title: Comparison of transperineal and transvaginal sonography in predicting preterm delivery.
abstract: OBJECTIVE
  A major advantage of transperineal sonography (TPUS) is its ability to evaluate the cervix without causing any distortion. This study was performed to compare transvaginal sonography (TVUS) and TPUS at 24 weeks of gestation in predicting preterm delivery in low-risk pregnancy.
  
  
  METHODS
  Three hundred fifty-seven pregnant women underwent TVUS and TPUS at 24 weeks of gestation. The relationship between cervical length and preterm delivery was assessed. Accuracy values of TVUS and TPUS at 24 weeks of gestation were compared in predicting preterm delivery.
  
  
  RESULTS
  Preterm delivery (before 36 weeks of gestation) occurred in 22 pregnancies (6.2%). Mean cervical lengths measured by TVUS and TPUS were significantly different in preterm and term delivery groups (P < 0.05). Areas under the curves were 0.801 and 0.857 for the transvaginal and transperineal measurements, respectively. The coefficient of correlation between the transvaginal and transperineal cervical length measurements was 0.83. TPUS had a sensitivity of 77% in predicting preterm delivery, with a false-positive rate of 17% and a relative risk of 4.5 at the 32.5-mm cutoff value.
  
  
  CONCLUSIONS
  When the cervix is well visualized, TPUS can predict preterm delivery as accurately as TVUS.
authors.affiliation: Department of Gynecology and Obstetrics, Faculty of Medicine, Mersin University, Zeytinlibahce, Mersin, Turkey.
authors.forename: Gurkan
authors.initials: G
authors.lastname: Yazici
authors.forename: Akgun
authors.initials: A
authors.lastname: Yildiz
authors.forename: M Bulent
authors.initials: MB
authors.lastname: Tiras
authors.forename: Murat
authors.initials: M
authors.lastname: Arslan
authors.forename: Arzu
authors.initials: A
authors.lastname: Kanik
authors.forename: Utku
authors.initials: U
authors.lastname: Oz
mesh_terms: D000328:Adult; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011247:Pregnancy; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods*