[Hemorrheological parameters during normal labor and uterine contraction].Rev Fr Gynecol Obstet 1991; 86(2 Pt 2):148-53RF
Considering the modified fluidity of blood during numerous kind of stress, the authors studied blood rheology during delivery as an example of a particularly severe stress. The authors measured blood and plasma viscosity and erythrocyte aggregation in 77 pregnant at the following stages of delivery: below 4 cm dilatation; more than 4 cm dilatation; during fetus expulsion, during after birth delivery. Apparent blood viscosity and viscosity adjusted to 45% hematocrit rose to reach a peak during expulsion (p less than 0.01) then to become normal again during placenta delivery (p less than 0.01). Hematocrit and plasmatic viscosity showed no changes during labour and expulsion. In addition erythrocyte aggregation was lowering during expulsion and delivery (stage with physiological defibrination). Rising blood viscosity might be explained by a red blood cell rigidification measured by the increasing of "Tk" (p less than 0.01) and by a nonsignificant increase of the filterability index measured by hemorheometer. In conclusion, delivery is accompanied by a blood hyperviscosity essentially related to a transient red blood cell rigidification.