Fibrinolytic enzyme system and pregnancy

Hemostatic Effects of Tranexamic Acid in Cesarean Delivery: An Ancillary Study of the TRAAP2 Study

BACKGROUND

 Fibrinolysis activation during delivery contributes to postpartum hemorrhage (PPH). Clot lysis time studied with the global fibrinolytic capacity device (GFC/LT) is a functional test which rapidly assesses fibrinolytic profile. Tranexamic acid (TXA) is an efficient antifibrinolytic therapy.

METHODS

 We prospectively studied fibrinolysis and coagulation in 33 women included in the TRAAP2 trial, which aimed to assess the impact of TXA in preventing PPH following a cesarean delivery. TXA or placebo was randomly administered after childbirth as part of the TRAAP2 trial's protocol. Fibrinolytic (GFC/LT, plasma concentration of fibrinolysis activators and inhibitors) and hemostatic parameters were assayed at three sample times (TREF [T-reference] after anesthesia, T15 and T120minutes after TXA, or placebo administration).

RESULTS

 All cesarean deliveries were elective. In the placebo group, the clot lysis time assessed with GFC/LT significantly decreased between TREF and T120, indicating an activated fibrinolysis (44 [interquartile range, IQR: 40-48] vs. 34 [IQR: 30-36] minutes, p<0.001). In both TXA and placebo groups, significant fluctuations of the plasmatic concentrations of fibrinolytic mediators were noticed over time, suggesting fibrinolysis activation. Clot lysis time measured by GFC/LT was significantly increased in women of the TXA group as compared with those in the placebo group at T15 (120 [120-120] vs. 36 [34-41] minutes, p<0.001) and T120minutes (113 [99-120] vs. 34 [30-36] minutes, p<0.001) after drug administration, indicating a decreased in fibrinolysis in those women.

CONCLUSIONS

 GFC/LT evidenced fibrinolysis activation during cesarean delivery, linked to a decrease in fibrinolytic inhibitors. GFC/LT revealed a significant antifibrinolytic effect of TXA compared with placebo.

The Influence of Labor and Placental Separation on Hemostasis in Term Pregnancy

We studied the hemostatic effects in 68 term preg nant subjects with normal pregnancy (n = 39), gestational diabetes mellitus (n = 21), pregnancy-induced hypertension (n = 8), during labor, after placental separation, and at 24 hours postpartum. During labor, a hypercoagulable state with en hanced fibrinolysis and platelet activation along with elevated plasminogen activator inhibitor-1 and plasminogen activator inhibitor-2 were seen. In all cases following placental separa tion, enhanced fibrinolysis persisted with further elevated tissue plasminogen activator antigen and D-dimer levels, increased thrombin generation and platelet activation with decreasing plasminogen activator inhibitor-1 levels. By 24 hours postpar tum, thrombin generation (thrombin-antithrombin complex) decreased to a nonpregnant level except for pregnancy induced hypertension, but enhanced prothrombin activation (F1+2) was evident in normal, gestational diabetes mellitus and pregnancy- induced hypertension. Reduced total protein S and antithrom bin III activity with normal protein C and elevated fibrinogen levels seen during labor were not affected by delivery. How ever, although factor VII showed a decreasing trend at 24 hours postpartum it remained elevated above the normal nonpregnant level. At 24 hours postpartum, a hypercoagulable state still persisted in normal, gestational diabetes mellitus and preg nancy-induced hypertension term pregnancy accompanied by enhanced fibrinolysis and elevated plasminogen substrate for fibrinolysis, suggesting a critical dynamic equilibrium between a thrombotic and hemorrhagic state.

Fibrin-based clot formation as an early and rapid biomarker for progression of postpartum hemorrhage: a prospective study

Fibtem is an early and rapidly available biomarker for predicting progression of moderate to severe postpartum hemorrhage. Fibtem was predictive of need for blood transfusion and invasive procedures, bleeds >2500 mL, duration of bleed, and time in high dependency.

