What is cervical intra- epithelial neoplasia (CIN)?

Cervical intra-epithelial neoplasia (CIN) is when there are changes in the surface (squamous) cells of the cervix. It’s not a cancer. But because CIN can increase the risk of cervical cancer developing, it is called a pre-cancerous condition.

Not all causes of CIN are known but smoking has been found to increase the risk of it developing. Infection with some types of human papilloma virus (HPV) is thought to be the main cause.

A vaccine that protects against two of the most common types of HPV is now available to girls aged 12-13. HPV vaccines don’t work against all types of HPV so it’s still really important to go for your cervical screening test.

CIN doesn’t always need to be treated. But if treatment is necessary, it’s usually successful.

Both HPV and CIN have no symptoms, so regular cervical screening tests are really important to find any early cell changes.

What is CIN?

Cervical intra-epithelial neoplasia (CIN) is a term used to describe changes in the squamous cells of the cervix.

CIN is not cancer, but treatment may be needed to prevent squamous cell cervical cancer developing. You may hear some doctors use the term pre-cancerous condition to describe CIN.

Treatment isn't always needed for CIN, but if you do need treatment it's usually very successful.

Causes of CIN

Not all the causes of CIN are known. But they include:


Women who smoke are almost twice as likely to develop CIN as non-smokers.

Human papilloma virus (HPV)

The main cause of CIN is infection of the cervix with certain types of human papilloma virus (HPV). There are over 100 types of the virus, and the most common types can cause warts on the hands or verrucas on the feet. Some types can affect the genital area including the cervix, although not all of these will show any symptoms such as warts. The types of HPV that cause genital warts are not the same as the types that can lead to CIN. The types that cause genital warts are known as low-risk HPV types.

The human papilloma virus is sexually transmitted, and the possibility of contact with it increases with the number of sexual partners a woman or her partner has had. It’s more common in women who become sexually active at a young age, when their cervix may be immature and more vulnerable.

HPV is so common that most sexually active women will be exposed to it at some time in their life. There is evidence that barrier methods of contraception, such as the cap or condoms, give some protection against the spread of HPV, but they won’t cover all the susceptible areas. In most women, their body’s own immune system will get rid of the HPV naturally without them ever knowing it was there.

Some types of HPV can make women more likely to develop CIN. These are known as high-risk types of HPV. In some women they cause changes in the cervix, which show up as an abnormality during the screening tests. Very rarely, these changes can go on to develop into CIN or cervical cancer if they are left untreated. Through regular cervical screening, the changes caused by HPV can be picked up early and any treatment needed is simple and effective.

HPV vaccines

Two vaccines have been produced to prevent HPV. These are called Gardasil® and Cervarix®. It's hoped that these vaccines will prevent at least 7 in 10 (70%) of the most common type of cervical cancer (squamous cell). But HPV vaccinations won't replace the need for regular cervical screening tests in women.

Any vaccine works best if it's given to children before they reach puberty. As the HPV virus is passed on during sex, the vaccine is most effective if it's given to girls before they might start having sex. Girls aged 12–13 are now routinely offered the HPV vaccine Gardasil. Gardasil protects against two of the most important types of HPV (HPV 16 and 18) that can cause cervical cancer. It's also effective against the types of HPV that can cause genital warts.

We have fact sheets that explain HPV and cancer, and HPV vaccines, in more detail.

Symptoms of CIN and HPV

CIN and HPV have no symptoms, so it's essential for women to have regular cervical screening tests to detect any early cell changes.

Back to Cervical screening and CIN

The cervix

The cervix is the lower part of the womb (uterus). It’s often called the neck of the womb.

Diagnosing and grading CIN

A colposcopy is used to confirm whether you have cervical intra-epithelial neoplasia (CIN) and how severe it might be.

Treating CIN

If you have been diagnosed with CIN, you may have treatment to remove the abnormal cells. There are different types of treatment.

After treatment for CIN

Most women feel fine after treatment for CIN but some may feel unwell for a few hours. You will be referred for regular screening tests.

Grading CIN

Knowing the grade of CIN will help your specialist plan the best treatment for you.