Thrombin-antithrombin III complex levels in normal pregnancy with hypertensive disorders and after delivery

DIC in Pregnancy - Pathophysiology, Clinical Characteristics, Diagnostic Scores, and Treatments

Obstetrical hemorrhage and especially DIC (disseminated intravascular coagulation) is a leading cause for maternal mortality across the globe, often secondary to underlying maternal and/or fetal complications including placental abruption, amniotic fluid embolism, HELLP syndrome (hemolysis, elevated liver enzymes and low platelets), retained stillbirth and acute fatty liver of pregnancy. Various obstetrical disorders can present with DIC as a complication; thus, increased awareness is key to diagnosing the condition. DIC patients can present to clinicians who may not be experienced in a variety of aspects of thrombosis and hemostasis. Hence, DIC diagnosis is often only entertained when the patient already developed uncontrollable bleeding or multi-organ failure, all of which represent unsalvageable scenarios. Beyond the clinical presentations, the main issue with DIC diagnosis is in relation to coagulation test abnormalities. It is widely believed that in DIC, patients will have prolonged prothrombin time (PT) and partial thromboplastin time (PTT), thrombocytopenia, low fibrinogen, and raised D-dimers. Diagnosis of DIC can be elusive during pregnancy and requires vigilance and knowledge of the physiologic changes during pregnancy. It can be facilitated by using a pregnancy specific DIC score including three components: 1) fibrinogen concentrations; 2) the PT difference - relating to the difference in PT result between the patient's plasma and the laboratory control; and 3) platelet count. At a cutoff of ≥26 points, the pregnancy specific DIC score has 88% sensitivity, 96% specificity, a positive likelihood ratio (LR) of 22, and a negative LR of 0.125. Management of DIC during pregnancy requires a prompt attention to the underlying condition leading to this complication, including the delivery of the patient, and correction of the hemostatic problem that can be guided by point of care testing adjusted for pregnancy.

Nonovert disseminated intravascular coagulation (DIC) in pregnancy: a new scoring system for the identification of patients at risk for obstetrical hemorrhage requiring blood product transfusion

BACKGROUND

Nonovert disseminated intravascular coagulation (DIC) is a subclinical hemostatic dysfunction that has not yet reached the decompensation stage. The detection of pregnant patients at this stage may assist in the identification of those who will develop severe obstetrical hemorrhage, as it is one of the leading causes for preventable maternal mortality. Currently, nonovert DIC is diagnosed by a scoring system based on nonpregnant patients, originally generated by the International Society on Thrombosis and Hemostasis (ISTH), which does not address the physiologic changes of the hemostatic system during pregnancy.

OBJECTIVES

(1) To develop a pregnancy-specific nonovert DIC score, (2) to determine the diagnostic performance of this score in detecting women at risk for obstetrical hemorrhage requiring blood product transfusion, and (3) to compare it to the existing ISTH nonovert DIC score.

STUDY DESIGN

This retrospective study has longitudinal and cross-sectional components and includes three steps: (1) characterization of the longitudinal changes in the components of modified ISTH nonovert DIC scores, including these parameters - fibrinogen, antithrombin III, protein C, prothrombin time (PT), platelets, thrombin-antithrombin (TAT) complex, and D-dimer - during gestation in a group of normal pregnancies (n = 50); (2) development of a pregnancy-specific nonovert DIC score in a cross-sectional design of high-risk (n = 152) and control (n = 50) pregnancies, based on the predictive performance of each analyte for the detection of women at risk for obstetrical hemorrhage requiring blood product transfusion and a logistic regression model; and (3) comparison between the diagnostic performance of the pregnancy-specific nonovert DIC score and the modified ISTH nonovert DIC score to detect, upon admission, women who are at increased risk for subsequent development of obstetrical hemorrhage requiring blood product transfusion.

RESULTS

(1) The study cohort included 202 patients, of which 21 (10%) had obstetrical hemorrhage that required blood product transfusion and were considered to have nonovert DIC; (2) using the nonpregnant ISTH nonovert DIC score, 92% of the patients had a D-dimer concentration above the 0.5 mg/L threshold, and only 2% were identified to have a low fibrinogen concentration (<100 mg/dL); thus, this scoring system was unable to identify any of the patients with nonovert DIC based on the suggested cutoff of a score of ≥5; (3) the parameters included in the pregnancy-specific nonovert DIC score were selected based on their contribution to the performance of the model for the prediction of women at risk for obstetrical hemorrhage requiring blood product transfusion; as a result, we excluded the PT difference parameter from the score and the TAT complex concentration was added; and (4) a pregnancy-specific nonovert DIC score of ≥3 had a sensitivity of 71.4% and a specificity of 77.9% to identify patients at risk for obstetrical hemorrhage requiring blood product transfusion.

CONCLUSION

We propose (1) a pregnancy-specific nonovert DIC score adjusted for the physiologic changes in the hemostatic system during gestation; and (2) that the pregnancy-specific nonovert DIC score can be a useful tool for the identification of patients at risk for obstetrical hemorrhage requiring blood product transfusion.

The pattern and magnitude of "in vivo thrombin generation" differ in women with preeclampsia and in those with SGA fetuses without preeclampsia

OBJECTIVE

We aimed to determine the differences in the pattern and magnitude of thrombin generation between patients with preeclampsia (PE) and those with a small-for-gestational-age (SGA) fetus.

METHODS

This cross-sectional study included women in the following groups: (1) normal pregnancy (NP) (n = 49); (2) PE (n = 56); and (3) SGA (n = 28). Maternal plasma thrombin generation (TGA) was measured, calculating: (a) lag time (LT); (b) velocity index (VI); (c) peak thrombin concentration (PTC); (d) time-to-peak thrombin concentration (TPTC); and (e) endogenous thrombin potential (ETP).

RESULTS

(1) The median TPTC, VI, and ETP differed among the groups (p = .001, p = .006, p < .0001); 2) the median ETP was higher in the PE than in the NP (p < .0001) and SGA (p = .02) groups; 3) patients with SGA had a shorter median TPTC and a higher median VI than the NP (p = .002, p = .012) and PE (p < .0001, p = .006) groups.

CONCLUSIONS

(1) Patients with PE had higher in vivo thrombin generation than women with NP and those with an SGA fetus; (2) the difference in TGA patterns between PE and SGA suggests that the latter group had faster TGA, while patients with PE had a longer reaction, generating more thrombin. This observation is important for the identification of a subset of patients who might benefit from low molecular-weight heparin.

Blood laboratory testing for early prediction of preeclampsia: chasing the finish line or at the starting blocks?

