Cervical Intraepithelial Neoplasia: Classification, Causes, Symptoms, Treatment and Prevention

What is Cervical Intraepithelial Neoplasia?

CIN is a precancerous condition in which abnormal cells grow on the surface of the cervix, which is the opening between the vagina and the uterus in women.

“Intraepithelial” means that abnormal cells are present on the cervix’s surface (epithelial tissue). The word “neoplasia” refers to the growth of new cells. Another name for NIC is cervical dysplasia.

It is important to remember that most people with CIN do not get cancer. If the tumor is formed, it takes years to develop. The time necessary for doctors to find and eliminate problem areas.


Cervical intraepithelial neoplasia can be classified according to the amount of affected epithelial tissue:

  • Low-grade neoplasia (CIN 1) refers to dysplasia that involves approximately one third of the thickness of the epithelium.
  • CIN 2 refers to abnormal changes in about one-third to two-thirds of the epithelial layer.
  • IAS 3 (the most severe form) describes a condition that affects more than two-thirds of the epithelium.

What are the symptoms of Cervical Intraepithelial Neoplasia?

Cervical Intraepithelial Neoplasia usually does not cause any symptoms. Abnormal cells are found only after a routine Pap test.

How standard is the NIC?

Approximately 250,000 to 1 million women in the United States are diagnosed with NIC each year.


The condition is found most frequently among women of childbearing age, particularly those aged 25 to 35 years.

What causes the NIC?

Cervical Intraepithelial Neoplasia usually occurs after a woman is infected with the human papillomavirus (HPV). This is a virus that is transmitted through sexual contact.

In many cases, the immune system will get rid of the virus. There are more than 100 strains of HPV. Some songs, such as HPV-16 and HPV-18, are more likely to infect the reproductive tract in women and cause CIN.

It is believed that more than 75% of sexually active women are or were infected with HPV.

Approximately 50% of HPV infections occur in women between the ages of 15 and 25. Most of the time, diseases disappear, causing permanent problems.

We do not know why some women develop CIN after becoming infected with HPV. Some high-risk strains of HPV and the duration of infection may play a role.

Other risk factors include:

  • The age of a woman
  • To smoke cigarettes
  • Use of immunosuppressive drugs
  • Factors that make the immune system weaker and increase the risk of HPV infections include:
  • Have sex with multiple partners
  • Be sexually active before age 18
  • Infection with the human immunodeficiency virus (HIV)

How is the NIC diagnosed?

Since NIC usually does not cause any symptoms, a Pap test is needed to find abnormal cells.

If the Pap test is not straightforward or abnormalities are found, the next step could be a colposcopy to examine the cervix and surrounding structures under a microscope.

The procedure can be performed in a doctor’s office, where a set of binoculars with a light (a colposcope) is centered on the cervix.

The doctor will look through colored lenses to see if there are abnormal cells in the cervix or vaginal walls.

A biopsy may remove tissue samples for examination in a laboratory. A DNA test can be ordered to see if there is a high-risk form of HPV.


Treatment will depend on several factors, including the severity of the NIC, the age of the patient and their general medical condition, and the patient’s preference and doctor.

Procedures to treat the cervix can affect the ability to have children, so women should discuss several options with their health care providers.

In the case of low-grade cervical intraepithelial neoplasia, treatment is usually not necessary. In most of these cases, the condition is resolved.

Only about 1% of low-grade CIN cases progress to cervical cancer.

A health care provider may choose a conservative approach that requires periodic Pap tests to monitor for any changes in abnormal cells.

In the case of a moderate and severe NIC, the treatment focuses on eliminating abnormal cells that could become cancerous.

Extraction procedures (resection) include:

  • Loop electrosurgical excision procedure: this technique uses a small electrically charged wire loop to remove the tissue.

Unlike ablation procedures, this method can remove tissue samples for later analysis. It can be used to treat severe CIN.

About 1% to 2% of patients may experience complications after the procedure, such as delayed bleeding or narrowing of the cervix (stenosis).

  • Cold knife cone biopsy (conization) is a surgical procedure in which a cone-shaped piece containing the lesion is removed.

It used to be the preferred method for treating cervical intraepithelial neoplasia, but now it is reserved for the more severe forms of the disease.

  • The conization can provide a tissue sample for further testing. It has a slightly higher risk of complications, including cervical stenosis and postoperative bleeding.
  • Hysterectomy: Removal of the uterus may be an option in cases where CIN persists or does not improve after other procedures are used.

Most of the time, cases of CIN can be treated successfully. Ablation and resection are effective in approximately 90% of all cases, with a 10% chance of recurrence after treatment. Rarely progresses to cancer, and when it goes, it does so slowly.

The risk of recurrence is highest during the first two years after treatment. Ablation and resection procedures can reduce the risk of cervical cancer by 95% in women with high-grade dysplasia in the first eight years after treatment.

Patients are recommended to have Pap tests every 3 or 6 months for 1 or 2 years after treatment. After that, they can resume the annual Papanicolaou tests.


The human papillomavirus, which is the leading cause of cervical intraepithelial neoplasia, can be transmitted through sexual contact, including hand to genital or oral to genital contact, as well as direct genital contact.

The only way to effectively prevent HPV infections is not to get involved in sex. Condoms can reduce the risk of HPV infections, but they are not effective.

HPV vaccines: The Food and Drug Administration has approved a Gardasil vaccine that is effective against the four types of HPV most closely linked to CIN.