The effect of route of delivery on regression of abnormal cervical cytologic findings in the postpartum period

OBJECTIVES: We sought to determine whether pregnant women with abnormal antepartum cervical cytologic findings differ in their postpartum rates of regression with respect to mode of delivery. STUDY DESIGN: Between 1990 and 1997, 446 pregnant women with antepartum abnormal cervical cytologic findings were identified. Complete demographic, clinical, and cytologic reports were available for 138 women. Papanicolaou smear data were collected and separated into three groups by use of the Bethesda classification system (atypical squamous cells of undetermined significance, low-grade squamous intraepithelial cells, and high-grade intraepithelial cells). Postpartum regression rates of antepartum Papanicolaou smears, with respect to degree of squamous epithelial cell abnormality and mode of delivery, were analyzed by Fisher's exact and Wilcoxon rank sum tests. RESULTS: Of the 138 women, 109 (79%) were delivered vaginally and 29 (21%) by cesarean section. No statistically significant difference was found between women delivered vaginally and those delivered by cesarean section with respect to age, parity, and smoking history within the three groups (atypical squamous cells of undetermined significance, low-grade squamous intraepithelial cells, and high-grade squamous intraepithelial cells). The overall postpartum regression rate for the 59 women with antepartum high-grade squamous intraepithelial cells was 48%. Of the 47 women with high-grade squamous intraepithelial cells who were delivered vaginally, 28 showed regression in the postpartum period versus none of the 12 women delivered by cesarean section (60% vs 0%, p < 0.0002). CONCLUSION: Postpartum spontaneous regression of Papanicolaou smears consistent with high-grade squamous intraepithelial cells occurs with increased frequency among women who are delivered vaginally versus by cesarean section.