Reference ranges and ultrasonographic exposure conditions for pulsed Doppler sonographic studies of the fetal internal carotid artery.
We describe the 5th to 95th percentiles for the resistive index from the fetal internal carotid artery and measurements of (1) scanning time and (2) axial distance between transducer face and the fetal skull during pulsed Doppler examinations. Cerebral resistance peaks at 30 weeks' gestation and declines thereafter. The median duration of pulsed Doppler exposure was 31 seconds (range, 4-80 seconds), and the median transducer-skull distance was 2.2 cm (range, 1.3-6.2 cm). Our data provide reference ranges covering the entire period of fetal viability and help define ultrasonographic exposure conditions during pulsed Doppler examinations of fetal intracranial vessels.
Duggan
P M
PM
Department of Obstetrics and Gynecology National Women's Hospital, Auckland, New Zealand.
McCowan
L M
LM
D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000196:embryology; D005260:Female; D005333:Fetus; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D012016:Reference Values; D016216:Ultrasonography, Prenatal / Q000379:methods*