Unfused amnion and chorion after 14 weeks of gestation: associated fetal structural and chromosomal abnormalities.
OBJECTIVE
To assess possible associations between delayed chorioamniotic fusion after the end of the first trimester and fetal structural and/or chromosomal abnormalities.


METHODS
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.
Ulm
B
B
Department of Obstetrics and Gynecology, University Hospital of Vienna, Austria.
Ulm
M R
MR
Bernaschek
G
G
D000650:Amnion / Q000000981:diagnostic imaging / Q000502:physiology*; D002823:Chorion / Q000000981:diagnostic imaging / Q000502:physiology*; D002869:Chromosome Aberrations; D025063:Chromosome Disorders / Q000000981:diagnostic imaging*; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D006801:Humans; D007621:Karyotyping; D010865:Pilot Projects; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018566:Pregnancy, High-Risk; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal