What is cervical intra-epithelial neoplasia (CIN)?

Cervical intra-epithelial neoplasia (CIN) means abnormal changes of the cells that line the cervix. CIN is not cancer. But if the abnormal area is not treated, over time it may develop into cancer of the cervix (cervical cancer).

CIN does not cause any symptoms. You are not likely to find out you have it unless you have cervical screening. Screening uses tests to find abnormal changes and to check whether they should be treated.

For some people with CIN, the abnormal changes go back to normal naturally. But if you do need treatment, it is usually very effective. Treatment removes or destroys the abnormal cells and prevents cancer developing in the future.

Causes of CIN


The main cause of CIN is the human papilloma virus (HPV). There are over 100 types of HPV. Some types can affect the cervix and cause the abnormal cell changes that may develop into cervical cancer. These types of HPV are called high-risk HPV.

HPV is very common, and most people are affected by it at some point. Usually the body’s immune system gets rid of the virus naturally. There are no symptoms, and often the virus does not cause damage. Most people will never know they had it.

In some people, the immune system does not clear the infection and the virus stays in the body for longer. If the cervix is affected by high-risk HPV, it means the virus may cause damage. Over a long time, this damage can develop into CIN.

High-risk HPV can be passed on through any type of sexual contact. Using a condom does not always stop it passing from person to person. HPV can affect people who:

  • have had one or more sexual partners
  • have had sex with men or with women
  • are in a long-term relationship with one person.

If you are in a sexual relationship, it is likely your partner has already been affected by HPV. This is unlikely to cause them any harm. They do not need to be tested or treated for it.

A vaccine can help prevent high-risk HPV infection and reduce the risk of CIN developing. The vaccine is most effective if you have not been exposed to the virus. The NHS offers the vaccine to girls from the age of 12 or 13. This is because they are less likely to be sexually active or have HPV already.


Your risk of developing CIN is higher if you smoke. This may be because:

  • smoking makes your immune system less effective at clearing HPV
  • the chemicals in tobacco can damage your cells.

We can help you give up smoking.

Signs and symptoms of CIN

CIN and HPV do not cause any symptoms. So it is important to have regular cervical screening tests to check for abnormal cell changes. If needed, these changes can be treated to prevent cancer.

Diagnosing CIN

The cervical screening test does not show if you have CIN. But if your cervical screening test result is abnormal, you may have a test using a microscope called a colposcopy. This looks at the cervix in more detail – it shows abnormal areas and how abnormal the cells there are. It can be used to diagnose CIN.

Sometimes the doctor or nurse can see the abnormal cells during a colposcopy, but it is not clear how serious the changes are. If this happens, they will take a small sample (biopsy) of the cells. This will be examined under a more powerful microscope to check if you need treatment. It may take 2 to 3 weeks to get the biopsy results. You can ask your doctor or nurse when you will get them.

Grading of CIN

CIN is graded by how deep the cell changes go into the surface of the cervix. It is graded into:

  • CIN 1
  • CIN 2
  • CIN 3.


CIN 1 means one third of the thickness of the surface layer is affected.

Cells showing CIN 1 will often return to normal without any treatment. You will have further cervical screening tests or colposcopies to check the cells have improved. If these tests show the CIN 1 is not improving, you may be offered treatment.


CIN 2 means two thirds of the thickness of the surface layer is affected.

CIN 2 has a higher risk of developing into cervical cancer. You are usually offered treatment to prevent this happening.


CIN 3 means the full thickness of the surface layer is affected.

CIN 3 is also known as carcinoma-in-situ. This sounds like cancer, but CIN 3 is not cervical cancer. Cancer develops when the deeper layers of the cervix are affected by abnormal cells.

CIN 3 has a higher risk of developing into cervical cancer. You are usually offered treatment to prevent this happening.

Treating CIN

Sometimes the doctor or nurse can see that the cells are very abnormal during the colposcopy. They may offer you treatment to remove these cells straight away.

Before any treatment, the doctor or nurse should give you time and information to make a decision.

Or after a colposcopy, you may be offered treatment to remove an area of CIN. There are different types of treatment. You usually only need one treatment to remove the abnormal cells completely.

They will only offer you treatment if they are sure the cells are very abnormal and there is a risk of cancer developing.

Follow-up for CIN

Treatments for CIN are usually very successful. To check, you will be asked to have another cervical screening test about 6 months after your treatment. Your sample will be carefully checked for signs of abnormal cells and high-risk HPV. What happens next depends on the results:

  • If the sample shows no high-risk HPV and normal cells or only slightly abnormal changes, you will be asked to have cervical screening again in 3 years. Your risk of developing more serious abnormal changes in this time is very low. 
  • If the sample shows high-risk HPV or more abnormal changes, you will be asked to have a more detailed check-up with another colposcopy.

For a few people, the colposcopy shows that an abnormal area of cells has come back and more treatment is needed. This is not very common. The same types of treatment can often be used again to remove or destroy the abnormal area of cells.

Very occasionally, if the abnormal cells keep coming back after treatment, your doctor might suggest having surgery to remove the cervix completely. This usually means having an operation called a hysterectomy. Your doctor will explain if they think this is right for you.

After a hysterectomy, you may still need tests to check for abnormal cells. This is similar to having a cervical screening test, but the sample of cells is taken from the top of the vagina. It is sometimes called a vaginal vault smear.

Your feelings

Finding out you are affected by CIN can be stressful and hard to cope with. The tests and treatments used for CIN are very personal. Many people find it a bit embarrassing. For some, the thought of having procedures is frightening and stressful.

It may help to remember that the aim is to stop cancer before it develops. Treating a small area of abnormal cells is usually a simple and effective way to do this.

You are likely to need several appointments to treat CIN and then check how effective treatment has been. People often feel anxious waiting for the next appointment, treatment or more test results.

Some people feel ashamed or embarrassed about CIN. It is natural to have mixed emotions, including feeling uncertain or alone. You may have questions or worry what others will think.

If you are finding it hard to cope, it may help to talk about it with someone:

  • You could talk to a family member or friend.
  • Your GP or practice nurse can answer any questions you have and explain how they can support you.
  • Sometimes it is easier to talk online to people in a similar situation. Our Online Community offers this kind of support.
  • You can call one of our cancer support specialists for more information and support.