[Blood flow parameters in fetal anterior cerebral artery during the second and third trimester of gestation].

To investigate hemodynamic parameters in 2 anatomical segments (S1 and S2) of anterior cerebral artery (ACA) in normal pregnancy during the second and third trimester of gestation.
 Methods: The peak systolic velocity (PSV), end diastolic velocity (EDV), time-average maximum velocity (TAMAXV), peak systolic velocity/end diastolic velocity (S/D), resistance index (RI), and pulsation index (PI) in S1 and S2 of fetal anterior cerebral artery (ACA) in 288 normal pregnant women were detected by power Doppler and pulsed Doppler. Multiple regression models were fitted to estimate the relation between Doppler variables and gestational age. The differences of hemodynamic parameters between ACAS1 and ACAS2 were compared.
 Results: The PSV, EDV, and TAMAXV of ACAS1 and ACAS2 were positively correlated with the weeks of pregnancy (P<0.001), all fitted with the cubic curve. The S/D, PI, and RI values of ACAS1 and ACAS2 were not correlated with gestational ages (P>0.05). The PSV, TAMAXV, S/D, PI, and RI of ACAS1 were significantly higher than those of ACAS2, while EDV in ACAS1 was lower than that in ACAS2 (P<0.05).
 Conclusion: The velocity parameters (PSV, EDV, TAMAXV) of the 2 anatomical segments (ACAS1 and ACAS2) are increased with the increase of gestational age in normal pregnant fetus during the second and third trimester of gestation, and the resistance parameters (S/D, PI, RI) are not significantly correlated with gestational age. Distribution of blood flow is different in the blood supply territory between ACAS1 and ACAS2.