Unfused amnion and chorion after 14 weeks of gestation: associated fetal structural and chromosomal abnormalities

Ultrasound Obstet Gynecol. 1999 Jun;13(6):392-5. doi: 10.1046/j.1469-0705.1999.13060392.x.

Abstract

Objective: To assess possible associations between delayed chorioamniotic fusion after the end of the first trimester and fetal structural and/or chromosomal abnormalities.

Design: We prospectively studied 492 fetuses from high-risk pregnancies between 14 and 18 weeks of gestation by transabdominal ultrasonography. Of these, 60 (12%) had unfused amnion and chorion.

Results: No additional abnormalities were detected in 28/60 fetuses (47%). Karyotyping was performed in 27/28 cases, and one fetus had trisomy 13 (4%). Ten of 24 fetuses (42%) of this group attending a second mid-trimester scan after 18 weeks of gestation had abnormal sonographic findings not noted at the initial scan. Thirty-two of 60 (53%) fetuses had additional abnormalities at the initial scan: cystic hygroma (n = 12), increased nuchal translucency (n = 10) and other abnormalities (n = 10). Karyotyping revealed aneuploidy in 13 of 28 fetuses (46%) tested: trisomy 21 (n = 5), Turner's syndrome (n = 3), trisomy 18 (n = 3) and trisomy 13 (n = 2). Additional fetal abnormalities were detected only at the second scan after 18 weeks of gestation in three of eight fetuses (38%).

Conclusions: These preliminary data suggest that the sonographic finding of unfused amnion and chorion after 14 weeks of gestation may be associated with fetal structural and/or chromosomal abnormalities.

Publication types

  • Comment

MeSH terms

  • Amnion / diagnostic imaging
  • Amnion / physiology*
  • Chorion / diagnostic imaging
  • Chorion / physiology*
  • Chromosome Aberrations*
  • Chromosome Disorders / diagnostic imaging*
  • Female
  • Fetal Diseases / diagnostic imaging*
  • Humans
  • Karyotyping
  • Pilot Projects
  • Pregnancy
  • Pregnancy Trimester, First
  • Pregnancy, High-Risk*
  • Prospective Studies
  • Ultrasonography, Prenatal*