Maternal and cord blood hemostasis at delivery

Comparison of standard and global hemostasis assays in cord and peripheral blood of newborns

BACKGROUND

Umbilical cord blood is used for the testing of various parameters in newborns. However, data on its applicability for hemostasis assays is insufficient.

OBJECTIVE

To evaluate whether umbilical cord blood can be used for standard tests, thromboelastometry and thrombodynamics for preterm and term newborns.

METHODS

187 newborns were included in the study. Blood was taken from the umbilical cord and by venipuncture of the newborn. Clotting times, fibrinogen, D-dimer, thromboelastometry and thrombodynamics were measured.

RESULTS

Clotting times and fibrinogen indicated a hypocoagulable shift, while thromboelastometry and thrombodynamics showed a hypercoagulable shift in hemostasis in umbilical cord blood compared to newborn blood. D-dimer indicated an enhanced process of thrombus lysis in newborn blood compared to cord blood. Collecting blood into a tube with the addition of a contact pathway inhibitor did not significantly change the global assay parameters in either umbilical cord blood or newborn blood. In the thrombodynamics assay, spontaneous clotting was detected but suppressed by the addition of a tissue factor inhibitor.

CONCLUSIONS

Hemostasis in cord and newborn blood differs for both global and standard tests. Hypercoagulability in newborns registered with the global assay thrombodynamics is associated with the presence of tissue factor in the blood.

IMPACT STATEMENT

1. We found a hypercoagulation shift in newborns compared with the adult references, possibly due to the presence of tissue factor in blood. 2. Blood coagulation is enhanced in cord blood compared with blood sampled from the vein of a newborn according to thromboelastometry and thrombodynamics assays. 3. Clotting times and fibrinogen concentrations in cord blood differ from these parameters in newborn blood. 4. Studying of the (patho)physiological features of hemostasis in newborns should consider differences in cord blood and vein sampled blood.

Coagulation and Fibrinolysis in Preeclampsia and Neonates

Coagulation and fibrinolysis were determined in 67 Indonesian women admitted to the University Hospitals for delivery in Medan. They were diagnosed to be at term gestation (mean 39.3 ± 1.1 weeks) with moderate and severe preeclampsia (n=32) and in labor, and 8 had preterm labor (gestation mean 33.5 ± 2.6 weeks). Twenty-seven normal pregnant women in labor (gestation mean 39.7 ± 1.0 weeks) served as controls. Cord blood from 23 neonates from normal pregnancy and 31 neonates from preeclampsia was also evaluated. Preeclamptic women in labor showed further enhanced coagulation activation (F1+2) with raised urokinase-like plasminogen activator (u-PA) activity and reduced plasminogen activator inhibitor-2 (PAI-2) levels. In preterm preeclampsia, significantly reduced antithrombin III (ATIII) and PAI-2 levels with further elevated tissue-type PA (t-PA) antigen and plasminogen activator inhibitor-1 (PAI-1) antigen were seen compared to normal pregnancy. These would suggest a state of enhanced thrombin generation with elevated fibrinolytic/inhibitor proteins in preterm preeclampsia. The reduced PAI-2 levels seen in preeclampsia have been suggested to be associated with reduced placental function. Neonates born to mothers of either normal pregnancy or preeclampsia at term showed similar hemostatic changes with reduced fibrinogen, ATIII, t-PA, u-PA antigen, PAI-1 levels, and coagulation activation compared to their respective maternal plasma levels. No significant differences in hemostatic parameters studied between the neonates of both cohorts were seen, and this would suggest that the neonates were protected from the adverse effects of preeclampsia and their hemostatic system was physiologically balanced.

Correlation of rheological parameters in maternal and fetal blood at term

OBJECTIVE

An association between maternal and fetal blood rheology has not yet been investigated nor is it known whether and to what extent fetal blood rheology may be affected by maternal conditions.

METHODS

At delivery, blood was drawn from the cubital vein of 4985 consecutive mothers and from the umbilical cord during birth for determination of blood rheological parameters (erythrocyte aggregation stasis [E0], low shear [E1], plasma viscosity [Pv]) in addition to hemoglobin (Hb) values and hematocrit (Hct).

RESULTS

Maternal and newborn Pv (r = 0.2; p < 0.0001) correlated statistically significant. There was a remarkable correlation between fetal Pv and gestational age (r = 0.197; p < 0.001). Iron supplementation during pregnancy led to increased fetal Hb, Hct as well as E0 and E1 (p < 0.0001), did not have a significant impact on neonatal Pv (p = 0.068). Smoking mothers gave birth to neonates with significantly higher Pv (p = 0.049), E0 (p = 0.016) and E1 (p = 0.013).

CONCLUSIONS

The increase of fetal plasma viscosity at advanced delivery time-points refers to a more gaining protein synthesis by the fetal liver and thus maturity of the fetus. Iron supplementation as well as smoking during pregnancy is associated with a relative hyper-viscosity in the fetus at delivery.

Procoagulants and anticoagulants in fetal blood. A literature survey

In intrauterine life, hemostasis is maintained by the same components as in extrauterine life (blood platelets, coagulation and fibrinolysis systems, involvement of the vascular wall); in the fetus, however, these components show significant differences of a quantitative/qualitative nature. In the present study, we surveyed the literature on the coagulation system in the fetus. We focused on the velocity of development of the coagulation system, being reflected in the increased concentration of all procoagulants and anticoagulants (a rise from approximately 20% in the middle of pregnancy to about 60% or more in the period of labor; exceptions: factors V, VIII and XIII which in the labor period reach the adult level) and screening test results (prothrombin time, aPTT - activated prothrombin time, and thrombin time). Reference values were given for the 19-38 weeks of pregnancy and the labor term. Biochemical features of fetal fibrinogen and PIVKA factors were also discussed. The role of activated protein C (APC) in the maintenance of balance between procoagulants and anticoagulants was postulated as well as the role of APC in the formation of thrombin activatable fibrinolysis inhibitor (TAFI).

The influence of age on in vitro plasmin generation in the presence of fibrin monomer

BACKGROUND AND OBJECTIVES

The components of the fibrinolytic system interact to generate plasmin from its zymogen form, plasminogen. At birth, all the components of the fibrinolytic system are present but with differing plasma concentrations. The present study was undertaken to explore the effect of physiological, age-dependent factors of the fibrinolytic system during childhood on the capacity to generate plasmin.

DESIGN AND METHODS

Total plasmin generation was measured in venous plasma from umbilical cords and adults, on plastic and cell surfaces, in the presence of fibrin monomer, Desafib. Plasminogen, its inhibitors alpha2-antiplasmin and plasminogen activator inhibitor type 1, and plasmin-alpha2-antiplasmin complex in the time samples were assayed by enzyme-linked immunosorbent assay. The effect of addition of plasminogen on the plasmin generation in cord plasma and the effect of lipoprotein on adult and cord plasmin generation were measured.

RESULTS

On the surface of human umbilical vein endothelial cells, onset of plasmin generation was earlier (40 min) compared to plastic (60 min) but total plasmin generation was similar on both surfaces. The addition of plasminogen to cord plasma increased plasmin generation. Supplementation of lipoprotein in adult plasma had an inhibitory effect, but there was no significant effect in cord plasma.

INTERPRETATIONS AND CONCLUSIONS

Plasmin generation is reduced in newborn compared to adult plasma. Decreased plasmin generation in cord plasma is likely due to decreased plasminogen concentration. The antifibrinolytic effect of lipoprotein is more pronounced in adults as compared to newborns due to the presence of higher plasminogen concentration.

Prothrombin and intraventricular haemorrhage

In the study by Salonvaara et al., low prothrombin activity in preterm infants was associated with intraventricular haemorrhage (IVH). The interesting research question-do preterm infants who develop IVH have underlying coagulation disturbance?-could not be answered in this study.

CONCLUSION

The association needs further investigation. The role of prothrombin in perinatal brain damage in the development of IVH and of white matter damage has to be further elucidated.

