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 surface (epithelial tissue) of the cervix. 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 cancer is formed, it takes years to develop. 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 common 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 among women 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 itself will get rid of the virus. There are more than 100 strains of HPV. Some strains, 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 at some time.

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

We do not know exactly 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 clear 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 be done to 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 preference of the patient and their 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 in 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 the elimination of abnormal cells that could become cancerous.

Extraction procedures (resection) include:

  • Loop electrosurgical excision procedure: this technique uses a small loop of electrically charged wire 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) -This is a surgical procedure in which a cone-shaped piece containing the lesion is removed.

It used to be the preferred method for the treatment of 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 hemorrhage.
  • 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 progresses, it does so slowly.

The risk of recurrence is highest during the first 2 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 8 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.


Human papilloma virus, which is the main 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 to not get involved in sex. The use of condoms can reduce the risk of HPV infections, but they are not totally effective.

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