Protease concentration in amniotic fluid at term and early childhood respiratory symptoms

OBJECTIVE

Asthma is a common chronic disease associated with altered proteolytic activity. The present study tested the hypothesis that altered protease concentration in amniotic fluid (AF), an index of airway fluid at birth, precedes early cough and wheeze.

METHODS

AF was collected and analysed for the following: matrix metalloproteinases (MMP) -2, -8 and -9, tissue inhibitor of metalloproteinases (TIMP) -1 and 2, plasminogen activator inhibitor (PAI)-1. Infant were followed up at ages 1, 2 and 3 years.

RESULTS

Samples of AF were obtained in 92 infants. There were inconsistent and relatively small differences in some analytes between those individuals with and without symptoms at ages one and two years. PAI-1 concentrations were reduced in association with cough at age 1 year (p = 0.035). Reduced MMP-8:TIMP-2 ratio was associated with wheeze at age 2 years (p = 0.038). There were no associations between AF analytes and symptoms at 3 years of age.

CONCLUSION

There is heterogeneity in concentrations of proteases and their inhibitors in airways at birth but in this exploratory study, there was no consistent evidence that protease concentration at birth was important to later respiratory symptoms.

Coagulation and Fibrinolytic System Protein Profiles in Women with Normal Pregnancies and Pregnancies Complicated by Hypertension

OBJECTIVE: The current study longitudinally evaluated concentrations of fibrinogen (Fib), D-Dimer, plasminogen activator type-1 (PAI-1) and tissue type plasminogen activator (T-Pa) before pregnancy and in the first and third trimesters of pregnancy with a focus on the pregnancy transition. STUDY DESIGN: Twenty healthy, nonsmoking, nulliparous women, aged 29.8 ± 3.0 years, BMI 23.3 ± 3.2 kg/m(2) were studied during menstrual cycle day 8 ± 4 and again in early (11 - 15 wks) and late (31 - 34 wks) pregnancy. Seventeen women had singleton conceptions and delivered at term with uncomplicated pregnancies (CTL) and three women developed complicated hypertension (CH) during pregnancy after the third trimester (late pregnancy) evaluation. Data are means ± SEM, Significance was based on p < 0.05. RESULTS: Fib was the only protein evaluated that increased in early pregnancy relative to the prepregnancy assessment. D-dimer, PAI-1 and T-Pa increased in the third trimester compared with prepregnant and early pregnant values (p < .001). T-PA was significantly higher during late pregnancy in CH subjects compared with CTL (8.1 ± 0.7 ng/ml vs. 5.0 ± 0.2 ng/ml, p = .02). There were no other differences between groups. CONCLUSIONS: Increases in fibrinogen are evident in early pregnancy whereas fibrinolysis, perhaps in response to the procoagulant environment of pregnancy, is increased during late pregnancy. Before development of clinically overt hypertension, T-Pa is increased without concomitant changes in other proteins assessed. This is consistent with altered endothelial function with preeclampsia that may contribute to, or reflect, the vasculopathy accompanying this disorder.

Thrombophilia and pregnancy outcomes

Pregnancy complications are still a challenge for physicians, because knowledge of pathomechanisms and prophylactic measures is still limited. In recent years thrombophilia as a risk factor for pregnancy complications has gained much attention in the scientific community. However, data on this topic in the literature are conflicting. Besides an established association between antiphospholipid antibodies and pregnancy loss, available data suggest additional associations for antithrombin deficiency, hyperhomocysteinemia and also for factor (F)V Leiden, prothrombin G20210A variation, and protein S-deficiency. The contribution of thrombophilia to the risk of pre-eclampsia is less well established and recent studies did not confirm earlier data suggesting an association between thrombophilia and pre-eclampsia. A limited number of prospective studies have failed to reveal an increased risk of pregnancy complications in unselected women with thrombosis risk factors. Low-molecular weight heparin (LMWH) seems to have a positive effect on pregnancy outcome after single or recurrent abortions, however, data from only one controlled trial are available. Experience in the prevention of pre-eclampsia by prophylactic heparin is very limited, and in addition, data on pregnancy complications in women with known heritable thrombophilia or a history of thrombosis are inconsistent. These women will usually have a favorable pregnancy outcome referring to the European Prospective Cohort on Thrombophilia Study. In conclusion, thrombophilia screening might be justified in women with pregnancy loss and treatment with LMWH might be considered in those with pregnancy loss and thrombophilia. Further prospective studies and controlled interventional trials are urgently needed.