The effect of pre-eclampsia on the levels of coagulation and fibrinolysis factors in umbilical cord blood of newborns

The effect of pre-eclampsia on coagulation and fibrinolysis in newborns is still under investigation. We have evaluated several coagulation and fibrinolysis parameters in umbilical cord blood of 20 newborns from pre-eclamptic women and of 40 newborns from normotensive women with similar gestational age. Additionally, the presence of factor V Leiden and prothrombin G20210A mutation in cord blood has been assessed. Neonates from pre-eclamptic women exhibited significantly lower birth weight (2.48 +/- 0.92 versus 2.88 +/- 0.68 kg, P < 0.05) and were more frequently admitted to the neonatal intensive care unit (45 versus 20%, P < 0.01) as compared with neonates from normotensive women. Cord blood protein C antigen and activated protein C resistance mean levels were slightly higher in the group of neonates from pre-eclamptic mothers. Fibrinogen levels were lower in this group as compared with control newborns (132.17 +/- 46.97 versus 156.08 +/- 49.58 mg%, P < 0.02), and unrelated to birth weight. No significant differences between cases and controls were found in plasminogen activator inhibitor-1 or tissue plasminogen activator cord blood levels. Heterozygous prothrombin 20210A was found in three newborns from normotensive mothers, whereas no factor V Leiden mutation was found in either group. In conclusion, pre-eclampsia seems to have only mild effects on coagulation and fibrinolytic factors in the cord blood of newborns. Since no excess of common polymorphisms predisposing to thrombosis was found in newborns from pre-eclamptic mothers, it is unlikely that the carriership status of these genetic defects of newborns influences the adverse pregnancy/neonatal outcomes.

Prothrombotic risk factors in infants of diabetic mothers

BACKGROUND

Infants of diabetic mothers (IDMs) are at an increased risk for thromboembolic disease. The mechanism(s) to explain this association is unclear. We hypothesized that the pathophysiology of thrombosis in IDMs is multifactorial and likely involves interactions among genetic and acquired factors affecting the procoagulant, anticoagulant and fibrinolytic pathways.

OBJECTIVE

To compare the prevalence of common prothrombotic risk factors in a cohort of IDMs to a matched control group.

PATIENTS/METHODS

Full-term infants born to mothers with diet controlled (A1-IDM) (N=17), insulin requiring diabetes (ID-IDM) (N=20) and healthy term infants (controls) (N=20) matched for mode of delivery had cord blood collected at delivery. Samples were analyzed for the following: factor V Leiden (FVL), prothrombin 20210A (P20210A), methylenetetrahydrofolate reductase C677 T (MTHFR), Factor VIII (FVIII), Protein C (PC), Lipoprotein(a) (Lp(a)) and plasminogen activator inhibitor-1 (PAI-1).

RESULTS

None of the infants had a clinically apparent thrombotic event. IDM mothers and their infants were clinically similar to controls except for a higher prevalence of hypoglycemia (30 vs 0%; p=0.005). There was no significant difference in the prevalence of the common genetic risk factors (FVL, P20210A, MTHFR) FVIII, or PAI-1 levels. Elevated Lp(a) levels were seen more frequently in IDMs than Controls (40 vs 20%) but this difference was not statistically significant. The PC activity (%) was significantly decreased in the IDM group compared to controls, 35+/-12 vs 44+/-9 (p<0.005). A1-IDM had lower PC activity compared to ID-IDM (p=0.05) and controls (p=0.001).

CONCLUSIONS

PC deficiency is likely one mechanism to explain thrombosis in IDMs.

Fresh frozen plasma reduces thrombin formation in newborn infants

BACKGROUND

Newborn infants undergoing intensive care are at risk of bleeding and thrombotic complications. Fresh frozen plasma (FFP) is used in hope of preventing these complications, despite poorly defined effects on the coagulation system and lack of proven clinical efficacy.

OBJECTIVES AND METHODS

We prospectively evaluated coagulopathy and the effect of standardized amount of FFP transfusion (10 mL kg-1 + 4 mL in 2 h) on various coagulation markers in 33 newborn infants during the first 24 h of intensive care.