Preeclampsia (PE) affects 2-8% of pregnancies worldwide, thus representing an important cause of maternal and neonatal morbidity, up to death. Many studies have been designed to identify putative biomarkers for accurate and timely diagnosing PE, but only some of them were focused on specific and sensitive biomarkers for early prediction of this life-threatening condition. In particular, some prospective studies aimed to investigate the predictive role of circulating biomarkers before 20 weeks of gestation in the general pregnant population yielded conflicting results. This article is hence centered on results obtained in studies investigating the predictive performances of angiogenic, anti-angiogenic, inflammatory, endocrine, and epigenetic biomarkers. The available evidence suggests that angiogenic and anti-angiogenic molecules, in particular the sFlt1:PlGF ratio, may be considered the biomarkers with the best diagnostic performance in the second trimester. However, doubts remain about their use in clinical settings before the 20th gestational week. Even lower evidence is available for other biomarkers, due to the fact that some positive results have not been confirmed in ensuing investigations, whereas unresolved analytical issues still contribute to make their clinical reliability rather questionable. Differential expression of microRNAs seems also a promising evidence for early prediction of PE, but additional research and well-designed prospective studies are needed to identify and validate routine predictive tests. KEY MESSAGES Preeclampsia affects 2-8% of pregnant women worldwide, thus remaining one of the leading causes of maternal and neonatal morbidity and mortality. Several studies have investigated the predictive role of circulating biomarkers before 20th week of gestation with conflicting results. Additional research and well-designed prospective studies are needed to identify and validate predictive tests in clinical practice.

Placental vascular pathology and increased thrombin generation as mechanisms of disease in obstetrical syndromes

Obstetrical complications including preeclampsia, fetal growth restriction, preterm labor, preterm prelabor rupture of membranes and fetal demise are all the clinical endpoint of several underlying mechanisms (i.e., infection, inflammation, thrombosis, endocrine disorder, immunologic rejection, genetic, and environmental), therefore, they may be regarded as syndromes. Placental vascular pathology and increased thrombin generation were reported in all of these obstetrical syndromes. Moreover, elevated concentrations of thrombin-anti thrombin III complexes and changes in the coagulation as well as anticoagulation factors can be detected in the maternal circulation prior to the clinical development of the disease in some of these syndromes. In this review, we will assess the changes in the hemostatic system during normal and complicated pregnancy in maternal blood, maternal–fetal interface and amniotic fluid, and describe the contribution of thrombosis and vascular pathology to the development of the great obstetrical syndromes.

HELLP syndrome in pregnancies below 26th week

OBJECTIVE

To test the hypothesis that HELLP syndrome may be more likely to develop earlier, if a pregnant woman has aPL antibodies, and to observe clinical and laboratory factors preceding the occurrence of HELLP syndrome.

MATERIALS AND METHODS

The study consisted in retrospective analysis, with updated verification, of HELLP syndrome in pregnancies below 26th week in our clinic in the years 1992-2010.

RESULTS

HELLP syndrome, if it occurred before the 26th week, occurred only in women with preeclampsia superimposed on chronic hypertension and in women with aPL antibodies. HELLP syndrome with aPL antibodies occurred with low level of platelets (mean 35.5 × 10(9)/L), lower level of AT III (mean 71.3%), lymphopenia, higher CRP (mean 9.1) and pale infarct of placenta (100%). The occurrence of HELLP syndrome was always preceded by surges in blood pressure resistant to antihypertensive drugs.

CONCLUSION

HELLP syndrome in early pregnancy may indicate the presence of aPL antibodies. It may also be a clinical symptom of APS. A surge in blood pressure is a clinical forerunner of the coming HELLP syndrome. HELLP syndrome in women with APS is characterized by low level of platelets.

Leukocytes of pregnant women with small-for-gestational age neonates have a different phenotypic and metabolic activity from those of women with preeclampsia

OBJECTIVE

Preeclampsia and pregnancies complicated by small-for-gestational age (SGA) neonates share several underlying mechanisms of disease. However, while an exaggerated systemic maternal inflammatory response is regarded as one of the hallmarks of the pathogenesis of preeclampsia, the presence of a similar systemic intra-vascular inflammation in mothers of SGA neonates without hypertension is controversial. The aim of this study was to determine phenotypic and metabolic changes in granulocytes and monocytes of women who develop preeclampsia and those who deliver an SGA neonate, compared to normal pregnant women.

METHODS

This cross-sectional study included patients with a normal pregnancy (n = 33), preeclampsia (n = 33), and an SGA without preeclampsia (n = 33), matched for gestational age at blood sample collection. Granulocyte and monocyte phenotypes were determined by flow cytometry, using monoclonal antibodies against selective cluster of differentiation (CD) antigens. The panel of antibodies included the following: CD11b, CD14, CD16, CD18, CD49d, CD62L, CD64, CD66b, and HLA-DR. Intracellular reactive oxygen species (iROS) were assessed at the basal state and after stimulation (oxidative burst). Results were reported as mean channel brightness (MCB) or intensity of detected fluorescence. Analysis was conducted with non-parametric statistics. A p-value < 0.01 was considered statistically significant.

RESULTS

(1) Women who delivered an SGA neonate had a higher MCB of CD11b in granulocytes and monocytes than those with a normal pregnancy (p < 0.001 for both); (2) patients with preeclampsia had a lower median MCB of CD62L in granulocytes (p = 0.006) and a higher median basal iROS and oxidative burst in monocytes than women with an SGA neonate (p = 0.003 and p = 0.002, respectively).

CONCLUSION

Pregnancies complicated by the delivery of an SGA neonate are characterized by a higher activation of maternal peripheral leukocytes than in normal pregnancies, but lower than in pregnancies complicated by preeclampsia.

Evidence of maternal platelet activation, excessive thrombin generation, and high amniotic fluid tissue factor immunoreactivity and functional activity in patients with fetal death

OBJECTIVE

Fetal death can lead to disseminated intravascular coagulation or fetal death syndrome. However, currently it is not clear what are the changes in the coagulation system in patients with a fetal death without the fetal death syndrome. This study was undertaken to determine: (1) whether fetal death in the absence of fetal death syndrome is associated with changes in hemostatic markers in maternal plasma and amniotic fluid; and (2) whether maternal hypertension or placental abruption are associated with further changes in the hemostatic profile of these patients.

METHODS

A cross-sectional study included the following: (1) determination of changes in markers of coagulation and platelet activation in patients with a normal pregnancy (n = 71) and patients with fetal demise (FD) without disseminated intravascular coagulation (n = 65); (2) determination of the amniotic fluid (AF)-tissue factor concentration and activity, as well as the concentrations of thrombin-antithrombin III (TAT) complexes in patients with a normal pregnancy (n = 25) and those with a FD (n = 36) who underwent amniocentesis. Plasma and AF concentrations of TAT complexes and TF (an index of thrombin generation), as well as maternal plasma concentrations of sCD40L (a marker of platelet activation), tissue factor pathway inhibitor (TFPI) and prothrombin fragments (PF) 1 + 2 (also an indicator of in vivo thrombin generation) were measured by ELISA. TF and TFPI activity were measured using chromogenic assays.

