Cervical Dysplasia (CIN)

What cervical dysplasia is

The surface of the cervix is lined with cells that are constantly renewed. At the transformation zone, where the inner and outer cervical cells meet, cells are especially vulnerable to HPV. When high-risk HPV persists, it can make these cells grow abnormally. Under the microscope they look disorganized but have not invaded deeper tissue. That is dysplasia: not cancer, but a step on the path that can lead to cancer over many years if untreated.

Grades and terminology

Pap test (cytology) results use different terms:

• ASC-US: atypical cells of undetermined significance, the most common and mildest result
• LSIL: low-grade squamous intraepithelial lesion
• ASC-H: atypical cells, cannot exclude a high-grade lesion
• HSIL: high-grade squamous intraepithelial lesion
• AGC: atypical glandular cells, from the glandular lining, which needs further evaluation

Causes and risk factors

HPV is extremely common. Most sexually active people get it at some point, and the immune system clears most infections within 1 to 2 years. Dysplasia develops when a high-risk type persists. Factors that make persistence more likely:

• smoking, which weakens local immunity in the cervix
• a weakened immune system, including HIV, organ transplants and immune-suppressing medicines
• starting sex at a young age, and multiple partners
• long-term use of combined birth control pills (a small increase)
• not being vaccinated against HPV
• not having regular screening

Symptoms

Cervical dysplasia almost never causes symptoms. That is why screening is so important. Bleeding after sex, between periods or after menopause, or unusual discharge, are not typical of dysplasia but need checking, because they can be signs of cervical cancer or other conditions such as cervical polyps or infection.

Screening

US guidelines recommend screening for people with a cervix aged 21 to 65 (the American Cancer Society suggests starting at 25 with HPV testing):

• Ages 21 to 29: Pap test every 3 years. HPV testing from 25 is an alternative in some guidelines.
• Ages 30 to 65: primary HPV test every 5 years, HPV plus Pap (co-testing) every 5 years, or Pap alone every 3 years.
• Over 65: screening can usually stop after a history of normal results.

People with HIV, a weakened immune system or a history of high-grade dysplasia need more frequent screening. Vaccinated people still need screening.

What happens after an abnormal result

Follow-up depends on your result, HPV status, age and past history, using risk-based guidelines.

• Repeat testing in 1 year for low-risk results, such as ASC-US with a negative HPV test or LSIL with low overall risk.
• Colposcopy: a doctor looks at the cervix through a magnifying instrument after applying a vinegar solution, which makes abnormal areas turn white. It takes about 10 to 20 minutes in the office.
• Biopsy: small tissue samples are taken from abnormal areas during colposcopy. This gives the CIN grade. It feels like a pinch or cramp.
• Endocervical sampling of the canal when needed.

Treatment

CIN 1

Usually monitored with repeat testing, because most cases clear on their own. Treatment is considered if it persists for 2 years or more.

CIN 2 and CIN 3

Usually treated to remove or destroy the abnormal area. In people under 25, or those planning pregnancy, CIN 2 may be monitored closely instead, since it often regresses.

• LEEP (loop electrosurgical excision procedure): a thin wire loop with an electric current removes the abnormal area. Done under local anesthetic in about 10 minutes. The tissue is sent for testing.
• Cold knife cone biopsy: removes a cone of tissue with a scalpel, usually under general anesthesia, used for glandular abnormalities or when deeper tissue must be checked.
• Ablation: freezing (cryotherapy) or thermal or laser ablation destroys abnormal cells, used in selected cases when the whole area is visible.

After treatment

• Expect watery or brownish discharge and light bleeding for 2 to 4 weeks.
• Avoid sex, tampons and swimming for about 4 weeks, or as advised.
• Follow-up HPV testing is usually done 6 months later and then regularly for at least 25 years.
• Excision procedures slightly increase the risk of preterm birth in later pregnancies, which is one reason treatment is tailored for younger people.

Outlook

Treatment for high-grade dysplasia is very effective, and most people need only one procedure. Without treatment, a proportion of CIN 3 lesions progress to invasive cancer over years. With screening and follow-up, cervical cancer can almost always be prevented.

Prevention

• HPV vaccination: recommended at age 11 to 12 (can start at 9), and catch-up through age 26. Some adults aged 27 to 45 may benefit after discussion with their doctor.
• Regular screening at the recommended intervals.
• Stop smoking.
• Condoms reduce, but do not eliminate, HPV transmission.

Frequently asked questions

Is cervical dysplasia cancer?

No. Cervical dysplasia is a precancerous change, meaning cells look abnormal but have not invaded deeper tissue. Most mild dysplasia clears on its own. High-grade dysplasia is treated because, if left alone for years, some cases can turn into cancer.

What does CIN 1, 2 and 3 mean?

CIN stands for cervical intraepithelial neoplasia, graded by how much of the cervical lining is abnormal: CIN 1 is mild (lower third), CIN 2 moderate (up to two-thirds) and CIN 3 severe (full thickness). CIN 1 is usually monitored, while CIN 2 and 3 are usually treated.

Can cervical dysplasia go away on its own?

Yes, often. Most CIN 1 and many CIN 2 cases clear within 1 to 2 years as the immune system clears HPV, especially in younger people. Not smoking helps. Regular follow-up testing confirms whether it has resolved.

Does a LEEP affect pregnancy?

A LEEP slightly increases the risk of preterm birth in future pregnancies, especially if a larger area was removed or the procedure was repeated. Most people have normal pregnancies afterward. Tell your obstetric provider if you have had a LEEP or cone biopsy.

I got the HPV vaccine. Do I still need Pap tests?

Yes. The vaccine protects against the HPV types that cause most, but not all, cervical cancers, and it works best when given before any exposure. Vaccinated people should continue routine cervical screening.