Open AccessFetal Blood Velocity Waveforms In Normal Pregnancies
Author(s) -
Åström Kjell,
Eliasson Arne,
Hareide Jens H.,
Maršal Karel
Publication year - 1989
Publication title -
acta obstetricia et gynecologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.401
H-Index - 102
eISSN - 1600-0412
pISSN - 0001-6349
DOI - 10.3109/00016348909009907
Subject(s) - umbilical artery , medicine , middle cerebral artery , gestation , fetus , gestational age , cardiology , descending aorta , cerebral arteries , blood flow , aorta , diastole , vascular resistance , hemodynamics , pregnancy , anatomy , blood pressure , ischemia , biology , genetics
Blood velocity in the umbilical artery, fetal descending aorta and fetal middle cerebral artery was recorded by means of 3.5 MHz pulsed Doppler ultrasound in 22 normal pregnancies. The measurements were performed longitudinally between 25 and 42 weeks of gestation. The maximum blood velocity curves were analysed for pulsatility index (PI), systolic/diastolic velocity ratio (S/D ratio) and in the middle cerebral artery also for the resistance index according to Pourcelot (RI). In the umbilical artery, all variables decreased significantly with increasing gestational age as an expression of the decreasing placental vascular resistance. PI in the descending aorta remained fairly constant during the examined period of gestation. In the middle cerebral artery, all three variables (PI, S/D ratio, RI) decreased significantly as gestation advanced. With the exception of the umbilical artery at 28–32 weeks, PI and S/D ratio were not influenced by the heart rate in any of the vessels examined. Diagrams of the gestational age‐related reference values (means 2 SD) for the variables of the blood velocity waveforms were established. Additionally, a ratio of the PI and S/D was calculated for the umbilical artery and middle cerebral artery.