[Studies on the rheological characteristics of fetal blood (author's transl)].

Viscosity of fetal and adult blood was measured and compared. The viscosity was measured with a Contraves viscometer at a low shear rate of 0.535 sec(-1). There was no significant difference in the mean value of viscosity between fetal and adult blood. The viscosity of the adult blood showed the time dependent change when measured at the constant shear rate, but fetal one showed no such change. The mixture of adult plasma and fetal red blood cells (hematocrit: 50%) showed the same rheological characteristics as that of adult. On the contrary the mixture of fetal plasma and adult red blood cells showed the rheological characteristics of fetal blood. When the adult blood was observed under microscope numerous rouleaux of red blood cells were observed. However fetal blood showed numerous dispersed red blood cells and only a few poor rouleaux of red blood cells. It was suggested that the rheological characteristics of fetal blood was due to the fetal plasma which contained lower concentrations of fibrinogen and globulin, and which prevented the red blood cells aggregating to form rouleaux.