Route of Delivery on Regression of Abnormal Cervical Cytologic Findings in the Postpartum Period

Abstract & Commentary

Synopsis: Vaginal delivery results in a higher rate of spontaneous regression of HGSIL than Cesarean delivery.

Source: Ahdoot D, et al. Am J Obstet Gynecol 1998; 178:1116-1120.

This study examines the effect of the route of delivery on regression of CIN in 138 patients who had complete demographic clinical and cytologic reports, and who participated in postpartum follow-up. Twenty-six of the women had a smear showing ASCUS, 53 had LGSIL, and 59 had HGSIL. The Cesarean section rate did not differ among these groups. Likewise, age, parity, and a history of smoking were not significantly different. These women represent only about one-third of all of the women referred to the clinics performing this study. Unfortunately, data were lacking for the remaining two-thirds of the group, and they were not included in the study. However, there was no evidence that any type of systematic bias was the cause for the lack of complete information.

There was no significant difference in the regression of those women with ASCUS or LGSIL smears when they were compared by the route of delivery. (See Table.) However, there was a significant increase in the regression rate among women who were delivered vaginally when compared to Cesarean delivery.

Ahdoot and associates review possible explanations for the observed difference in HGSIL regression. They theorize that changes in the local immune response as part of the reparative process following vaginal delivery might be the cause. Likewise, the cause might be that significant abrasion of the cervical epithelium occurs at the time of delivery.

Table

Postpartum Regression of CIN

Vag
(%) 
CD
P
ASCUS
70
50
 0.6
LGSIL
64
64
1.0
HGSIL
60
  0
0.0002

Adapted from Ahdoot, et al. Am J Obstet Gynecol 1998;178:1116-1120.

Comment by Kenneth Noller, MD

The management of abnormal Pap smears in pregnancy is difficult. Even experienced colposcopists have trouble examining and properly classifying women with abnormal Pap smears during gestation. Most reported series have shown that there is a great likelihood of misdiagnosis in pregnancy, even with experience.

We all have noted that many women no longer have evidence of CIN following delivery. This has been reported many times in the literature. However, this current study appears to be the first that has compared vaginal to Cesarean delivery. In my view, it is not at all surprising that the those women who vaginally deliver had less persistence of disease than those who delivered abdominally. The abrasion of the cervical epithelium as a result of the fetus passing through the birth canal, as well as the required postpartum repair process, would seem to make it likely that CIN might disappear following vaginal delivery.

It is also not surprising that there was no difference seen between vaginal and abdominal delivery among women with ASCUS and low-grade smears. The regression rate of HPV/mild dysplasia/CIN I is at least 50%, and perhaps is as high as 70% after 1-2 years of follow-up. Thus, so many lesions would spontaneously disappear that it is unlikely that a significant difference would be noted (even if it exists) unless the study was large.