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.

Thrombophilia: implications for pregnancy outcome

There is growing evidence implicating congenital and acquired thrombophilias in the pathophysiological processes underlying miscarriage, intrauterine growth restriction (IUGR) and pre-eclampsia. Pregnancy itself is notably a hypercoagulable state, at least in part, due to the physiological changes in the coagulation and fibrinolytic systems; this has the potential for interaction with an acquired or heritable thrombophilia to cause adverse experiences. Recurrent fetal loss is associated with antiphospholipid antibody syndrome, procoagulant platelet microparticles and some inherited thrombophilias such as Factor V Leiden. There have been reports of both heritable and acquired thrombophilias being associated with pre-eclampsia, IUGR and abruption. However, these associations are not consistently reported with hereditary thrombophilias. The presence of thrombophilia might influence the severity of a condition such as pre-eclampsia, rather than cause it. The risk of fetal loss related to antiphospholipid syndrome can be reduced with antithrombotic therapy with heparin and low dose aspirin. Whether this extends to other thrombophilic conditions associated with adverse pregnancy outcome is not clear and further investigation is required. Screening for, and finding a, thrombophilic disease in patients with problems such as recurrent miscarriage, intrauterine death, intrauterine growth restriction and pre-eclampsia, may reflect an increased risk of venous thromboembolism (VTE).

Haemorheological adaptation during pregnancy in a Latin American population

OBJECTIVE

To investigate haemorheological changes during pregnancy in a Latin American population and compare to previously published data from Caucasian populations.

DESIGN

Cross-sectional study.

POPULATION

75 pregnant women at 10-36 wk of gestation and 17 non-pregnant female controls in Lima, Peru. All the women and their ancestors for three generations were born and lived at sea level.

METHODS

Viscosity, haematocrit and plasma fibrinogen, albumin and total protein concentrations were determined in blood samples obtained after an overnight period of fasting.

RESULTS

At 10 wk of gestation, total protein concentration and plasma viscosity were above non-pregnant levels by about 15% and subsequently decreased linearly with gestation. Fibrinogen concentration was increased in the first trimester; it then decreased to a nadir at about 20 wk and subsequently increased. Albumin concentration decreased linearly with gestation. Haematocrit decreased from pre-pregnancy levels at 10 wk to a nadir at about 26 wk. Blood viscosity increased in the first trimester and then decreased with gestation to a nadir at about 26 wk.

CONCLUSION

In the first trimester of pregnancy blood and plasma viscosity are increased and they subsequently fall with advancing gestation. Plasma viscosity reflects the changes in total protein concentration, and blood viscosity is dependent on the interplay of changes in plasma viscosity and haematocrit.

Plasminogen activator of urokinase type and its inhibitor of placental type in hypertensive pregnancies and in intrauterine growth retardation: possible markers of placental function

OBJECTIVE

Our purpose was to study the plasma concentrations of the plasminogen activator of urokinase type and its specific inhibitor of placental type in pregnancies complicated by hypertension or fetal growth retardation.

STUDY DESIGN

Consecutive patients with pregnancy-induced hypertension (n = 17), mild preeclampsia (n = 17), severe preeclampsia (n = 19), and intrauterine growth retardation (n = 19) were studied. Blood samples were obtained just before delivery (mean 2 days). Women with normal pregnancies (n = 40), longitudinally followed between the tenth and fortieth gestational weeks, served as a control group.

RESULTS

The plasma concentrations of the urokinase type antigen were significantly lower in women with severe preeclampsia or intrauterine growth retardation than those in women with normal pregnancies (p < 0.001). In all four groups with complicated pregnancies the antigen concentrations of the urokinase type and its inhibitor were significantly correlated with both placental weight and birth weight.

