First trimester ultrasound screening for fetal aneuploidy and middle cerebral artery Doppler assessment for fetal alloimmunization.
OBJECTIVE
Traditional methods of fetal evaluation require invasive procedures (e.g. amniocentesis) with an inherent, albeit low, risk of complications and pregnancy loss. As medical knowledge and ultrasound technology have advanced, noninvasive modes of fetal evaluation have become increasingly used. Two disorders in which this has been most applied are fetal aneuploidy and alloimmunization to red blood cell antigens.


RESULTS
First-trimester screening protocols for fetal aneuploidy combine ultrasound measurement of the fetal nuchal translucency with the measurement of two maternal serum hormones, free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A. This combination detects approximately 85% of women pregnant with fetuses with trisomy 21. An increase in the velocity of fetal middle cerebral artery blood flow occurs in the setting of moderate to severe fetal anemia and can be measured with Doppler ultrasound. Middle cerebral artery evaluation is equally sensitive in the prediction of anemia as amniocentesis for bilirubin breakdown products and has less associated risk. It has an additional benefit because it can also be applied to causes of anemia other than hemolysis.


CONCLUSIONS
Noninvasive methods of fetal assessment are becoming increasingly commonplace. There has been a dramatic decrease in the use of prenatal diagnostic services as screening strategies have become available. Doppler assessment of the velocity of blood flow through the fetal middle cerebral artery will allow for more judicious application of invasive procedures to pregnancies at significant risk for anemia.
Biggio
Joseph R
JR
Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine and Reproductive Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA. jbiggio@uab.edu
D000782:Aneuploidy; D002648:Child; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000235:genetics / Q000517:prevention & control; D005820:Genetic Testing; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000196:embryology; D048208:Nuchal Translucency Measurement / Q000379:methods; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods*; D012203:Rh Isoimmunization / Q000175:diagnosis* / Q000517:prevention & control