title: Cervical length and dilatation of the internal cervical os detected by vaginal ultrasonography as markers for preterm delivery: A systematic review.
abstract: OBJECTIVE
  We performed a systematic review to evaluate endovaginal cervical ultrasonography as a predictor of preterm delivery.
  
  
  METHODS
  Selection criteria were original published English-language reports of prospective studies including women at <37 weeks' gestation with intact amniotic membranes. Parameters and outcomes were cervical length or dilatation of the internal cervical os and preterm delivery.
  
  
  RESULTS
  In 3 subgroups of studies including patients with preterm labor or low-risk, symptom-free patients with early (20-24 weeks) or late (27-32 weeks) ultrasonographic examination, optimal cutoff values for cervical lengths ranged between 18 and 30, 25 and 35, or 25 and 39 mm. At these cutoff values, sensitivity rates were between 68% and 100%, 33% and 54%, or 63% and 76%, and specificity rates were between 44% and 79%, 73% and 91%, or 59% and 69%, respectively. Sensitivity rates for dilatation of the internal cervical os were 70% to 100%, 16% to 25%, or 33%, and specificity rates were 54% to 75%, 95% to 99%, or 92%, respectively.
  
  
  CONCLUSIONS
  In patients with symptoms of preterm labor, endovaginal cervical ultrasonography appears to be an effective predictor of preterm delivery.
authors.affiliation: Department of Obstetrics and Gynecology, University of Vienna, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Leitich
authors.forename: M
authors.initials: M
authors.lastname: Brunbauer
authors.forename: A
authors.initials: A
authors.lastname: Kaider
authors.forename: C
authors.initials: C
authors.lastname: Egarter
authors.forename: P
authors.initials: P
authors.lastname: Husslein
mesh_terms: D002584:Cervix Uteri / Q000000981:diagnostic imaging* / Q000502:physiology*; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000592:standards*