RESULTS

Increased levels of prothrombin fragment F1+2, thrombin-antithrombin complexes (TAT), and d-dimer were found prior to the transfusion in 97%, 81%, and 100% of the patients, respectively. FFP transfusion was associated with a decrease in F1+2 level in 26/32 (81%) of the patients. The extent of F1+2 decrease correlated with the pretransfusion F1+2 level (R = 0.65, P < 0.0001). The patient series was divided into two groups according to increasing pretransfusional F1+2 level: Group 1 (preFFP F1+2 > or = 2.35 nm, n = 16), Group 2 (F1+2 <2.35 nm, n = 16). In Group 1, F1+2 decreased on average 1.58 nm (P < 0.01) from the baseline during FFP transfusion but no significant change in the level of F1+2 during the transfusion was observed in Group 2. Pretransfusional levels of individual factors or prothrombin time (PT) did not correlate with the FFP-associated decrease in F1+2 level.

CONCLUSIONS

In the patients with the highest pretransfusional thrombin formation, FFP had an acute thrombin-reducing effect. Pretransfusion thrombin generation markers, rather than PT or individual pro- and anticoagulants, may be helpful in identifying the patient who will have measurable coagulational effects induced by FFP.

Circulating tissue factor, tissue factor pathway inhibitor and D-dimer in umbilical cord blood of normal term neonates and adult plasma

The investigation of many hemostatic defects in newborns is restricted by the lack of normal reference values. The coagulation system of the neonate differs in many ways from that of the adult. The present study was designed to compare the concentrations of tissue factor (TF), tissue factor pathway inhibitor (TFPI) and D-dimer (DD) in the umbilical cord blood of healthy newborns and in adult plasma. TF antigen was quantified using an in-house enzyme-linked immunosorbent assay, whereas TFPI and DD levels were measured with commercial kits. The mean TF level in cord blood (mean standard deviation, 183.94 103.63 pg/ml) was significantly higher ( = 0.008) than that in adults (136.64 65.09 pg/ml). Cord blood exhibited enhanced fibrinolysis, as was reflected by a significantly higher level of DD (924.57 733.87 ng/ml, 0.001) than that in adults (45.57 17.21 ng/ml). Conversely, cord blood (30.88 10.16 ng/ml) demonstrated significantly lower ( 0.001) TFPI levels than that in adults (55.77 21.16 ng/ml). However, no significant differences of these three hemostatic markers were noted between both gender groups in newborns and adults. Our findings indicate that an active and dynamic state of hemostasis exists in cord blood, as the fluidity of cord blood remains preserved in the presence of birth injury.

Adsorption of proteins from infant and adult plasma to biomaterial surfaces

The hemostatic mechanism of the newborn is immature. In general, the clotting times in screening tests are prolonged, the coagulation factors are low, and the coagulation inhibitors (with the exception of alpha-2-macroglobulin) are low. Recognizing that many of the proteins present in infant plasma are at low levels, it is of interest to determine if, following exposure to artificial surfaces, the profile of adsorbed proteins is different for infant versus adult plasma. The question of whether differences in protein profiles could lead to differences in thromboembolic episodes associated with the use of central venous catheters (or other blood-contacting devices) in infant versus adult subjects also is relevant. To address these issues, the adsorption of proteins from pooled infant plasma and pooled normal adult plasma to three different polymer surfaces (polyvinyl chloride, PVC; polymethyl methacrylate, PMMA; and polyethylene oxide-modified polyurethane, PEO-PU) was studied using SDS-PAGE and immunoblotting techniques. The total amount of protein adsorbed to each surface also was determined. It was found that the PMMA and PVC surfaces adsorbed considerably more protein than the PEO-PU surface. Furthermore, the amount of protein adsorbed to the PMMA and PVC surfaces from infant plasma was significantly less than that adsorbed from adult plasma. No such difference was seen for the protein-repellent PEO-PU surface. The immunoblot responses of proteins bound to the PMMA and PVC surfaces from infant plasma were, in general, weaker than those bound from adult plasma. It is likely that these differences were due to decreased protein levels in infant plasma.