CONCLUSIONS

The plasma concentration of the urokinase type antigen would appear to reflect placental function, and both the antigen and its inhibitor concentrations are correlated with placental and fetal growth.

Fatal pulmonary embolism following spinal anaesthesia for caesarean section

Pulmonary embolism remains one of the commonest causes of maternal death. Regional blockade is reported to decrease the incidence of postoperative thrombo-embolic disease. We describe a case in which a fatal pulmonary embolism followed an emergency Caesarean section for which the patient was given a spinal anaesthetic. We believe it to be the first time this has been reported.

Superficial thrombophlebitis. II. Secondary hypercoagulable states

Secondary hypercoagulable states are complex clinical conditions associated with an increased risk of thrombosis in which the exact pathophysiology is poorly understood. Secondary causes of superficial thrombophlebitis include malignancy, pregnancy, use of oral contraceptives, infusion of prothrombin complex concentrates, Behçet's disease, Buerger's disease, Mondor's disease, infectious agents, conditions that promote venous stasis, intravenous catheters and intravenous drug use. Conditions that may stimulate superficial thrombophlebitis include dermatophyte cellulitis at saphenous phlebectomy sites, sarcoidal granulomas, cutaneous polyarteritis nodosa, and hyperalgesic pseudothrombophlebitis in patients who test positive for human immunodeficiency virus. The distinguishing features, clinical evaluation, treatment, and histologic characteristics of the various disorders are reviewed.

Fibrinolysis and factor XIII in women with spontaneous abortion

In the present study, parameters of the fibrinolytic system and factor XIII were determined in 26 women with spontaneous abortion and in 21 women with intact pregnancies to gain insight into the role of fibrinolysis in spontaneous abortion. Both groups of women did not significantly differ from each other in age or weeks of pregnancy. There were no differences in euglobulin lysis time (ELT), tissue plasminogen activator (t-PA) antigen, and plasminogen activator inhibitor type 1 (PAI-1) antigen between the study group and the control group. Factor XIII activity was significantly decreased in patients during abortion. In the present study, changes of fibrinolytic parameters measured in teh cubital vein blood of patients with abortion were not observed although local changes in fibrinolytic activity had been associated with spontaneous abortion. The pathophysiological role of the decrease in factor XIII activity observed in the present study remains to be elucidated.

Changes in coagulation and fibrinolysis during pregnancy: evidence of activation of coagulation preceding spontaneous abortion

In order to monitor physiological changes in coagulation and fibrinolysis that occur during normal pregnancy, blood samples were collected in each trimester of pregnancy from 17 volunteers. Control samples were collected from 12 non-pregnant female volunteers. As pregnancy advanced there was a rise in the basal levels of fibrinopeptide A, cross linked D-dimer fragment and the B beta 15-42 fragment and an increase in the in vitro rate of fibrinopeptide A generation. These results were consistent with an increased activation of coagulation during normal pregnancy, compensated for by a concomitant rise in fibrinolytic activity. In two patients who spontaneously aborted, evidence of uncompensated activation of coagulation could be detected before the manifestation of any clinical signs. In a second pregnancy in one of these patients similar changes were observed, but were reversed by heparin treatment and the pregnancy progressed to full-term delivery of a normal infant.

Acute coagulopathy in pregnancy

Pregnancy alters both the fibrinolytic system and coagulation cascade. In addition, pregnancy presents unique triggering mechanisms for DIC. Management of DIC in pregnancy should include removal of the triggering mechanism, blood, and factor replacement. Inherited coagulation defects, while rarely resulting in bleeding diathesis in the pregnant patient, do require monitoring of maternal factor levels. Genetic counseling should be offered to all patients with inheritable coagulation disorders.