RESULTS

(1) patients with FD without hypertension had a higher median maternal plasma sCD40L concentration than normal pregnant women (P < 0.001); (2) patients with FD had a higher median maternal plasma TAT III complexes than women with a normal pregnancy (P < 0.001); (3) the median AF-TF concentration and activity were higher in the FD group than in the normal pregnancy group (P < 0.001 for both); (4) patients with preeclampsia and FD had a higher median maternal plasma immunoreactive TF concentration than both normotensive patients with FD and women with normal pregnancies (P < 0.001 and P = 0.001, respectively); (5) the median plasma TF activity was higher in patients with preeclampsia and FD than that of women with normal pregnancies (P = 0.003); (6) among patients with a FD, those with placental abruption had a higher median AF-TAT complexes concentration than those without abruption (P = 0.0004).

CONCLUSIONS

Our findings indicate that: (1) mothers with a FD have evidence of increased in vivo thrombin generation and platelet activation than women with normal pregnancies; (2) patients with a FD and hypertension had a higher degree of TF activation than those with fetal death but without hypertension; (3) the AF of women with a FD had a higher median TF concentration and activity than that of normal pregnant women. AF can be a potential source for tissue factor and it participates in the development of fetal death syndrome in patients with a retained dead fetus.

Changes in amniotic fluid concentration of thrombin-antithrombin III complexes in patients with preterm labor: evidence of an increased thrombin generation

OBJECTIVE

Preterm labor is associated with excessive maternal thrombin generation, as evidenced by increased circulating thrombin-antithrombin (TAT) III complexes concentration. In addition to its hemostatic functions, thrombin has uterotonic properties that may participate in the mechanism leading to preterm birth in cases of intrauterine bleeding. Thrombin also has a proinflammatory role, and inflammation is associated with increased thrombin generation. The aim of this study was to determine whether intra-amniotic infection/inflammation (IAI) is associated with increased amniotic fluid (AF) thrombin generation in women with preterm and term deliveries.

STUDY DESIGN

This cross-sectional study included the following groups: (1) mid-trimester (n = 74); (2) term not in labor (n = 39); (3) term in labor (n = 25); (4) term in labor with IAI (n = 22); (5) spontaneous preterm labor (PTL) who delivered at term (n = 62); (6) PTL without IAI who delivered preterm (n = 59); (7) PTL with IAI (n = 71). The AF TAT III complexes concentration was measured by enzyme linked immunosorbent assay (ELISA). Non-parametric statistics were used for analysis.

RESULTS

(1) TAT III complexes were identified in all AF samples; (2) patients with PTL who delivered preterm, with and without IAI, had a higher median AF TAT III complexes concentration than those with an episode of PTL who delivered at term (p < 0.001, p = 0.03, respectively); (3) among patients with PTL without IAI, elevated AF TAT III complexes concentration were independently associated with a shorter amniocentesis-to-delivery interval (hazard ratio, 1.5; 95% CI, 1.07-2.1); (4) among patients at term, those with IAI had a higher median AF TAT III complexes concentration than those without IAI, whether in labor or not in labor (p = 0.02); (5) there was no significant difference between the median AF TAT III complexes concentration of patients at term with and without labor; (6) patients who had a mid-trimester amniocentesis had a lower median AF TAT III complexes concentration than that of patients at term not in labor (p < 0.001).

CONCLUSIONS

We present herein a distinct difference in the pattern of intra-amniotic thrombin generation between term and preterm parturition. PTL leading to preterm delivery is associated with an increased intra-amniotic thrombin generation regardless of the presence of IAI. In contrast, term delivery is associated with an increased intra-amniotic thrombin generation only in patients with IAI.

Over-expression of the thrombin receptor (PAR-1) in the placenta in preeclampsia: a mechanism for the intersection of coagulation and inflammation

OBJECTIVE

Preeclampsia (PE) is characterized by excessive thrombin generation, which has been implicated in the multiple organ damage associated with the disease. The biological effects of thrombin on coagulation and inflammation are mediated by protease-activated receptor-1 (PAR-1), a G protein-coupled receptor. The aim of this study was to determine whether preterm PE is associated with changes in placental expression of PAR-1.

STUDY DESIGN

This cross-sectional study included two groups matched for gestational age at delivery: (1) patients with preterm PE (<37 weeks of gestation; n = 26) and (2) a control group of patients with preterm labor without intra-amniotic infection (n = 26). Placental tissue microarrays were immunostained for PAR-1. Immunoreactivity of PAR-1 in the villous trophoblasts was graded as negative, weak-positive, or strong-positive.

RESULTS

(1) The proportion of cases with strong PAR-1 immunoreactivity was significantly higher in placentas of patients with PE than in placentas from the control group (37.5% (9/24) vs. 8.7% (2/23); p = 0.036, respectively). (2) PAR-1 immunoreactivity was found in the cellular compartments of the placental villous tree, mainly in villous trophoblasts and stromal endothelial cells. (3) PAR-1 was detected in 92.3% (24/26) of the placentas of women with PE and in 88.5% (23/26) of the placentas from the control group.

CONCLUSION

Placentas from pregnancies complicated by preterm PE had a significantly higher frequency of strong PAR-1 expression than placentas from women with spontaneous preterm labor. This observation is consistent with a role for PAR-1 as a mediator of the effect of thrombin on coagulation and inflammation in PE. We propose that the effects of thrombin in PE are due to increased thrombin generation and higher expression of PAR-1, the major receptor for this enzyme.

