Antenatal sonographic prediction of twin chorionicity

Young Mi Lee, Jane Cleary-Goldman, Harshwardhan M. Thaker, Lynn L. Simpson

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


Objective: We sought to determine the accuracy of antenatal diagnosis of twin chorionicity at a single tertiary care center and assess the consequences of incorrect diagnoses. Study design: Twins with chorionicity diagnosed by ultrasound ≤24 weeks' gestation were retrospectively reviewed. Chorionicity was assigned by sonographic findings including placental location(s), the lambda and T-signs, and/or fetal gender(s). Postnatal diagnosis was determined by placental histopathologic examination. Medical records of antenatal-postnatal discordant chorionicities were reviewed for adverse sequelae. Results: Chorionicity was correctly assigned antenatally in 392/410 (95.6%) twins. The sensitivity, specificity, and positive and negative predictive values of monochorionicity assessed ≤14 weeks were 89.8%, 99.5%, 97.8%, and 97.5%. Corresponding statistical values for the second trimester were 88.0%, 94.7%, 88.0%, and 94.7%. Two cases of inaccurate antenatal diagnoses affected patient counseling or were associated with adverse clinical outcomes. Conclusion: Antenatal assessment of chorionicity is accurate; however, incorrect diagnoses do occur and can affect reliable patient counseling and management.

Original languageEnglish (US)
Pages (from-to)863-867
Number of pages5
JournalAmerican journal of obstetrics and gynecology
Issue number3
StatePublished - Sep 2006
Externally publishedYes


  • Chorionicity
  • Multiple gestation
  • Prenatal diagnosis
  • Twins
  • Ultrasound

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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