Seminars in thrombosis and hemostasis
-
During normal pregnancy the hemostatic balance changes in the direction of hypercoagulability, thus decreasing bleeding complications in connection with delivery. The most important initial factor for acute hemostasis at delivery is, however, uterine muscle contractions, which interrupt blood flow. Global tests such as Sonoclot signature, the Thromboelastogram, and a new method analyzing overall plasma hemostasis, all show changes representative of hypercoagulability during pregnancy. ⋯ Platelet count and free protein S, however, can be abnormal longer. Hemostasis should not be tested earlier than 3 months following delivery and after terminating lactation to rule out influences of pregnancy. PAI-1 and PAI-2 levels decrease fast postpartum, but PAI 2 has been detected up to 8 weeks postpartum. alpha 2 -antiplasmin, urokinase, and kallikrein inhibitor levels have been reported to be increased 6 weeks postpartum.
-
Semin. Thromb. Hemost. · Dec 2002
Coagulation index to distinguish severe preeclampsia from normal pregnancy.
The purpose of this study was to establish a new coagulation index to distinguish severe preeclampsia from normal pregnancy using optimal coagulation parameters. The difference between platelet counts in early gestation and before delivery (DeltaPlt = [platelet counts before delivery] - [platelet counts in early gestation]) was calculated as an index of changes in platelet counts. Antithrombin (AT) activity, thrombin-antithrombin (TAT) complex, fibrin degradation products (FDP) D-dimer, and DeltaPlt were investigated in 72 cases of normal pregnant women in the third trimester of pregnancy and 56 cases of severe preeclampsia. ⋯ Among patients with severe preeclampsia, coagulation and fibrinolysis disorders before delivery were typical in patients terminated by cesarean section (coagulation index = 1.62 +/- 1.66) compared with those with successful vaginal delivery (coagulation index = 0.52 +/- 0.34) (p < 0.05). These facts suggest that an excessive hypercoagulable state is associated with the termination of pregnancy resulting from the aggravation of preeclampsia. From the viewpoint of coagulation and fibrinolysis disorders, the predictive value in order to decide the optimal time for the termination of pregnancy could be recommended when the coagulation index exceeded 1.20.
-
Semin. Thromb. Hemost. · Dec 2002
ReviewVenous thromboembolic risk and its prevention in hospitalized medical patients.
In medical patients, the risk of venous thromboembolism (VTE) is substantially underestimated and prophylaxis is used far less than in surgical patients, reflecting the scarcity of evidence supporting antithrombotic therapy in nonsurgical settings. However, current consensus documents recommend assessment of all medical, as well as surgical, patients for thromboembolic risk and provide prophylaxis recommendations according to the risk level, determined by the presence of different clinical and molecular risk factors. Although long-term, underlying clinical and molecular risk factors also have a major impact on overall risk in medical patients; risk clearly varies with the type of medical condition. ⋯ Emerging evidence has led to a grade 1A recommendation for the use of thromboprophylaxis in these patients in the most recent consensus conference on thromboprophylaxis. Further studies, however, are required to clarify the optimal duration of prophylaxis in medical patients and to evaluate the potential role of outpatient prophylaxis. Accurate risk assessment and prompt implementation of appropriate prophylaxis, selected on the basis of evidence from well-designed controlled clinical trials, may reduce the future morbidity and mortality due to VTE in medical patients.
-
Heparin-induced thrombocytopenia (HIT), a serious side effect of heparin treatment, requires alternative anticoagulation in most affected patients. The recombinant hirudin (r-hirudin) lepirudin has been approved for this purpose after two prospective trials in laboratory-confirmed HIT patients. Other drugs available for this purpose are danaparoid sodium (a heparinoid) and argatroban, a synthetic direct thrombin inhibitor. ⋯ Antihirudin antibodies, which can alter the pharmacokinetics as well as the pharmacodynamics of hirudin, can also be countered by close monitoring and appropriate dose adjustments. Whereas hirudins have not yet managed to gain importance in non-HIT indications such as unstable coronary syndromes, they have a major role to play in the treatment of HIT. The choice between the available drugs for HIT, namely lepirudin, danaparoid, and argatroban, has to be made according to the clinical presentation of the patient.
-
Semin. Thromb. Hemost. · Jun 2002
Venous thromboembolism epidemiology: implications for prevention and management.
Venous thromboembolism is a major health problem, with an incidence that exceeds 1 per 1000. Over 200,000 new cases occur in the United States annually. Of these, 30% of patients die within 30 days; one-fifth suffer sudden death due to pulmonary embolism. ⋯ Independent predictors for recurrence include increasing age, obesity, malignant neoplasm, and extremity paresis. About 28% of patients develop venous stasis syndrome within 20 years. To reduce venous thromboembolism incidence, improve survival, and prevent recurrence and complications, patients with these characteristics should receive appropriate prophylaxis.