title: Is cerclage height associated with the incidence of preterm birth in women with an ultrasound-indicated cerclage?
abstract: OBJECTIVE
  Our aim was to determine whether there was a cerclage height threshold associated with spontaneous preterm birth in patients with an ultrasound-indicated cerclage.
  
  
  METHODS
  We performed a retrospective cohort study of women with an ultrasound-indicated cerclage. Functional cervical length and the cerclage height (distance from cerclage to the external cervical os) were obtained. Our cohort was grouped into thirds, based on cerclage height percentile. Our primary outcome was spontaneous preterm birth less than 35 weeks.
  
  
  RESULTS
  There were 20 women in group 1 (< 18 mm), 25 in group 2 (13-17 mm), and 25 in group 3 (> or = 18 mm). Women with cerclage height 18 mm or greater had a lower incidence of spontaneous preterm birth less than 35 weeks (4%) when compared with those with a cerclage height less than 18 mm (33%) (relative risk, 0.69; 95% confidence interval, 0.55-0.86).
  
  
  CONCLUSIONS
  Cerclage height of 18 mm or greater is associated with a reduction in spontaneous preterm birth for women with an ultrasound-indicated cerclage.
authors.affiliation: Division or Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Stacey
authors.initials: S
authors.lastname: Scheib
authors.forename: John F
authors.initials: JF
authors.lastname: Visintine
authors.forename: Gennady
authors.initials: G
authors.lastname: Miroshnichenko
authors.forename: Christopher
authors.initials: C
authors.lastname: Harvey
authors.forename: Keith
authors.initials: K
authors.lastname: Rychlak
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Berghella
mesh_terms: D000328:Adult; D023802:Cerclage, Cervical / Q000009:adverse effects* / Q000379:methods* / Q000706:statistics & numerical data; D002584:Cervix Uteri / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D047928:Premature Birth / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D014463:Ultrasonography; D055815:Young Adult