Treatment for Cervical Intraepithelial Neoplasia and Risk of Preterm Delivery

Abstract

Effective treatment of cervical intraepithelial neoplasia (CIN) can prevent invasive cervical cancer. The trend away from cold-knife conization toward more conservative procedures continues, but it is possible that excisional or ablative treatments might increase the risk of preterm delivery by lessening the mechanical support lent by a shortened cervix. These procedures also could impair local immunity by destroying glandular epithelium, and they might alter the bacterial flora in the cervicovaginal region. This retrospective cohort study, carried out at a colposcopy clinic in Auckland, New Zealand in the years 1988-2000, compared delivery outcomes in 652 women treated for CIN by laser conization, laser ablation, or a loop electrosurgical excision procedure (LEEP) and 426 untreated women. All participants carried a singleton pregnancy to at least 20 completed weeks of gestation. The overall rate of preterm delivery (before 37 weeks gestation) was 13.8%. The most common cause, identified in 45% of cases, was premature rupture of membranes (pPROM). Rates of total pretrerm deliveries, pPROM, and spontaneous preterm labor were higher in treated than in untreated women. Preterm delivery was iatrogenic in 2.9% of the treated group and 5.2% of the untreated group. Adjusted relative risk (aRR) figures showed that treating CIN was not associated with an increased risk of total or spontaneous preterm deliveries, but a single laser conization treatment or LEEP was associated with an increased risk of pPROM leading to preterm delivery. The risk of pPROM increased with an increasing height of excised cervical tissue. Women with a vertical cone height of at least 1.7 cm of tissue removed had a greater than 3-fold increase in risk of preterm delivery compared with untreated women (aRR, 3.6). The risk of pPROM increased linearly with increasing cone height; no threshold value was identified. The risk of all preterm deliveries increased significantly with increasing cone height. Treatment variables did not interact significantly with age, parity, or smoking during pregnancy, Mode of treatment did not relate to cone height. Women who are aware of the risk of preterm delivery associated with treating CIN will be likelier to present at an early stage for antibiotic and steroid treatment. Cervical cerclage might have a role in managing women whose ultrasound studies show progressive cervical shortening during pregnancy.