Candidate-gene association study of mothers with pre-eclampsia, and their infants, analyzing 775 SNPs in 190 genes

Pre-eclampsia (PE) affects 5-7% of pregnancies in the US, and is a leading cause of maternal death and perinatal morbidity and mortality worldwide. To identify genes with a role in PE, we conducted a large-scale association study evaluating 775 SNPs in 190 candidate genes selected for a potential role in obstetrical complications. SNP discovery was performed by DNA sequencing, and genotyping was carried out in a high-throughput facility using the MassARRAY(TM) System. Women with PE (n = 394) and their offspring (n = 324) were compared with control women (n = 602) and their offspring (n = 631) from the same hospital-based population. Haplotypes were estimated for each gene using the EM algorithm, and empirical p values were obtained for a logistic regression-based score test, adjusted for significant covariates. An interaction model between maternal and offspring genotypes was also evaluated. The most significant findings for association with PE were COL1A1 (p = 0.0011) and IL1A (p = 0.0014) for the maternal genotype, and PLAUR (p = 0.0008) for the offspring genotype. Common candidate genes for PE, including MTHFR and NOS3, were not significantly associated with PE. For the interaction model, SNPs within IGF1 (p = 0.0035) and IL4R (p = 0.0036) gave the most significant results. This study is one of the most comprehensive genetic association studies of PE to date, including an evaluation of offspring genotypes that have rarely been considered in previous studies. Although we did not identify statistically significant evidence of association for any of the candidate loci evaluated here after adjusting for multiple testing using the false discovery rate, additional compelling evidence exists, including multiple SNPs with nominally significant p values in COL1A1 and the IL1A region, and previous reports of association for IL1A, to support continued interest in these genes as candidates for PE. Identification of the genetic regulators of PE may have broader implications, since women with PE are at increased risk of death from cardiovascular diseases later in life.

Thrombin-antithrombin complex and alpha-plasmin inhibitor-plasmin complex levels in singleton and twin pregnancies

Thrombin-antithrombin complex (TAT) is a sensitive marker for thrombin formation, and alpha2-plasmin inhibitor-plasmin complex (PIC) is a marker for fibrinolysis. Previous studies have shown that blood coagulation and fibrinolysis are activated in normal pregnancies. Thus, the present study examined changes in TAT and PIC levels during the course of singleton and twin pregnancies and compared these markers between the two pregnant groups. The subjects were 148 pregnant women, of whom 84 were women carrying single fetuses and 64 were women with twin fetuses. Their average gestational age at entry was 10, 20, 30 and 38 weeks of gestation in singleton pregnancies and 10, 20, 30 and 35 weeks in twin pregnancies. Peripheral blood was collected, and plasma was separated after centrifugation and then stored at -20 degrees C. The TAT levels increased significantly with the progression of pregnancy in both pregnant groups, whereas the PIC levels increased significantly only in singleton pregnancies between 30 and 38 weeks of gestation. The TAT levels were significantly higher in twin pregnancies than in singleton pregnancies. The PIC levels were significantly lower in twin pregnancies than in singleton pregnancies at 35-38 weeks. Thrombin formation might be enhanced with the progression of pregnancy in both pregnant groups. This enhancement might be more intensified in twin pregnancies. Fibrinolysis might increase only in singleton pregnancies from 30 to 38 weeks of gestation. Fibrinolysis might be less intensified in twin pregnancies than in singleton pregnancies only at 35-38 weeks.

Haemostasis in normal and abnormal pregnancy

Haemostasis is a complex and dynamic equilibrium involving pro-coagulants, the natural anticoagulation system and fibrinolysis. Normal human pregnancy is associated with profound alterations to the process of haemostasis such that the pro-coagulant effect becomes dominant. There are very few studies which have attempted to elucidate the adaptations that take place in the uteroplacental circulation where the haemostatic system faces the conflicting tasks of maintaining blood fluidity during pregnancy while preparing for the haemostatic challenge of delivery. It is hypothesised that excessive thrombosis within the uteroplacental circulation provides the mechanistic basis for the reported associations between the inherited thrombophilias and major pregnancy complications. The evidence underpinning this widely quoted hypothesis is weak.

Maternal diabetes mellitus is associated with altered deposition of fibrin-type fibrinoid at the villous surface in term placentae

Placentae from control and diabetic patients were used to test three null hypothesis: (1) there are no significant group differences in the volumes of villous syncytiotrophoblast compartments or intervillous fibrin-type fibrinoid, (2) perivillous fibrin-type fibrinoid is deposited randomly at the surface of trophoblast, and (3) amounts and deposition patterns of perivillous fibrin-type fibrinoid do not vary between groups. Term placentae were collected from non-diabetic subjects and five groups of diabetic women classified according to duration, severity and insulin dependence. Tissue specimens and sections were obtained by uniform random sampling. Volumes and surface areas of fibrin-type fibrinoid and trophoblast compartments (thin, syncytial knot, syncytial bridge and denuded regions) were estimated stereologically and compared using variance, chi-squared and contingency table analyses. As to null hypothesis (1), no group differences in volumes of trophoblast compartments were found but volumes of intervillous fibrin-type fibrinoid were greater in the non-insulin-dependent diabetic group. As to null hypothesis (2), regardless of group, fibrin-type fibrinoid was deposited preferentially at sites of denudation in every placenta examined. As to null hypothesis (3), villous surface areas occupied by perivillous fibrin-type fibrinoid were greater in type 1 (insulin-dependent) diabetics with complications (diabetic nephropathy or retinopathy). The surfaces of trophoblast occupied by fibrin-type fibrinoid were also notably larger in non-insulin-dependent diabetics and type 1 diabetics with complications. Except for the surface of denudation sites (which also increased in diabetes), there were no differences in the surfaces of trophoblast regions. These results confirm that the haemostatic steady state is perturbed in the diabetic placenta, that perivillous fibrin-type fibrinoid is deposited preferentially at sites of epithelial loss/damage, and that some diabetic groups are affected differentially.

Fibrin-type fibrinoid in placentae from pregnancies associated with maternal smoking: association with villous trophoblast and impact on intervillous porosity

Smoking during pregnancy perturbs maternal haemostasis via activated coagulation which could include greater coagulation (fibrin-type fibrinoid deposition) in the placental intervillous space. This might affect intervillous haemodynamics and transport of oxygen and nutrients to the fetus. Fibrin deposits could influence the sizes and numbers of intervillous spaces ('pores') and perivillous fibrin could reflect changes in the nature or activity of trophoblast. Here, we test whether or not smoking is associated with differences in the composition of villous trophoblast, the amounts and patterns of fibrin and, hence, the dimensions and numbers of intervillous pores. Random samples of placentae were taken from pregnancies classified according to smoking status (non-smokers, light smokers, heavy smokers). Stereology was used to estimate volumes of intervillous space and fibrin, test for differences in trophoblast composition and patterns of fibrin deposition at the villous surface, and determine the impact of deposits on the mean volumes and theoretical numbers of intervillous pores. No group differences were found in total volumes or surfaces of trophoblast or total volume of intervillous fibrin. However, the total surfaces of syncytial knots declined in smokers and the surfaces of syncytial bridges increased. Particularly in heavy smokers, this was associated with reduced deposits of perivillous fibrin at syncytial knots. In all placentae, the greatest deposits occurred where there was trophoblast denudation. Little fibrin was seen on thin regions of syncytium. Regardless of smoking status, intervillous fibrin reduced intervillous pore size and increased pore number. However, heavy smokers had larger pores. Reductions in syncytial knots are consistent with reports that smoking reduces the incidence of trophoblast apoptosis whilst increases in syncytial bridges are consistent with enhanced branching angiogenesis. Results confirm that perivillous fibrin accumulates preferentially at denudation sites. They also suggest that smoking perturbs the normal pattern of fibrin deposition, that the impact is greater in heavy smokers and that the placental site is privileged or active in terms of fibrinolytic or anti-coagulatory activity. This activity seems to reside in thin regions of syncytium.