Fibrinolysis during normal human pregnancy: complex inter-relationships between plasma levels of tissue plasminogen activator and inhibitors and the euglobulin clot lysis time

Although it has been previously considered that blood fibrinolytic capacity is reduced during pregnancy, this has been disputed. Also the mechanisms underlying any change in fibrinolysis in pregnancy require clarification. We have therefore measured the plasma activity of tissue plasminogen activator (t-PA) and inhibitors (t-PAi) and the concentration of the pregnancy specific inhibitor (PA12) antigen, as well as the euglobulin clot lysis time (ECLT) during normal pregnancy. Plasma concentrations of fibrinogen, plasminogen, fibrin(ogen) degradation products (FDP) and cross-linked products (D-dimer) were also monitored. We confirm a marked reduction of the fibrinolytic activity of the plasma euglobulin fraction from the second trimester, and a parallel reduction in t-PA and increase in t-PAi activities, with rapid return to non-pregnant levels post-partum. In contrast, PAI2, whilst undetectable in non-pregnant control plasma, was already measurable in the first trimester, increased through pregnancy, and remained at a high concentration up to at least 48 h post-partum. Fibrinogen and plasminogen concentrations rose progressively through pregnancy and FDP and D-dimer were frequently detectable in late pregnancy plasma. Changes in the ECLT and plasma t-PA and t-PAi activities in pregnancy cannot therefore be directly related to the concentration of PAI2 antigen. Also, despite the apparent marked reduction in fibrinolytic capacity fibrin(ogen) breakdown products are frequently present in increased plasma concentrations in late pregnancy.

Epidemiology and pathogenesis of venous thrombosis

Venous thrombi are intravascular deposits composed predominantly of fibrin and red blood cells with a variable platelet and leukocyte component. They frequently arise in large venous sinuses in the calf, in valve cusp pockets either in the deep veins of the calf or thigh or in venous segments that have been exposed to direct trauma. Venous thrombosis can be produced experimentally by a combination of stasis and systemic hypercoagulability or by stasis and endothelial damage. Thrombosis is augmented if the fibrinolytic mechanism is inhibited or defective. A number of clinical conditions and laboratory abnormalities are associated with and predispose to venous thrombosis and, in many of these, it is possible to identify one or more of the thrombogenic factors discussed. Venous thromboembolism (venous thrombosis and pulmonary embolism) is a serious and potentially fatal disorder that usually complicates the course of sick hospitalized patients, but occasionally affects ambulant and otherwise healthy individuals. Screening studies with iodine-125 fibrinogen leg scanning, impedance plethysmography and perfusion lung scanning have shown that the majority of venous thrombi and pulmonary emboli that occur in hospitalized patients are small and asymptomatic, and it is likely that most are clinically insignificant. In bedridden patients, most thrombi commence in the calf and are asymptomatic. When a calf vein thrombus extends into the proximal venous segment, the risk of clinically significant pulmonary embolism increases. Less is known about the incidence and clinical significance in a nonhospital population; although asymptomatic disease occurs, its frequency is unknown. In contrast to the patients with asymptomatic venous thrombosis, symptomatic patients with venous thrombosis usually have large occulsive thrombi localized in their proximal veins.

Postpartum acute renal failure in a drug addict

Renal diseases occur in intravenous drug abusers, especially heroin addicts, in the form of interstitial nephritis, nephrotic syndrome or acute renal failure due to rhabdomyolysis. We report a case of acute renal failure not ascribable to rhabdomyolysis nor to the main pathogenetic mechanisms of pregnancy-related acute renal failure in a pregnant heroin addict woman after vaginal delivery following uncomplicated pregnancy. Drug-related immunological abnormalities and microcirculatory distress may be involved.

An epidemic of maternal thrombocytopenia associated with elevated antiplatelet antibody. Platelet count and antiplatelet antibody in 116 consecutive pregnancies: relationship to neonatal platelet count

