CIN 1, CIN 2, CIN 3: how I read a cervical biopsy result
In short: CIN is not cancer. It describes changed cells within the surface layer of the cervix, found in a tissue sample taken at colposcopy. CIN 1 most often clears on its own and is observed. CIN 3 is always treated. CIN 2 sits in between: it is usually treated, but observation is acceptable for young women planning a pregnancy. Here is what the number stands for, what is known about the odds, and what follow-up looks like.
What CIN is and where the word comes from
CIN stands for cervical intraepithelial neoplasia. It is a term from the histology report: the pathologist writes it after examining, under a microscope, a piece of tissue taken by biopsy during colposcopy. Cytology — the smear — does not use it; there you see LSIL and HSIL. A smear shows single cells and tells us whether to look further; a biopsy shows the tissue as a whole, and treatment decisions are based on it.
The key word is “intraepithelial”. The changed cells lie within the surface layer and have not crossed its lower boundary, the basement membrane. While that boundary is intact, this is not cancer: such cells have no access to blood vessels and cannot spread.
The cause is almost always the same — a high-risk human papillomavirus that has persisted in the cells of the cervix. That is why I always read the biopsy result alongside the HPV test: it shows whether the infection is still there.
How CIN 1, CIN 2 and CIN 3 differ
The number tells how much of the thickness of the epithelium is taken up by changed cells, counting from the bottom.
| Result | What is seen under the microscope | Other names | What is usually done |
|---|---|---|---|
| CIN 1 | changes in the lower third of the epithelium | LSIL, mild dysplasia | observation |
| CIN 2 | up to two thirds of the thickness | HSIL, moderate dysplasia | treatment; observation possible for young women and those planning a pregnancy |
| CIN 3 | more than two thirds or the full thickness | HSIL, severe dysplasia, carcinoma in situ | treatment |
Will it clear on its own: what the numbers say
- CIN 1. Clears on its own in more than half of cases, usually within a year or two. About one case in ten goes on to CIN 3.
- CIN 2. Over two years of observation without treatment, the changes clear in half of women, persist in a third and progress in 18%. In women under 30 the picture is better: 60% clear and 11% progress.
- CIN 3. Rarely clears on its own. In a study where women with CIN 3 were not treated, about a third developed cancer within 30 years; after treatment, fewer than 1% did.
These are figures for large groups. No one can predict how the changes will behave in a particular woman, which is why “observation” does not mean “waiting”. It means colposcopy and tests on a schedule, and the schedule matters.
What happens next with each result
CIN 1 is not treated. The HPV test is repeated after a year, often together with cytology. If the result is normal, you return to routine screening, with closer checks in the first years. If CIN 1 persists for two years or longer, observation can continue; treatment is acceptable at that point but not required. A separate case is when cytology before the biopsy showed HSIL but histology found only CIN 1: that mismatch is reviewed more carefully and follow-up is scheduled sooner.
CIN 2 is treated by default. But if a pregnancy lies ahead and the risk to a future birth matters more to the woman, observation is acceptable: colposcopy and an HPV test every 6 months, for up to two years. Under the age of 25, observation is the preferred approach. If the changes have not cleared in that time, or have become CIN 3, treatment follows.
CIN 3 is always treated; observation instead of treatment is not offered. The one exception is pregnancy, covered below.
How it is treated: loop excision and conization
The changed area is removed together with the transformation zone — with a thin electrical loop (LEEP, LLETZ) or as a cone (conization). It is an outpatient procedure, most often under local anesthetic, and takes minutes. The removed tissue goes to histology again, to check that there are no deeper changes and that the margins are clear, meaning the area was removed completely.
Pregnancy after treatment is possible. The risk of preterm birth after an excision is somewhat higher than usual and depends on how much tissue was removed — which is why only as much as necessary is taken, and why observation is considered for young women with CIN 2. Be sure to tell the doctor who looks after your pregnancy about the procedure.
Before treatment I explain which procedure is needed and why, and afterwards I take care of the follow-up: HPV test, cytology and colposcopy on schedule.
After treatment: follow-up for years
Treatment removes the changed area but not always the virus, so follow-up continues for a long time. The first HPV test is at 6 months. Then once a year until three results in a row are negative. After that, every three years for at least 25 years. It sounds like a lot, but it is one short visit each time, not treatment.