Characterization of five marker levels of the hemostatic system and endothelial status in normotensive pregnancy and pre-eclampsia

OBJECTIVES

Pre-eclampsia is associated with changes in the hemostatic system and endothelial status. Urinary 11-dehydrothromboxane B2/creatinine (11-DTXB2/Cr) is a marker for platelet activation and vascular constriction, thrombin-antithrombin complex (TAT) for thrombin formation, serum thrombomodulin (TM) for endothelial damage, and beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) for platelet activation and releasing reaction. The present study attempted to evaluate these five markers in normotensive pregnancy and pre-eclampsia.

METHODS

These five markers were simultaneously measured in urine and blood samples from 25 women who were not pregnant (group 1, controls), 31 women with normotensive pregnancy (group 2, second controls), 22 women with mild pre-eclampsia (group 3), and 21 women with severe pre-eclampsia (group 4). The average gestational age was 36 wk.

RESULTS

The 11-DTXB2/Cr, TAT, and beta-TG levels were significantly higher (P < 0.01) in groups 2, 3, and 4 than in group 1. The TM and beta-TG levels were significantly higher (P < 0.05) in group 3 than in group 2. The TM, beta-TG, and PF-4 levels were increased significantly (P < 0.05-0.01) in group 4 compared to those in groups 1, 2, and 3.

CONCLUSION

Platelet aggregation, vascular constriction, and thrombin formation (detected by 11-DTXB2/Cr and TAT) may be markedly enhanced even in group 2, but further enhancement may be relatively slight in groups 3 and 4. In contrast, endothelial damage (determined by TM) and platelet release of PF-4 may not increase significantly in group 2, but they may increase in group 4. Platelet-release of beta-TG may be enhanced in groups 2, 3, and 4. Endothelial damage and platelet-releasing reaction (detected by PF-4 and beta-TG) may be significantly more enhanced in group 4 than in group 3.

Evidence of in vivo generation of thrombin in patients with small-for-gestational-age fetuses and pre-eclampsia

OBJECTIVE

Thrombotic lesions in the maternal or fetal compartments are frequently observed in the placentas of patients with small-for-gestational-age (SGA) fetuses and in pre-eclampsia. The objective of this study was to determine whether there was evidence of in vivo generation of thrombin, the rate-limiting enzyme responsible for the formation of fibrin. The plasma concentrations of thrombin-antithrombin (TAT) complexes were used as an index of thrombin generation.

METHODS

TAT complexes were measured in the plasma from 68 women from the following groups: normal pregnancy (n = 29); pre-eclampsia (n = 26); and SGA (defined as estimated fetal weight below the 10th centile for gestational age, which was confirmed by neonatal birth weight) (n = 13). TAT complex plasma concentrations were determined with a specific and sensitive immunoassay. Statistical analysis was performed with non-parametric statistics.

RESULTS

The median plasma TAT complex concentrations were significantly higher in patients who delivered SGA neonates than in normal pregnant women (SGA, median 24.2 microg/l; range 11.9-788.7 vs. normal pregnancy, median: 14.4 microg/l; range 6.8-26.9; p = 0.001). Patients with pre-eclampsia had a higher median plasma TAT complex concentration than normal pregnant women (pre-eclampsia, median 18.1 microg/l; range 10.0-75.2 vs. normal pregnancy, median 14.4 microg/l; range 6.8-26.9; p = 0.02).

CONCLUSION

In vivo generation of thrombin, determined by the plasma concentrations of TAT complexes, is higher in patients with SGA fetuses and patients with pre-eclampsia than in normal pregnancy.

The levels of five markers of hemostasis and endothelial status at different stages of normotensive pregnancy

BACKGROUND

Urinary 11-dehydrothromboxane B(2)/creatinine (11-DTXB(2)/Cr) is a marker for in vivo platelet activation and vascular constriction, blood thrombomodulin (TM) for endothelial damage and associated thrombosis, thrombin-antithrombin complex (TAT) for thrombin formation, and beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) for in vivo platelet activation and releasing reaction. Little is known about the quantitative relationship among them during pregnancy. The present study investigated levels of five markers at different stages of normotensive pregnancy.

METHODS

Subjects were 17 healthy non-pregnant women (Group 1, control) and 67 women carrying single fetuses in normotensive pregnancy. Of the pregnant women, 17 were in the 20th week of gestation (Group 2), 20 were in their 30th week (Group 3), and 30 were in their 36th week (Group 4). Urinary and circulating blood levels of 11-DTXB(2)/Cr, TM, TAT, beta-TG, and PF-4 were measured simultaneously.

RESULTS

The 11-DTXB(2)/Cr and TAT levels showed elevated values at the 20th and 30th weeks of gestation, and markedly elevated values at the 36th week, whereas the TM level remained constant throughout pregnancy. The beta-TG and PF-4 levels maintained stable values at the 20th week, but showed elevated values at the 30th and 36th weeks.

CONCLUSIONS

Platelet aggregation, vascular constriction, and thrombin formation (detected by 11-DTXB(2)/Cr and TAT) appear to be enhanced as early as the 20th week of gestation, continuously enhanced by the 30th week, and markedly enhanced by the 36th week. Platelet activation and releasing reaction (determined by beta-TG and PF-4) gradually enhanced from the 30th to 36th weeks. In contrast, endothelial damage and associated thrombosis (detected by TM) were minimal throughout pregnancy. Investigating these markers of hemostasis and endothelial function in normotensive pregnancy may provide insights into related disease states.

Increased levels of macrophage colony-stimulating factor in the placenta and blood in preeclampsia

PROBLEM

Macrophage colony-stimulating factor (M-CSF) is considered an essential cytokine for placental growth and maintenance. We evaluated whether M-CSF levels in the placenta and blood in preeclampsia differed from those in normal pregnancies.

METHOD OF STUDY

The subjects were 37 pregnant women carrying single fetuses, of whom 19 were women with normal pregnancies and 18 were women with preeclampsia. Their average gestational age at entry was 38 weeks of gestation. Blood was collected before the onset of labor, and separated serum was obtained after centrifugation. A tissue segment of the placenta was cut immediately after delivery. The frozen placental tissue was placed in a plastic tube containing phosphate-buffered saline. The tissue was fully homogenized and then centrifuged. Separated supernatant was used for subsequent determination. M-CSF levels in separated serum were measured, and M-CSF and total protein (TP) levels in separated supernatant were also measured.

