Cervical cancer screening in pregnancy: Impact of the latest ASCCP guidelines

June 1, 2008

Deferred treatment of pregnant women's cytologic abnormalities until after delivery at term-except for frankly invasive cervical cance-are among key recommendations of 2006 ASCCP guidelines.

Significantly fewer women are getting cervical cancer-and dying from it-thanks to the widespread use of the Pap test over the past 50 years.1 Since at least the mid-1960s, a Pap test has been a routine part of prenatal care and the postpartum visit.2

While pregnancy, per se, does not increase a woman's risk of developing cervical cancer, it gives you a chance to assess whether a patient has had a Pap within the recommended screening intervals. Our goals in this article are to discuss the timing of cervical cytology screening in pregnancy and the latest recommendations for managing abnormal Pap tests during pregnancy and to offer some helpful tips for performing colposcopy in pregnancy.

Some 42% of cervical cancers are diagnosed during the reproductive years (ages 15–44).3 It should come as no surprise, therefore, that invasive cervical cancer has been reported in up to 0.1% of prenatal patients at large referral centers. The rate of preinvasive CIN 3 is much higher.4 Most women diagnosed with cervical cancer have not had a Pap test within the previous 5 years, if ever.5

Does every woman need a Pap test as part of her prenatal care? Clearly, the Pap history of every new prenatal patient must be carefully reviewed. If she has not had a Pap within the recommended screening interval for her age and history, the initial prenatal exam is the ideal time to perform it. On the other hand, if a woman wouldn't be due for a Pap test were she not pregnant, adding a cytology exam at this time does little to prevent cervical cancer. There's no good evidence that pregnancy increases the risk of developing cervical lesions in human papillomavirus (HPV)-positive women, nor does existing dysplasia progress more rapidly during pregnancy.6

The American College of Obstetricians and Gynecologists and the American Cancer Society agree that a woman should have her first Pap test at age 21 or about 3 years after the onset of vaginal intercourse.7,8 Cytology screening should continue annually until age 30 if conventional cytology is used. If liquid-based cytology is used, however, the American Cancer Society allows for Pap tests every other year during this period. After age 30, if the previous three Pap test results were reported as negative for intraepithelial lesion or malignancy, the interval between Pap tests may be extended to 2 to 3 years. HPV DNA testing may be added to Pap screening at age 30.7,8 As noted above, there's no evidence to suggest modifying these screening intervals during pregnancy.

The technique for performing the Pap test in pregnancy is no different than for a nonpregnant patient, although a bit of additional gentleness is appropriate, as the tissue is likely to bleed more easily. Both broom device and Ayre spatula with cytobrush can be safely used,9 but avoid a moistened cotton swab; it's less sensitive than the first two.4

Be sure to alert the pathologist to your patient's pregnancy by noting it on the cytology requisition, because otherwise several cytologic findings particular to pregnancy can be mistaken for neoplastic abnormalities. For example, degenerated decidual cells and clusters of cytotrophoblast cells might mimic high-grade squamous intraepithelial lesions (HSIL). Also, syncitiotrophoblast cells with perinuclear cavitation and nuclear atypia are occasionally mistaken for HPV changes, and Arias-Stella reaction may produce cells that appear similar to adenocarcinoma.4