CIN and pregnancy
If CIN is found during pregnancy, treatment is deferred until after delivery — as long as there is no suspicion of an invasive process. Until then the cervix is monitored with colposcopy, which is safe in pregnancy. Reassessment is done no earlier than four weeks after delivery; the changes are often smaller by then.
When not to wait for the scheduled check
- bleeding or spotting after intercourse;
- bleeding between periods or after menopause;
- discharge of an unusual color or smell that does not go away;
- pain in the lower abdomen or during intercourse that was not there before.
These symptoms more often have causes other than CIN, but they call for an examination now, not on the date set for six months from today.
How it works with me
Bring your cytology, HPV test or histology result — in any language. At colposcopy I examine the cervix under magnification and, if indicated, take a targeted biopsy from the spot that looks changed. Whether it hurts is described in detail in my article on what colposcopy feels like. The histology result is usually ready in 7 to 14 days, and we go through it together.
- colposcopy — 350 zł;
- colposcopy with a consultation — 640 zł;
- consultation — 290 zł.
I see patients in Warsaw, in the Targówek district, at ul. Głębocka 9/U1. Consultations are in Polish, Ukrainian or Russian. No referral or insurance is needed. You can choose a time on the booking page.
Short answers
Is CIN cancer?
No. CIN means changed cells within the surface layer of the cervix that have not crossed the basement membrane. CIN 2 and CIN 3 are called precancer: left untreated, some of these changes can turn into cancer over the years, which is why they are treated in advance.
Does CIN 1 need treatment?
Usually not. In more than half of cases CIN 1 clears on its own within a year or two. The HPV test is repeated after a year, often with cytology. Treatment is discussed if the changes persist for two years or longer.
What is the difference between CIN 2 and CIN 3?
Depth: in CIN 2 the changed cells take up to two thirds of the thickness of the epithelium, in CIN 3 more than two thirds or the full thickness. CIN 3 is always treated; with CIN 2, observation is acceptable for young women planning a pregnancy.
Are CIN and LSIL/HSIL the same thing?
They are two ways of recording the grade of change. LSIL corresponds to CIN 1, HSIL to CIN 2 and CIN 3. Cytology uses only LSIL and HSIL, while CIN is a histology term — it comes from the biopsy result.
Can I get pregnant after a conization?
Yes. Pregnancy after a conization or loop excision is possible. The risk of preterm birth is somewhat higher and depends on how much tissue was removed, so the doctor looking after the pregnancy should be told about the procedure.
How long does a cervical biopsy result take?
Usually 7 to 14 days. When the result is ready, we go through it at a visit and decide what comes next: observation or treatment.
Sources
The primary sources this text rests on. Links open in a new tab.
- Perkins RB et al. 2019 ASCCP Risk-Based Management Consensus Guidelines for Abnormal Cervical Cancer Screening Tests and Cancer Precursors. J Low Genit Tract Dis 2020;24:102–131the ASCCP guidelines — when CIN is observed, when it is treated and how follow-up after treatment works
- Darragh TM et al. The Lower Anogenital Squamous Terminology Standardization Project for HPV-Associated Lesions (LAST). J Low Genit Tract Dis 2012;16:205–242the LAST project — why histology reports say LSIL and HSIL with CIN in brackets, and why CIN 2 is stained for p16
- Östör AG. Natural History of Cervical Intraepithelial Neoplasia: A Critical Review. Int J Gynecol Pathol 1993;12:186–192a review of the natural history of CIN — how often CIN 1 regresses and how often it progresses
- Tainio K et al. Clinical course of untreated cervical intraepithelial neoplasia grade 2 under active surveillance: systematic review and meta-analysis. BMJ 2018;360:k499a meta-analysis of what happens to CIN 2 over two years of surveillance without treatment
- McCredie MRE et al. Natural history of cervical neoplasia and risk of invasive cancer in women with cervical intraepithelial neoplasia 3: a retrospective cohort study. Lancet Oncol 2008;9:425–434a cohort study of cancer risk with CIN 3 left untreated and after treatment
- Kyrgiou M et al. Adverse obstetric outcomes after local treatment for cervical preinvasive and early invasive disease according to cone depth: systematic review and meta-analysis. BMJ 2016;354:i3633a meta-analysis of how excision depth relates to the risk of preterm birth
This text describes the general picture and does not replace a consultation. Timings and indications differ from woman to woman and are decided at the appointment, from your history and test results.
