title: Outcomes after physical examination-indicated cerclage in twin gestations.
abstract: OBJECTIVE
  To compare outcomes of physical examination-indicated cerclage in women with twin gestations to those with singleton gestations and to identify whether risk factors for extremely preterm birth (before 28 weeks) differ between these 2 groups.
  
  
  METHODS
  This is a single institution retrospective cohort study of women who underwent a physical examination-indicated cerclage between Jan. 1, 1980, and Aug. 15, 2012. Differences in characteristics and outcomes were compared between women with twin and singleton gestations. A multivariable analysis was performed to examine whether twin gestation was independently associated with delivery before 28 weeks and whether any effect modification was present between risk factors for preterm birth and the presence of a twin gestation.
  
  
  RESULTS
  Of the 442 women who underwent a cerclage during the period of study, 104 (23.5%) had twins. Mean gestational age and digital cervical length at placement did not differ by plurality. Although twins were more likely to deliver at a slightly earlier median gestation than singletons (31.9 weeks; interquartile range, 24.9-35.1 vs 32.7 weeks; interquartile range, 24.6-38.3; P = .015), the frequency of delivery before 28 weeks did not differ between these 2 groups (33.7% vs 35.8%, P = .69). Greater cervical dilation and prolapsing membranes were identified as risk factors for birth <28 weeks in both groups; digital cervical length <2 cm appeared to be a risk factor particularly for women with twin gestations.
  
  
  CONCLUSIONS
  Women with a twin pregnancy who received a physical examination-indicated cerclage had similar risk factors for extreme preterm birth and may experience similar obstetric outcomes as women with singleton gestations.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Miller
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Priya V
authors.initials: PV
authors.lastname: Rajan
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: William A
authors.initials: WA
authors.lastname: Grobman
mesh_terms: D000328:Adult; D023802:Cerclage, Cervical; D015331:Cohort Studies; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D015999:Multivariate Analysis; D010808:Physical Examination; D011247:Pregnancy; D059285:Pregnancy, Twin; D047928:Premature Birth / Q000209:etiology / Q000517:prevention & control*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D002581:Uterine Cervical Incompetence / Q000175:diagnosis / Q000601:surgery*
keywords: cerclage; examination-indicated cerclage; predictors; preterm birth; twins