RESULTS

Both M-CSF/TP levels in the placenta and M-CSF levels in blood were significantly higher (P < 0.05-0.01) in preeclampsia than in normal pregnancies.

CONCLUSIONS

This is the first report concerning high placenta levels of M-CSF/ TP in preeclampsia. Increased M-CSF in the placenta supports the hypothesis that immunological abnormalities contribute to the etiology of preeclampsia.

Interaction of the protein C/protein S anticoagulant system, the endothelium and pregnancy

Normal pregnancy is associated with significant changes in haemostasis, lipid metabolism and endothelial function. This suggests that maternal adaptation in these systems is required for successful pregnancy outcome. A number of acquired and heritable prothrombotic abnormalities are associated with complications in pregnancy. A common feature of these abnormalities is their ability to alter endothelial function or the protein C/protein S system and increase thrombin generation. In this review the normal function of the endothelium and the protein C/protein S system is detailed. The changes which characterize normal and complicated pregnancies are outlined and the evidence for the impact of heritable and acquired disorders of the protein C/protein S system on pre-eclampsia and fetal loss are discussed.

Measurement of prethrombotic markers in the assessment of acquired hypercoagulable states

Hypercoagulable states can be detected by measuring activation peptides, enzyme-inhibitor complexes, and fibrin/fibrinogen degradation products, which are markers of hemostatic activation. A series of these prethrombotic markers has been evaluated in the elderly, pregnancy, diabetes and acute myocardial infarction patients (n=30 in each group) as well as in hematologic malignancies (n=42). The parameters assayed were: prothrombin fragment 1+2 (F1+2), thrombin-antithrombin III complexes (TAT), fibrinopeptide A (FPA), plasmin-alpha2 antiplasmin complexes (PAP) and D-Dimer. Results were compared with those obtained in a group of 30 healthy subjects. We found a significant increase of F1+2, TAT and FPA in elderly (p<0.05), acute myocardial infarction (AMI) (p<0.01), hematologic malignancies (p<0.01), and pregnancy (p<0.0001), indicating a marked clotting activation. Diabetic patients under strict metabolic control only presented a moderate increase of TAT (p<0.05), suggesting a slight activation. We also observed a highly significant elevation of PAP and D-Dimer in elderly (p<0.001), AMI (p<0.0001), and malignancy (p<0.0001), indicating an activation of the fibrinolytic system. The combination of selected fibrinolytic and coagulation measurements is useful for the detection of a hypercoagulable state in conditions characterized by a risk of thrombosis.

Hemostasis in the uteroplacental and peripheral circulations in normotensive and pre-eclamptic pregnancies

OBJECTIVE

Our purpose was to determine the hemostatic changes in the uteroplacental and peripheral circulations in normotensive and pre-eclamptic pregnancies.

STUDY DESIGN

This prospective, observational study involved 2 patient groups. Group 1 consisted of 30 normotensive women and 22 women with pre-eclampsia who were followed up longitudinally through pregnancy and post partum. Group 2 consisted of 20 women with established pre-eclampsia and 19 normotensive control subjects, all undergoing cesarean section. Plasma levels of thrombin-antithrombin III complex, soluble fibrin, plasmin-alpha2-antiplasmin complex, and fibrin-degradation product (D-dimer) were measured in blood drawn from the antecubital vein (group 1) and from both the antecubital and uterine veins (group 2). Data were analyzed by analysis of variance.

RESULTS

In group 1 levels of thrombin-antithrombin III complex, soluble fibrin, and fibrin-degradation product were significantly higher during normal pregnancy than at 6 weeks post partum. Plasmin-alpha2-antiplasmin complex levels did not change. No differences between the pre-eclamptic and normotensive pregnancy groups were found for any of the hemostatic markers. In group 2 normotensive women undergoing cesarean section, thrombin-antithrombin III complex and soluble fibrin levels were significantly higher in the uterine vein than in the antecubital vein. In group 2 women with pre-eclampsia, thrombin-antithrombin III complex and fibrin-degradation product levels were significantly higher in the uterine vein than in the antecubital vein. In addition, plasmin-alpha2-antiplasmin complex and fibrin-degradation product levels were higher and soluble fibrin levels were lower in the uterine vein in the pre-eclamptic group than in the normotensive group.

CONCLUSION

Both the coagulation and fibrinolytic systems are activated during normal pregnancy. Activation of these systems is more marked in the uteroplacental circulation than in the systemic circulation in both normotensive and pre-eclamptic pregnancies. An abnormal pattern of hemostasis occurs in the uteroplacental circulation in pre-eclampsia.

Anticoagulant dermatan sulfate proteoglycan (decorin) in the term human placenta

Normal pregnancy is characterized by increased in vivo thrombin generation. A greater proportion of endogenously generated thrombin is complexed to heparin cofactor II in plasma from pregnant women compared to plasma from nonpregnant ones. The increase in thrombin-heparin cofactor II complexes suggests that the site of the additional thrombin generation is relatively rich in dermatan sulfate. We postulated that the site of thrombin generation may be the placenta since endogenous thrombin generation returns rapidly to normal after delivery. This report describes the isolation and characterization of placental dermatan sulfate proteoglycan from villous tissue of the term human placenta. Placental dermatan sulfate was isolated by guanidine HCI extraction and anion exchange chromatography. The isolated material was found to have anticoagulant activity with a relative activity of approximately 40% of that of a porcine mucosal dermatan sulfate which is undergoing clinical trial as an antithrombotic agent. The dermatan sulfate was present as a proteoglycan with a molecular mass of 90-150 kD. Upon degradation with chondroitin ABC lyase, the core protein was demonstrated to be a doublet with molecular masses of 42 and 44 kD. This core protein reacted with antiserum against the core protein of decorin on Western analysis. The role of this placental dermatan sulfate in local regulation of thrombin in the placenta warrants further study.

Blood macrophage colony-stimulating factor and thrombin-antithrombin III complex concentrations in pregnancy and preeclampsia

Macrophage colony-stimulating factor (M-CSF) is a characteristic cytokine that plays an essential role in placenta maintenance, and thrombin-antithrombin III complex (TAT) is a hemostatic marker that is remarkably altered both in normal pregnancy and in preeclampsia. The present study was designed in order to show various levels of M-CSF and TAT in pregnancies. Peripheral blood was collected from 49 subjects, of whom 31 were normal pregnant women consisting of the four groups (namely 10th, 20th, 30th, and 38th weeks of gestation), 13 were preeclamptic pregnant women (37th week of gestation; mean blood pressure, 158/99 mm Hg), and 5 were nonpregnant controls. We compared blood M-CSF and TAT levels among them. Results showed that blood M-CSF and TAT levels increased significantly with gestational age. Furthermore, the ratio of increase in M-CSF was significantly lower than that in TAT in normal pregnant women compared with controls. In contrast, the ratio of increase in M-CSF was significantly higher than that in TAT in preeclamptic women compared with normal pregnant women. These results concerning the ratio of increase in M-CSF and TAT have not been reported. These findings show that M-CSF level increases significantly in preeclampsia even in its earlier stage, exhibiting a systolic blood pressure of less than 160 mm Hg.

