Detection of fetal structural abnormalities with US during early pregnancy.
Ultrasonography (US) is performed during early pregnancy for dating, determination of the number of fetuses, assessment of early complications, and increasingly for evaluation of the fetus, including measurement of the thickness of the nuchal translucency (NT). Measurement of NT thickness between 11 and 14 weeks gestation, combined with maternal age and maternal serum biochemistry, can be an effective method of screening for trisomy 21 and other chromosomal abnormalities. Furthermore, an increased NT thickness in the presence of a normal karyotype is associated with an increased frequency of structural defects and genetic syndromes. Therefore, this finding is an indication for a more detailed anatomic survey of the fetus. Besides nuchal abnormalities, a wide range of other congenital anomalies can be diagnosed with US at 11-14 weeks gestation, including defects of the central nervous system, heart, anterior abdominal wall, urinary tract, and skeleton. The anatomic survey can be performed with a standardized protocol by using transabdominal US and, when necessary, transvaginal US. A thorough knowledge of the US features of normal fetal development is necessary to avoid potential diagnostic pitfalls.
Fong
Katherine W
KW
Department of Medical Imaging, Mount Sinai Hospital and University of Toronto, 600 University Ave, Rm 570, Toronto, ON, Canada M5G 1X5. katherine.fong@sympatico.ca
Toi
Ants
A
Salem
Shia
S
Hornberger
Lisa K
LK
Chitayat
David
D
Keating
Sarah J
SJ
McAuliffe
Fionnuala
F
Johnson
Jo-Ann
JA
D034861:Abdominal Wall / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000196:embryology; D000015:Abnormalities, Multiple / Q000000981:diagnostic imaging* / Q000196:embryology*; D001842:Bone and Bones / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000196:embryology; D001921:Brain / Q000002:abnormalities; D004200:Diseases in Twins / Q000175:diagnosis; D004452:Echocardiography; D005260:Female; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging / Q000196:embryology; D006801:Humans; D006828:Hydatidiform Mole / Q000000981:diagnostic imaging / Q000196:embryology; D009295:Nasal Bone / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000196:embryology; D009436:Neural Tube Defects / Q000000981:diagnostic imaging; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014551:Urinary Tract / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000196:embryology