Efficacy of Cerclage on Cervical Length

Preterm delivery is complicated with considerable high morbidity & mortality of newborns. Incompetent cervix is one of the important causes of preterm labor wherein such cases cerclage (Mc. Donald & Shirodkar) has been used for prophylaxy. Cerclage decreases the incidence of preterm labor with unknown Mechanism. In some Recent studies it was suggested that increasing in cervical length after cerclage is the main cause for decreasing preterm labor. This study was carried out to see if cerclage has any therpeutic effect on cervical length. This clinical trial was performed on 18 pregnant women needing cerclage for the histoy of previous second trimester pregnancy loss or patients whose cervical length in transvaginal sonography was < 30mm. Cervical length was measured twice by transvaginal sonography; 48 hours before and 72 hour after cerclage. Afterwards, these two measurements were compared. Paired t-test was applied for statistical evaluation. Mean cervical length before and after the cerclage was 25.8  2.8 mm and 26.7  2.4 mm, respectively. There was no statistically significant difference between before and after-cerclage cervical length. It was concluded that increase in cervical length after cerclage is not statisfically significant (P > 0.05). The mechanism of cerclage in preterm labor in case of incompetency of cervix was not increasing the cervical length.