Twenty-eight (24%) of 116 pregnant women studied prospectively during an 8-month period in 1983 had platelet counts of less than 150,000/mm3 at least once during pregnancy. Thirteen of these were thrombocytopenic in both the prenatal and the peripartum period. Eighteen were restudied 3 to 12 months after delivery. One woman, who was pregnant again, had a platelet count of 140,000/mm3. In the others, platelet counts were in the normal range. Platelet-associated immunoglobulin G and serum antiplatelet antibody levels were elevated in 79% and 61%, respectively, of these 28 women on at least one occasion. However, 59% of 73 pregnant nonthrombocytopenic women had increased platelet-associated immunoglobulin G levels and 59% had positive serum antiplatelet antibody test results. Twenty women who had increased platelet-associated immunoglobulin G levels and positive serum antiplatelet antibody test results were normal 6 to 10 months after delivery. Of 105 infants studied, 10 were thrombocytopenic. Neonatal thrombocytopenia was not predicted by maternal platelet count, platelet-associated immunoglobulin G, or serum antiplatelet antibody. By the fall of 1984, the incidence of thrombocytopenia had dropped to two in 280 consecutive pregnancies. We conclude that (1) epidemics of thrombocytopenia can occur in pregnant women and (2) if a women is found to be thrombocytopenic for the first time during pregnancy, she should not be subjected to the measures advocated for the management of pregnancy in women with autoimmune thrombocytopenic purpura.

Platelet values during normal pregnancy

Blood samples were obtained from 26 healthy women at regular intervals throughout pregnancy and analysed using a Coulter Counter Model S Plus III. The mean values for the various haematological indices at each stage of gestation were first calculated; the platelet count showed a small decrease throughout pregnancy as did haemoglobin concentration while there was an apparent increase in mean platelet volume, platelet distribution width and white cell count. However, analysis of the trends within patients did not always reflect these mean changes; there was considerable variation in platelet count within individuals and the apparent fall in the group as a whole was accounted for by a considerable fall in a few individuals. The assumption that the trends in platelet values determined from groups of patients will indicate how individual pregnant women behave is misleading.

The fibrinolytic system in man

The existence of a system in the human body capable of inducing the dissolution of endogenous pathologically formed thrombi was appreciated in ancient times. Considered in detail in this article are the data that have elucidated the physiologic regulation of which plasmin formation is dependent on, the plasma concentration of plasminogen, availability of activators of plasminogen in the plasma and surrounding tissue environment, the concentration of naturally present inhibitors, and the existence of fibrin in the circulation. Important in this rapidly progressive scientific discipline is consideration of the factors which control the synthesis of the components of this proteolytic enzyme system. Recently abundant information has indicated that this plasminogen-plasmin proteolytic enzyme system can be utilized therapeutically. Knowledge of the mechanisms of this system has permitted identification of agents that can be exogenously administered to releave thrombotic obstruction to blood flow in the venous (pulmonary emboli, deep vein thrombosis) and arterial (peripheral and central vessels) circulatory systems. Particularly important is the demonstration that thrombolytic agents can directly attack and alleviate the immediate cause of acute myocardial infarction. As a result of the innovations in the present decade, it is evident that the plasminogen system can be advantageously employed to reverse the pathologic effects of all thrombotic diseases.

Blood rheology

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Blood clotting and fibrinolysis in pregnancy

During normal pregnancy, the concentrations of many of the clotting factors rise, thereby increasing the potential to generate fibrin. There is also evidence of increased thrombin activity during normal pregnancy which sharply increases during placental separation. Antithrombin III, the main inhibitor of thrombin and activated factor X, shows no compensatory rise during pregnancy but increases during the puerperium. Plasminogen and antiplasmin concentrations rise during pregnancy but systemic fibrinolytic activity, as measured by the euglobulin lysis time, is markedly depressed during pregnancy; the reduced fibrinolytic activity returns to non-pregnant values very soon after delivery. The loss of fibrinolytic activity is presumed to be loss of plasminogen activator, because when this is added in excess in the urokinase sensitivity test, the fibrinolytic response is normal. The capacity for localized fibrinolytic activity is not lost, however, because fibrinolytic degradation products are slightly raised during pregnancy. The overall pattern is one of increased coagulant and reduced fibrinolytic capacity during pregnancy which may protect the pregnant woman against the haemostatic challenge of placental separation.

