Red cell aggregation during normal pregnancy

Abstract

Red cell aggregation (RCA) is responsible for the increase in whole blood viscosity at lower shear rates. RCA depends on the concentrations of red cells and plasma proteins with a high molecular weight and a large and asymmetrical spatial structure such as fibrinogen, immunoglobulin M and alpha 2-macroglobulin. During normal pregnancy, changes occur in all these concentrations. In a prospective study these changes and their influence on the resulting RCA were investigated in 24 healthy women with normal pregnancies. RCA was determined by light reflection measurement (syllectometry). RCA considerably increased during normal pregnancy in spite of the physiological haemodilution. The aggregation half time, used as a measure for RCA, decreased from an average non-pregnant value of 5.6 s to 3.3 s at 37 weeks. Multiple regression analysis showed that the increase in RCA could be mainly attributed to the raised fibrinogen concentration. However, at 37 weeks other factors, in addition to fibrinogen, contribute significantly to the increase in RCA.

Evaluation Haematological Parameters among Pregnant Women Attending Antenatal Clinic in College Of Health Demonstration Clinic, Port Harcourt

“…Vanden-Broek and Letsky (2008), also recorded a decrease in PCV from 36-20% in all the trimesters due to systemic vascular resistance (SVR) level of hormones. The decreasing SVR is an expected result of the increasing progesterone and prostaglandin levels, which relax smooth muscle producing vasodilation and also Huisman et al, (2008) also stated that stages of pregnancy affect PCV which also agrees with this finding.…”

The influence of maternal erythrocyte deformability on fetal growth, gestational age and birthweight

“…As demonstrated in table 2, increases in the globulins (mainly alpha2-globulins) and the decrease in the albumin/globuline ratio (Alb/globulins) as well as being associated with lower erythrocyte deformability, reinforces the attraction between cells and erythrocyte aggregation capability [8,40], especially in areas of low velocity blood flow, such as the intervillous space [16,17]. As demonstrated in table 2, increases in the globulins (mainly alpha2-globulins) and the decrease in the albumin/globuline ratio (Alb/globulins) as well as being associated with lower erythrocyte deformability, reinforces the attraction between cells and erythrocyte aggregation capability [8,40], especially in areas of low velocity blood flow, such as the intervillous space [16,17].…”

Pregnancy at high altitude: a hyperviscosity state

“…In normal pregnancy, the reduced hematocrit (as a result of the larger plasma volume expansion compared to the increase in red cell mass) is a compensatory mechanism for the enhanced red cell aggregation and plasma viscosity and a means of reducing intervillous resistance to blood flow (53). Resistance to blood flow is strongly hematocrit dependent and the higher the resistance the lower the rate of perfusion for a given pressure (54).…”