title: Transvaginal sonographic cervical length for the prediction of spontaneous preterm birth in twin pregnancies: a systematic review and metaanalysis.
abstract: OBJECTIVE
  To assess the accuracy of transvaginal sonographic cervical length (CL) in predicting spontaneous preterm birth in women with twin pregnancies.
  
  
  METHODS
  Systematic review and metaanalysis of predictive test accuracy.
  
  
  RESULTS
  Twenty-one studies (16 in asymptomatic women and 5 in symptomatic women) with a total of 3523 women met the inclusion criteria. Among asymptomatic women, a CL <or=20 mm at 20-24 weeks' gestation was the most accurate in predicting preterm birth <32 and <34 weeks' gestation (pooled sensitivities, specificities, and positive and negative likelihood ratios of 39% and 29%, 96% and 97%, 10.1 and 9.0, and 0.64 and 0.74, respectively). A CL <or=25 mm at 20-24 weeks' gestation had a pooled positive likelihood ratio of 9.6 to predict preterm birth <28 weeks' gestation. The predictive accuracy of CL for preterm birth was low in symptomatic women.
  
  
  CONCLUSIONS
  Transvaginal sonographic CL at 20-24 weeks' gestation is a good predictor of spontaneous preterm birth in asymptomatic women with twin pregnancies.
authors.affiliation: Perinatology Research Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development/National Institutes of Health/Department of Health and Human Services, Bethesda, MD, USA.
authors.forename: Agustín
authors.initials: A
authors.lastname: Conde-Agudelo
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Hassan
authors.forename: Lami
authors.initials: L
authors.lastname: Yeo
mesh_terms: D002584:Cervix Uteri / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011272:Pregnancy, Multiple; D047928:Premature Birth / Q000000981:diagnostic imaging* / Q000453:epidemiology; D018570:Risk Assessment; D014427:Twins; D016216:Ultrasonography, Prenatal