Accuracy of sonographic chorionicity classification in twin gestations

Yair J. Blumenfeld*, Valerija Momirova, Dwight J. Rouse, Steve N. Caritis, Anthony Sciscione, Alan M. Peaceman, Uma M. Reddy, Michael W. Varner, Fergal D. Malone, Jay D. Iams, Brian M. Mercer, John M. Thorp, Yoram Sorokin, Marshall W. Carpenter, Julie Lo, Susan M. Ramin, Margaret Harper

*Corresponding author for this work

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Objectives - To evaluate the accuracy of sonographic classification of chorionicity in a large cohort of twins and investigate which factors may be associated with sonographic accuracy. Methods - We conducted a secondary analysis of a randomized trial of preterm birth prevention in twins. Sonographic classification of chorionicity was compared with pathologic examination of the placenta. Maternal (age, body mass index, diabetes, and hypertension), obstetric (prior cesarean delivery, gestational age at the first sonographic examination, and antepartum bleeding), and sonographic (oligohydramnios, polyhydramnios, and twin-twin transfusion syndrome) factors were assessed for their possible association with accuracy. Results - A total of 545 twin sets in which chorionicity was classified by sonography before 20 weeks' gestation were included; 455 were dichorionic and 90 were monochorionic based on pathologic examination. Sonography misclassified 35 of 545 twin pregnancies (6.4%): 18 of 455 dichorionic twins (4.0%) and 17 of 90 monochorionic twins (19.0%). The sensitivity and specificity of sonographic diagnosis of monochorionicity were 81.1% and 96.0%, respectively. In a multivariable analysis, pregnancies with initial sonographic examinations before 14 weeks' gestation were less likely to have misclassified chorionicity than those with sonographic examinations at 15 to 20 weeks (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.23-0.96). For each week increase in gestational age, the odds of misclassification rose by 10% (OR, 1.10; 95% CI, 1.01-1.2). In the multivariable analysis, maternal age, body mass index, parity, and prior cesarean delivery were not associated with sonographic accuracy. Conclusions - Sonography before 20 weeks incorrectly classified chorionicity in 6.4% of twin gestations. Those with first sonographic examinations performed at earlier gestational ages had improved chorionicity diagnosis.

Original languageEnglish (US)
Pages (from-to)2187-2192
Number of pages6
JournalJournal of Ultrasound in Medicine
Volume33
Issue number12
DOIs
StatePublished - Dec 1 2014

Keywords

  • Accuracy
  • Chorionicity
  • Obstetric ultrasound
  • Sonography
  • Twins

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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  • Cite this

    Blumenfeld, Y. J., Momirova, V., Rouse, D. J., Caritis, S. N., Sciscione, A., Peaceman, A. M., Reddy, U. M., Varner, M. W., Malone, F. D., Iams, J. D., Mercer, B. M., Thorp, J. M., Sorokin, Y., Carpenter, M. W., Lo, J., Ramin, S. M., & Harper, M. (2014). Accuracy of sonographic chorionicity classification in twin gestations. Journal of Ultrasound in Medicine, 33(12), 2187-2192. https://doi.org/10.7863/ultra.33.12.2187