Generation of thrombin in blood plasma of non-pregnant and pregnant women studied through concentration of thrombin-antithrombin III complexes

OBJECTIVE

The main question in this study is how much more thrombin is generated in blood plasma of pregnant women than in non-pregnant women.

STUDY DESIGN

Thrombin-antithrombin III complexes (TAT) were used as markers of thrombin generation in vivo. They were measured by the ELISA method in blood plasma of 15 non-pregnant and 43 pregnant, as well as 30 parturient women and 10 women after delivery.

RESULTS

With normal menstrual cycles, TAT levels did not change significantly throughout the cyclic phases, and the mean +/- S.D. calculated for all cyclic phases was 1.9 +/- 0.3 micrograms/l. In the 2nd trimester the level of TAT was 16.0 +/- 2.8 micrograms/l and at term 21.5 +/- 11.9 micrograms/l. Throughout the 1st and 2nd stage of labour the level of TAT increased insignificantly, but after placenta separation it was significantly higher than before labour (30.8 +/- 20.4 micrograms/l). In the 3rd and 7th days after delivery the level of TAT was still higher than in non-pregnant women.

CONCLUSION

It was found that the level of TAT in normal menstrual cycles is stable, whereas it increases in pregnancy. Relating the values of the cycle to those of pregnancy it was calculated, that at the end of pregnancy there is a ten-fold increase of TAT level and after placenta separation and expulsion--temporarily even fifteen-fold--increase. In the 3rd to 7th day after delivery, the TAT level was still higher than in non-pregnant women.

Coagulation and fibrinolysis in smoking and nonsmoking pregnant women

OBJECTIVES

To assess the effects of smoking during pregnancy on coagulation and fibrinolysis.

DESIGN

A cross-sectional study.

SETTING

A teaching hospital in Heerlen, The Netherlands.

RESULTS

Parameters of coagulation activation increased significantly with gestational age. The values presented are median values. Prothrombin fragment 1 + 2 increased from 0.8 to 2.5 nmol/l in the nonsmoking group of pregnant women and from 1.0 to 1.8 nmol/l in the smoking group. Thrombin-antithrombin III (TAT) levels increased from 2.2 to 9.9 micrograms/l in the nonsmoking group and from 3.1 to 8.5 micrograms/l in the smoking group. Parameters of fibrinolysis showed a different picture. Plasminogen levels in both groups rose significantly in the first half of gestation reaching a plateau in the second half. The alpha 2-antiplasmin levels remained constant in both groups, although the smokers started with significantly higher levels: 119 versus 105% in the nonsmokers. The D-dimer levels rose significantly in both groups: from 278 to 847 micrograms/ml in the nonsmokers and from 215 to 520 micrograms/ml in the smokers. They were significantly lower in the smoking group from the 11th up to the 40th weeks. The D-dimer/TAT ratio was significantly higher in the nonsmokers.

CONCLUSIONS

In smoking pregnant women the activated coagulation process was not counter balanced by an adequate increase of fibrinolysis which was the case in the nonsmokers.

Thrombin-inhibitor complexes in the blood during and after delivery

Activation of coagulation leads to generation of thrombin which in turn is inactivated by the formation of thrombin-antithrombin (TAT) complexes, and thrombin-heparin cofactor complexes (T-HCII). These complexes were measured in plasma by ELISA methods. During normal delivery, the median TAT level in ten women increased from 4.1 to 7.8 times the median normal reference level. There was great individual variation, and levels 42 and 56 times normal median were found in two women shortly after normal delivery. The median T-HCII levels increased only moderately from 2.3 to 3.1 times median normal reference. D-dimer values were elevated in 28 out of the 30 samples. In blood sampled 1-2 days after delivery, the median TAT level was 2.5 times the median normal reference. The median T-HCII level was now 5.6 times the median normal reference value. The values were stable during the first 4 days post partum, and there was little difference between those delivered vaginally or by Caesarean section (C-section). D-dimer values were above normal reference in all women, and higher in women delivered by C-section. In conclusion, increasing TAT levels during labour and delivery indicated generation of thrombin which was mainly inactivated by antithrombin. The T-HCII levels increased less during delivery. In the early post partum period, the T-HCII levels were relatively more increased than the TAT levels. These results suggest that intravascularly generated thrombin is preferably inactivated by antithrombin, even in parturient women. In the post partum period, formation of T-HCII complexes was more evident, possibly reflecting extravascular inactivation of thrombin.

The laboratory evaluation of hypertensive gravidas

A number of laboratory tests are available for the evaluation of the hypertensive gravida. These tests can be used to either predict and/or prognosticate between preeclampsia and other hypertensive disorders of pregnancy. These laboratory tests were evaluated based on published experience with special attention to its ability to facilitate identification of the patient with preeclampsia apart from other hypertensive disorders that co-exist with and occur as a complication of pregnancy. Hypocalciuria and increased cellular plasma fibronectin seem to be good tests to differentiate preeclampsia from chronic hypertension. The management of preeclampsia with its increased risk of perinatal morbidity and mortality renders this differentiation clinically very important. Hyperuricemia, proteinuria, increased serum beta-thromboglobulin concentration, abnormal red blood cell morphology with increased hemoglobin/hematocrit, and increased serum iron individually and collectively reflect the severity of preeclampsia. Platelets and total serum lactate dehydrogenase are the best tests to reflect the severity of HELLP syndrome. Circulating hCG and serum thromboglobulin seem to be the most promising future predictors for preeclampsia.

Haemostatic, fibrinolytic and endothelial variables in normal pregnancies and pre-eclampsia

OBJECTIVE

To determine the behaviour of the coagulation variables antithrombin III (ATIII), protein C, thrombin/antithrombin III (TATIII); fibrinolytic activity, tissue plasminogen activator antigen (t-PA), plasminogen activator inhibitors (PAI) 1 and 2, and endothelial involvement by fibronectin assay in normal and pre-eclamptic pregnancies.

DESIGN

Longitudinal and cross-sectional observational study.

SETTING

Antenatal clinic and maternity hospital.

