Haemostatic and rheological changes in normal pregnancy and pre‐eclampsia

Abstract

Platelet activity (microaggregate formation, ADP-aggregation and beta-thromboglobulin release), coagulation activity (fibrinogen level and factor VIII related antigen/coagulant activity), and rheological factors (plasma viscosity, whole-blood viscosity and erythrocyte deformability) were studied serially in 14 healthy pregnancies to determine the effect of gestational age. Fourteen patients with pre-eclampsia, each matched for stage of gestation with a normal pregnancy, showed normal rheology of circulating blood and normal aggregability of circulating platelets, but there was a significant increase in platelet release of beta-thromboglobulin and a shorter platelet production time, indicating a shorter life-span. The results suggest that localized platelet activation within the utero-placental microvasculature, rather than a rheological abnormality, is a likely contributory factor to the occlusive vascular lesion of pre-eclampsia and fetal growth retardation.

Hemostasis in Pregnant Saudi Women

“…Some investigators found increased aggregability to ADP and adrenaline during pregnancy. 21,27,41 Our results disagree with these observations, since the aggregation responses to ADP, adrenaline, arachidonic acid, collagen, and ristocetin were significantly lower during pregnancy compared to nonpregnant controls. In contrast, other investigators could not establish any differences between pregnant and nonpregnant women.…”

“…Reports on platelet count in pregnancy have provided discordant results. In most studies, no significant changes were observed, 11,15,21,26,27 while in others, like our own, a slight reduction was found. 15,28,29 In contrast to these findings, Mor et al 30 found a marked and progressive increase in the platelet count during pregnancy and a sharp drop at the time of placental delivery.…”

“…16 We also noted a progressive rise in factor VIII activities (factor VIII:C, ristocetin cofactor, and vWFAg), especially in the second and third trimesters, and this agrees with findings from earlier reports. 11,15,[17][18][19][20][21] In the present study, the vWFAg/VIII:C ratios in the first, second, and third trimesters are 1.23, 1.7, and 1.6, respectively. Such elevated ratios are common in normal pregnancy 14,22,23 and are indicative of thrombin-induced loss of factor VIII:C activity as a consequence of activation of the coagulation system and thrombin generation.…”

Fibrinogen: A Treatable Risk Factor?

“…Plasma levels of fibrinogen are related to physiological factors: race [13], gender [14], age [15], pregnancy [16], menopause [17], to lifestyle and environmental factors: smoking [18], body weight [19], stress [20], social class [21], alcohol intake, exercise [22], season [23] and to pathological conditions, mainly inflammatory status. The genetic contribution to the plasma level of fibrinogen is estimated to range between 20 [24] the consequence of an acute-phase reaction, whereas oth er proteins like C-reactive protein can increase more than hundred-fold under similar cytokine stimulation (IL-6, IL-ip, TNF-a) [27,28].…”

Hemorrheological Approach to Thrombotic Microangiopathies

“…Many situations have recently proven to be associated with the presence of inelastic, only slightly deformable 'dangerous red cells', through still undefined alterations in the relationship between the membrane structures or in the intracytoplasmatic constituents: preeclampsia [85][86][87], hypertension [88][89][90][91], diabetes [92][93][94][95], hyperlipi demia [96,97], hyperfibrinogenemia [79,96], hyposideremia [98], vitamin E deficiency [99], and acidosis [100].…”