Blood flow in the intervillous space and fetal blood flow

Assessment of umbilical arterial and venous flow using color Doppler

“…Xenon radioisotope injection into the intervillous space can be a major source of error through incorrect injection technique or placental heterogeneity 1 . This work departs from previous studies in that we combined blood flow measurements for both the arteries and vein in the same umbilical cord to give an estimation of average flow.…”

“…Several authors have attempted to quantify umbilical venous blood flow using invasive in utero isotope injections 1 and ex utero thermodilution methods 2,3 . From the early 1980s onwards, the combination of B-mode ultrasonography and pulsed Doppler has been used to measure intra-abdominal umbilical venous flow [4][5][6][7] , although its use has not gained widespread acceptance in obstetric sonography.…”

Washout of Xenon-133 from Isolated Guinea-Pig Placenta

“…Conditions will probably be worse when a human placenta in situ is to be investigated. Thus we think it not justified to regard the 'fast' component as representative of the intervillous blood flow [Clavero et al, 1973;Husemeyer and Crawley, 1979;Rekonen et al, 1976], The 'slow' component also cannot be associated uniquely with myometrial [Husemeyer and Crawley, 1979;Rekonen et al, 1976] or fetal placental [Cla vero et al, 1973] blood flow. The failure is mostly due to the knowledge that clearance curves, at least of the isolated guinea-pig pla centa preparation, cannot be regarded as sums of monoexponentials.…”

Blood flow measurements in the fetal descending aorta: Technique and Clinics

“…Techniques used in these studies and others, for example, clearance rates measurements (Clavero et al, 1973;Gant er al., 1976), postabortion (Assali et al, 1969) and postdelivery measurements (McCallum, 1977a, b;Stembera et al, 1968) were invasive and introduced nonphysiological conditions that would certainly have influenced results.…”