title: Effectiveness of cerclage according to severity of cervical length shortening: a meta-analysis.
abstract: OBJECTIVE
  To estimate the effectiveness of cerclage according to degree of cervical length (CL) shortening.
  
  
  METHODS
  A meta-analysis was carried out of trials of women with singleton gestations and second-trimester transvaginal sonographic CL < 25 mm randomized to cerclage or no cerclage. The degree of CL shortening was correlated to the efficacy of cerclage in preventing preterm birth.
  
  
  RESULTS
  There was a significant reduction in preterm birth < 35 weeks in the cerclage compared with no cerclage groups in 208 singleton gestations with both a previous preterm birth and CL < 25 mm (relative risk, 0.61; 95% CI, 0.40-0.92). In these women, preterm birth < 37 weeks was significantly reduced with cerclage for CL < or = 5.9 mm, < or = 15.9 mm, 16-24.9 mm and < 25 mm. None of the analyses for 344 women without a previous preterm birth was significant.
  
  
  CONCLUSIONS
  Cerclage, when performed in women with a singleton gestation, previous preterm birth and cervical length < 25 mm, seems to have a similar effect regardless of the degree of cervical shortening, including CL 16-24 mm, as well as CL < or = 5.9 mm.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107, USA. vincenzo.berghella@jefferson.edu
authors.forename: V
authors.initials: V
authors.lastname: Berghella
authors.forename: S M
authors.initials: SM
authors.lastname: Keeler
authors.forename: M S
authors.initials: MS
authors.lastname: To
authors.forename: S M
authors.initials: SM
authors.lastname: Althuisius
authors.forename: O A
authors.initials: OA
authors.lastname: Rust
mesh_terms: D023802:Cerclage, Cervical / Q000379:methods*; D002584:Cervix Uteri / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D014463:Ultrasonography; D002581:Uterine Cervical Incompetence / Q000000981:diagnostic imaging / Q000601:surgery*