Fetal brain sparing is strongly related to the degree of increased placental vascular impedance.
BACKGROUND
Doppler ultrasound examination has become an established method of clinical surveillance in high-risk pregnancies. Doppler indication of fetal brain sparing (BS) is an acknowledged sign of circulation redistribution during chronic hypoxia.


OBJECTIVE
To evaluate the relationship between placental vascular resistance and signs of BS in middle cerebral artery (MCA) blood flow velocity.


METHODS
The MCA, uterine artery, and umbilical artery (UA) were located by color Doppler ultrasound in 103 high-risk pregnancies at risk for intrauterine fetal hypoxia. The blood velocity spectrum was analyzed for the following parameters: pulsatility index (PI) and signs of notching in the uterine arteries. Z-score was calculated for the MCA PI.


RESULTS
Signs of BS in the MCA were correlated to increased placental vascular impedance. The degree of BS in the MCA expressed as Z-scores was correlated to increasing vascular impedance, both in the umbilical and uterine arteries, and to adverse outcome of pregnancy. The greatest deviation in MCA PI Z-scores was seen in preterm pregnancies.


CONCLUSIONS
A clear correlation exists between increasing placental vascular impedance and BS in the MCA. Preterm pregnancies express the greatest deviation from the mean MCA PI.
Cheema
Riffat
R
Department of Obstetrics and Gynecology, Malmö University Hospital, Malmö, Sweden.
Dubiel
Mariusz
M
Gudmundsson
Saemundur
S
D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D005311:Fetal Hypoxia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005333:Fetus / Q000098:blood supply*; D006801:Humans; D007231:Infant, Newborn; D021041:Placental Circulation / Q000502:physiology*; D011247:Pregnancy; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000503:physiopathology; D014599:Uterus / Q000098:blood supply / Q000000981:diagnostic imaging; D014655:Vascular Resistance / Q000502:physiology*