SUBJECTS

Thirty-six primigravid normotensive caucasian patients, four of whom subsequently developed pre-eclampsia, and 12 patients with established pre-eclampsia.

MAIN OUTCOME MEASURES

Plasma levels of PAI-1, PAI-2 and t-PA antigen were determined using an ELISA technique as were TATIII complex levels of fibronectin. ATIII and protein C plasma levels were assayed using chromogenic substrate techniques.

RESULTS

PAI-1 and PAI-2 antigen levels rose progressively throughout normal pregnancy. Among the established pre-eclamptic group compared with matched normal pregnancies, the PAI-2 antigen level was significantly lower (48.5 +/- 22.8 versus 183.5 +/- 37.4; P < 0.001), the PAI-1 antigen level was significantly higher (122 +/- 34.4 versus 79.2 +/- 19.7; P < 0.001), ATIII activity was significantly lower (87.8 +/- 27.1 versus 110.9 +/- 19.3; P < 0.001) and TATIII complex levels were significantly higher (16.9 +/- 6.4 versus 10.2 +/- 5.9; P < 0.001). Among the four initially normotensive patients who subsequently developed pre-eclampsia, fibronectin levels were significantly elevated from as early as nine weeks of gestation.

CONCLUSION

Significantly elevated levels of PAI-1 and fibronectin occurring early in pregnancies that subsequently develop pre-eclampsia suggest that these variables may have predictive values. PAI-2 would seem to be a marker of placental function in pre-eclampsia while increased t-PA and TATIII complex levels reflect the severity of the condition.

The value of antithrombin-III and fibronectin in hypertensive disorders of pregnancy

In this study we evaluated fibronectin as a marker of endothelial cell injury and antithrombin III as a marker of chronic activation of intravascular coagulation. The aim of the study was to establish to normal trends of plasma antithrombin III and fibronectin in general obstetric population and to determine the value of both in predicting, distinguishing and understanding the pathophysiology of pregnancy induced hypertension. The all cases consisted of 173 pregnant, 19 of them were chronic hypertensive, 45 were pregnancy induced hypertensive and 119 were normotensive at blood sampling. Out of 119 normotensive cases, 109 cases had no adverse outcome during their pregnancy. These cases were used as a control group and for the normal trends of antithrombin III and fibronectin in general obstetric population. Ten out of 119 cases who developed preeclampsia during follow up, 19 cases with chronic hypertension and 45 cases with pregnancy induced hypertension consisted of the study group. In the cases who developed preeclampsia during follow up, the value of plasma fibronectin level (above 95% confidence limit for that gestational week) to predict preeclampsia had 90% sensitivity and 94.4% specificity. In distinguishing hypertensive disorders of pregnancy (chronic hypertension or pregnancy induced hypertension) fibronectin had 71.1% sensitivity and 100% specificity. Plasma antithrombin III level (of antigenicity) measured by immunodiffusion method had no value in predicting and distinguishing pregnancy induced hypertension.

Evaluation of six markers of haemostatic system in normal pregnancy and pregnancy complicated by hypertension or pre-eclampsia

OBJECTIVE

To establish the plasma evolution of prothrombin fragments 1+2 (F 1+2), thrombin-antithrombin III complexes (TAT), fibrin fragment D-Dimers (DD), von Willebrand factor antigen (vWf), Type 1 plasminogen activator inhibitor antigen (PAI) and blood platelet count during normal pregnancy and to compare these values with those obtained in hypertensive or pre-eclamptic pregnancies.

DESIGN

Cross-sectional study.

SUBJECTS

Forty-seven healthy pregnant women with gestational age ranging between 5 and 40 weeks, and fourteen women with gestational age ranging between 25 and 38 weeks presenting with either gestational hypertension (n = 4) or pre-eclampsia (n = 10). Numbers of nulliparous women in the control, hypertension and pre-eclampsia groups were 13/47 (28%), 1/4 (25%) and 9/10 (90%), respectively.

RESULTS

All six markers increased with gestational age in normal pregnant women (P < 0.01). Using the upper limit of 95% prediction interval obtained from regression curves as normality threshold, TAT showed the best sensitivity (71% vs < 30% for F1+2, DD, vWf, PAI and platelet count).

CONCLUSION

TAT appears to be an interesting marker for detecting haemostatic system alterations in pregnancies complicated by hypertension or pre-eclampsia. A large prospective study to determine its clinical usefulness for such complicated pregnancies is currently in progress.

Prophylactic antithrombin III administration during pregnancy immediately reduces the thrombin hyperactivity of congenital antithrombin III deficiency by forming thrombin-antithrombin III complexes

We examined the changes of haemostatic molecular markers after antithrombin III (AT III) administration in a 22-year-old woman with congenital AT III deficiency in the third trimester of pregnancy who did not have thrombosis. Various markers including fibrinopeptide A (FPA), thrombin-antithrombin III complex (TAT), prothrombin fragment F1 + 2 (F1 + 2), plasmin-alpha 2antiplasmin, D-dimer, beta-thromboglobulin, and platelet factor 4 were measured before and just after 3,000 U of AT III concentrate, which was given three times per week from the 34 week of pregnancy until delivery. Just after AT III administration, F1 + 2 and FPA levels decreased on most occasions, while TAT sometimes increased. Plasma FPA levels were markedly decreased on all 8 occasions when the plasma FPA levels was above 2.0 ng/ml before AT III administration. Plasma FPA levels were always greater than or equal to 6.4 ng/ml before AT III administration on the 4 occasions when TAT increased to above 115%. The changes of plasma F1 + 2 levels were significantly correlated with the AT III level. These results suggest that prophylactic AT III administration in the third trimester immediately inactivates intravascular thrombin to form TAT and reduce the plasma FPA level. Thus, the transient TAT elevation following AT III administration may not only be due to extraction of thrombin from the fibrin clots of thrombi but also to intravascular thrombin which is not attached to thrombi. FPA is the best molecular marker for thrombin hyperactivity and it should be monitored in AT III-deficient pregnant women in the third trimester.

A locus on the long arm of chromosome 1 as a possible cause of essential hypertension

1. None of the genes responsible for essential hypertension has been identified. Recent work in genetically hypertensive rats has shown linkage of blood pressure with alleles of the renin gene. Since the renin gene is a member of a conserved synteny group that in humans spans chromosome 1q21.3-32.3 and includes the gene for antithrombin III (AT3), we used linkage studies to examine the relationship between alleles of AT3 and hypertension in a family having 10 affected members. 2. From the lod score obtained at a recombination fraction of zero the odds for linkage of AT3 and hypertension in this family were calculated as 6:1 in favour of linkage. This result provides grounds for further examination of the possible role of the 1q23 locus in the aetiology of essential hypertension.