Rates of cervical cancer have decreased by more than 50 percent in the past 30 years because of widespread screening with cervical cytology. Despite the proven success of screening, however, it is estimated that more than one half of the women in whom cervical cancer is diagnosed each year have never had cervical cytology testing or have not been tested within the previous five years. One approach to further reduce the incidence of cervical cancer is to increase screening rates among women who have never been screened or who are screened infrequently. The American College of Obstetricians and Gynecologists (ACOG) recently updated its recommendations on screening for cervical cancer, including screening intervals.

Cervical cancer screening should begin at 21 years of age, regardless of the woman's age at first sexual intercourse. Although women are often infected with human papillomavirus (HPV) shortly after the initiation of vaginal intercourse, these infections are usually cleared by the immune system within one to two years without producing neoplastic changes. Because invasive cervical cancer is rare in women younger than 21 years, screening in this population may lead to unnecessary and potentially harmful treatment, and is not recommended. Sexually active patients younger than 21 years should be counseled and tested for sexually transmitted infections, and should be counseled about safe sex and contraception. This can be performed without cervical cytology.

Women 21 to 29 years of age should be screened every two years using liquid-based or conventional cytology, then every three years beginning at age 30 if they have had three consecutive normal tests. Women with any of the following risk factors require screening at more frequent intervals: those infected with human immunodeficiency virus; immunosuppressed women (e.g., renal transplant recipients); women who were exposed in utero to diethylstilbestrol; and those who were previously treated for cervical intraepithelial neoplasia (CIN) grade 2, CIN 3, or cancer. Women previously treated for CIN 2, CIN 3, or cancer are at high risk of persistent or recurrent disease for at least 20 years after treatment, and should be screened annually during this time. Regardless of the frequency of screening, physicians should counsel their patients to have annual gynecologic examinations, even if cervical cytology is not performed at every visit.

Screening with a combination of cytology plus HPV DNA testing is appropriate in women older than 30 years. If both tests are negative, the patient should wait at least three years before rescreening. HPV DNA testing may also be used as a follow-up test after CIN 1 or negative findings on colposcopy in women with a history of any of the following cytologic diagnoses: atypical squamous cells of undetermined significance (ASC-US);atypical squamous cells–cannot exclude high-grade squamous intraepithelial lesions (ASC-H); low-grade squamous intraepithelial lesions (LSIL); or atypical glandular cells. HPV DNA testing can also be used as follow-up after treatment for CIN 2 and CIN 3. It should not be used in women younger than 21 years, and if inadvertently performed in a younger woman, a positive result should not influence treatment. Women who have been immunized against HPV-16 and HPV-18 should be screened by the same regimen as nonimmunized women.

Because cervical cancer develops slowly and risk factors decrease with age, it is reasonable to discontinue screening between 65 and 70 years of age in women who have had three or more negative cytology test results in a row and no abnormal test results in the past 10 years. If screening is discontinued, risk factors should be assessed annually to determine whether screening should be reinitiated.

Routine cytology testing should be discontinued in women who have had a total hysterectomy for benign indications if they have no history of high-grade CIN. Women who have had a hysterectomy with removal of the cervix and have a history of CIN 2 or CIN 3, or in whom a negative history cannot be documented, should continue to be screened even after the posttreatment surveillance period. Although the screening interval may be extended, there are no good data to support or refute discontinuing screening in this population.