Crane, J M Transvaginal ultrasound in the prediction of preterm delivery: singleton and twin gestations. [electronic resource] - Obstetrics and gynecology Sep 1997 - 357-63 p. digital Publication Type: Clinical Trial; Comparative Study; Journal Article ISSN: 0029-7844 Standard No.: 10.1016/s0029-7844(97)00277-9 doi Subjects--Topical Terms: AdultFemaleHumansObstetric Labor, Premature--diagnostic imagingPredictive Value of TestsPregnancyPregnancy, MultipleROC CurveSensitivity and SpecificityUltrasonography, Prenatal--methodsVagina