Whole-blood fibrinolytic activity in normal and hypertensive pregnancies and its relation to the placental concentration of urokinase inhibitor

Whole-blood fibrinolytic activity was measured in 68 pregnant and 29 nonpregnant women with a sensitive, solid-state assay in which 125I-labeled fibrin was bound to polystyrene tubes. Antepartum fibrinolytic activity in 36 normotensive gravid women [234.5 +/- 29.2 (mean +/- standard error of the mean) ng fibrin lysed/30 min] was significantly (p less than 0.001) greater than that found in 28 nonpregnant normotensive women not taking oral contraceptives (63.61 +/- 7.66 ng fibrin lysed/30 min) and not different from the activity observed during the active phase of labor (198.50 +/- 16.5 ng fibrin lysed/30 min.) Normotensive pregnant patients had a significant (p less than 0.001) increase in whole-blood fibrinolytic activity (341.04 +/- 25.7 ng fibrin lysed/30 min) within the first 24 hours after delivery which persisted in measurements taken the second postpartum day. Fibrinolytic activity values before labor, in the active phase of labor, and in the first and second postpartum days in 17 patients with mild to moderate pregnancy-induced or pregd or pregnancy-aggravated hypertension were not different from those found in the normotensive group. However, patients with severe pregnancy-induced or pregnancy-aggravated hypertension had significantly (p less than 0.01) lower levels of fibrinolytic activity than normotensive patients before labor, during the active phase of labor, and on the first and second postpartum days. The placental 800 X g and 110,000 X g fractions of patients with severe hypertension had a significantly (p less than 0.001) greater capacity to inhibit "in vitro" urokinase-induced fibrinolysis than similar fractions obtained from placentas of normotensive women, and there was a significant inverse correlation (r = 0.61; p less than 0.01) between whole-blood fibrinolytic activity and urokinase inhibition by placental fractions. Our findings indicate that contrary to widely held views, fibrinolysis is extremely active in term pregnancies and during labor and that a derangement of this activity is present in cases of severe pregnancy-induced or pregnancy-aggravated hypertension.

The comparative effects of a synthetic and a 'natural' oestrogen on the haemostatic mechanism in patients with primary amenorrhoea

A synthetic and a natural oestrogen were administered alternately for three months to nine women with primary amenorrhoea using a randomized cross-over schedule. Measurements of haemostatic function were performed before and at the end of each treatment period. No significant change in haemostatic function was observed after treatment with the 'natural' oestrogen, oestriol succinate. In contrast, treatment with a synthetic oestrogen, ethinyloestradiol, caused shortening of the prothrombin time and an increase in plasma concentration of factor VII and plasminogen. These data support other observations in suggesting that natural oestrogens may have fewer potentially adverse effects on haemostatic function than synthetic oestrogen.

The effects of long-term therapy with oestriol succinate on the haemostatic mechanism in postmenopausal women

In a previous report we showed that oestriol succinate administered to postmenopausal women caused fewer changes in haemostatic function over a four-month period than ethinyloestradiol. Potential longer-term effects were studied in postmenopausal women treated for osteoporosis with oestriol succinate for up to 12 months. Over this period there was no significant change in concentration of plasma coagulation factors, an increase in plasminogen concentration and euglobulin lysis activity, and an inconsistent increase in platelet sensitivity to aggregation induced by ADP and collagen. The relative lack of effect of oestriol succinate on coagulation function is encouraging with regard to the future incidence of thromboembolic complications of therapy.

Components of the haemostatic mechanism in twin pregnancy

Components of the haemostatic mechanism were measured at intervals throughout pregnancy in 11 patients with twins and compared with a group of 21 patients with singleton pregnancies. Mean plasma fibrinogen levels were consistently (but not significantly) elevated in the mothers of twins while other parameters showed no differences.

Arterial blood gases in pre-eclampsia

Arterial blood gases, physiological dead space and percentage pulmonary venous admixture (physiological shunt) were measured in 31 patients with proteinuric pre-eclampsia. There was no difference in pulmonary function in 22 patients with moderate pre-eclampsia when compared with normal pregnancy, but in 9 patients with severe pre-eclampsia, there was a significant increase in alveolar-to-arterial PO2 difference and physiological shunt, indicating a degree of pulmonary ventilation/perfusion imbalance. There was no accompanying hypoxaemia, suggesting that the impairment was of no clinical importance.