical Cancer in the Era of HPV: Translating Molecular Mechanisms into Preventive Public Health Action Int J Mol Sci, 2025.PMID 40943384
14. [14]Martin-Hirsch PP, Paraskevaidis E, Bryant A, Dickinson HO Surgery for cervical intraepithelial neoplasia Cochrane Database Syst Rev, 2013.PMID 24302546
15. [15]Chen C, Xu Y, Huang W, Du Y, Hu C Natural history of histologically confirmed high-grade cervical intraepithelial neoplasia during pregnancy: meta-analysis BMJ Open, 2021.PMID 34417214
16. [16]Nikolopoulos M, Athanasias P, Godfrey MAL, Nikolopoulos K, Maheshwari MK Cervical glandular neoplasia referrals and the diagnosis of adenocarcinoma in situ: Correlating cytology, colposcopy findings, and clinical outcomes Cytopathology, 2021.PMID 34181788
17. [17]Effah K, Tekpor E, Wormenor CM, Essel NOM Transformation zone types: a call for review of the IFCPC terminology to embrace practice in low-resource settings Ecancermedicalscience, 2023.PMID 38414959
18. [18]Behrens AS, Dietl AK, Adler W, Geppert C, Hartmann A, Knöll A, et al. Evaluation of endocervical curettage (ECC) in colposcopy for detecting cervical intraepithelial lesions Arch Gynecol Obstet, 2024.PMID 39472340