Pregnancy-related changes: a retrospective review of 278 cervical smears.

Pregnancy-related physiologic changes are well recognized. However, the normal range of changes as reflected in the cervical smear have not been adequately described. Review of 278 abnormal cervical smears from 153 pregnant/preabortal and 125 postpartum/ abortal patients revealed the following: 21 high-grade squamous intraepithelial lesion (HGSIL) cases, 46 low-grade squamous intraepithelial lesion (LGSIL) cases, 185 atypical squamous cells of undetermined significance (ASCUS) cases, and 26 atypical glandular cells of undetermined significance (AGUS) cases. Surgical correlation (excluding 18 products of conception and 153 placentas) was available in 98 (35%) of the cases. Dysplasia was confirmed on biopsy of 11 cases cytologically diagnosed as HGSIL (7 CINII/III and 4 CIN I), 19 cases cytologically diagnosed as LGSIL (6 CIN II/III and 13 CIN I), 35 cases of ASCUS (4 CIN II/III and 31 CIN I), and 2 cases of AGUS (1 CIN III and 1 CIN I). Decidualization was present in six cervical and three endometrial biopsies. The remaining 180 cases revealed pregnancy-related changes in most of the atypical groups and a few in the dysplasia groups. With pregnancy, both cervical glands and stroma undergo physiologic changes. These result in squamous metaplasia due to ectropion and cells with hypervacuolated cytoplasm and atypical nuclei reflecting endocervical gland hyperplasia and/or Arias-Stella reaction. The decidual cells are large, with variably staining cytoplasm and a large nucleus. Degenerated decidual or trophoblastic cells can also shed from the endometrium and mimic HGSIL. Despite the caution required in this population, dysplastic changes should not be underestimated.