Prenatal ultrasonographic assessment of the middle cerebral artery: a review.

Published reports, case studies, and articles regarding ultrasonographic morphology, physiology, and pathophysiology of the fetal middle cerebral artery obtained from a MEDLINE search from 1966 through January 1997 were reviewed. Both transabdominal and transvaginal color Doppler ultrasonographic modalities may be used to assess fetal middle cerebral artery flow hemodynamics. Altered middle cerebral artery flow velocities may be noted in various medical conditions that include various behavioral states, term and preterm labor, maternal medications (anesthesia, tocolytics), fetal compromise (growth restriction and hypoxia), twin-twin transfusion syndrome, invasive diagnostic procedures (amniocentesis and fetal blood sampling), fetal anemia and transfusion, in addition to intracranial fetal lesions (congenital anomalies and hemorrhage). In summary, knowledge of Doppler flow velocity of the fetal middle cerebral artery may assist prenatal diagnosis and management of complicated pregnancies.