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Haematological disorders
Published in Judy Bothamley, Maureen Boyle, Medical Conditions Affecting Pregnancy and Childbirth, 2020
Normal pregnancy is associated with alterations in the proteins of the coagulation and fibrinolytic systems, resulting in a relative state of hypercoagulability1. These changes ensure the effective control of bleeding in the third stage of labour. Pro-coagulant factors, such as Von Willebrand factor, factor VII, factor VIII, factor X and fibrinogen enhance thrombin production in pregnancy53,1. In addition, an acquired resistance to the anticoagulant protein C and a reduction in protein S further contribute to the increased coagulability. Impaired fibrinolysis, resulting in slower breakdown of clots, also occurs54,1.
Transfusion products
Published in Jennifer Duguid, Lawrence Tim Goodnough, Michael J. Desmond, Transfusion Medicine in Practice, 2020
Recombinant human activated protein C has emerged as a new drug for treating severe sepsis in intensive care patients. Activated protein C is a potent antithrombotic serine protease with substantial anti-inflammatory properties. Pro-inflammatory cytokines released in response to infection can also activate coagulation and inhibit fibrinolysis. A combination of procoagulant and inflammatory stimuli provides a potent mechanism for initiating and perpetuating microvascular injury, intravascular coagulation, inadequate tissue perfusion, and organ failure. Activated protein C inhibits activated factors V and VIII, stimulates fibrinolysis, reduces production of tumour necrosis factor a by monocytes, and reduces interactions between neutrophils and endothelial cells.
Thrombosis in Children
Published in Hau C. Kwaan, Meyer M. Samama, Clinical Thrombosis, 2019
Eric F. Grabowski, Margaret W. Hilgartner
Walker39 made the observation that protein S serves as a cofactor for the anticoagulant effects of protein Ca. Protein S is not converted to a serine protease, making it unique among the vitamin K-dependent coagulation factors. Its role, if any, with respect to the profibrinolytic effect of protein Ca is unknown. Clinical manifestations of protein S deficiency are similar to those for protein C deficiency: recurrent venous thrombosis, pulmonary embolism, and superficial thrombophlebitis. Both heterogygous and homogygous40 forms of the deficiency exist, although fewer overall cases have been identified as compared to protein C deficiency. Patients with protein S deficiency and thrombosis respond to intravenous heparin, followed by oral anticoagulation therapy.
Postpartum spontaneous renal blood vessel rupture followed by pulmonary artery thromboembolism associated with protein C deficiency
Published in Journal of Obstetrics and Gynaecology, 2019
A 33-year-old primipara woman presented to our antenatal clinic at 5 weeks of gestation. Her previous three pregnancies had all resulted in miscarriages. At her initial visit, a detailed evaluation for a recurrent foetal loss was performed and the laboratory results revealed PCD. The value of her plasma protein C was 52% (normal: 70–130%). The other antenatal laboratory findings were within the normal ranges. On the diagnosis of a PCD, we planned to anticoagulate her with low-molecular-weight subcutaneous heparin (LMWH) and a low-dose aspirin (LDA), daily. The patient’s antenatal course was unremarkable. LMWH was continued until 28 weeks of gestation and LDA was continued until 36 weeks of gestation. A caesarean section was performed at 38 + 6 weeks of gestation due to cephalopelvic disproportion, and a healthy female infant weighing 2.58 kg was delivered. The caesarean section’s estimated blood loss was within the normal range. On postoperative day (POD) 1, the patient’s haemoglobin (Hb) was 11.3 g/dL, without a transfusion. The postoperative course was uneventful and a postpartum anticoagulation therapy was not administered.
Aetiology of recurrent miscarriage and the role of adjuvant treatment in its management: a retrospective cohort review
Published in Journal of Obstetrics and Gynaecology, 2018
Samuel James Alexander Dobson, Kanna Mannadiar Jayaprakasan
As per the RCOG (Regan et al. 2011), screening investigations were performed as follows. Inherited thrombophilia was excluded by screening for Factor V Leiden mutation, antithrombin 3 deficiency and protein S deficiency. In this study, the clinicians involved also screened for protein C deficiency and hyperhomocysteinaemia. While these are not recommended tests by the RCOG, they are recognised as causes of systemic thrombosis and as such have been included. Antiphospholipid syndrome was confirmed with two positive tests for lupus anticoagulant, Beta-2 Glycoprotein antibodies or anticardiolipin antibodies (IgM and/or IgG titres above the 99th percentile or of >40 g/L or >40 ml/L) 12 weeks apart (Regan et al. 2011). Where available, karyotyping was obtained both from products of conception of the third or subsequent miscarriage and from peripheral blood karyotyping in the parents if miscarriage tissue was found to have an abnormal karyotype. Pelvic ultrasound was used to screen for uterine abnormalities. 3 D ultrasound or MRI was done to classify uterine anomalies correctly, if conventional 2 D scan was suggestive of an anomaly. Our units also offered screening for thyroid disorders and thyroid peroxidase antibodies only as part of the TABLET trial.
Disseminated intravascular coagulation: an update on pathogenesis and diagnosis
Published in Expert Review of Hematology, 2018
Marcel Levi, Suthesh Sivapalaratnam
Activated protein C is responsible for proteolytic degradation of the pivotal coagulation cofactors Va and VIIIa and is thereby another important regulator of thrombin generation. The conversion of protein C to activated protein C occurs after thrombin binds to endothelial thrombomodulin [43]. This process is importantly potentiated by binding of protein C to the endothelial protein C receptor (EPCR) [44]. In DIC, there is a significant cytokine-mediated downregulation of both thrombomodulin and EPCR, which causes reduced protein C activation. The downregulation of thrombomodulin also affects the clearance of thrombin, as thrombomodulin has a very high affinity for free thrombin. As activated protein C exerts also a series of anti-inflammatory effects, reduced formation of activated protein C may also seriously affect endogenous anti-inflammatory pathways. In observational clinical studies reduced plasma concentrations of protein C were associated with a higher risk of death [45]. Abrogation of protein C activation by various interventions increased mortality in baboons challenged with live bacteria [46,47]. In contrast, administration of activated protein C resolved the coagulopathy and improved survival in these experiments. Based on these findings, it seems that activated protein C is of pivotal relevance in the regulation of DIC.