Coagulation disorders: an overview
The approach to a bleeding patient starts by using the bleeding pattern, the platelet count, and the PT/aPTT to localize the defect to primary hemostasis (platelets or von Willebrand factor), secondary hemostasis (coagulation factors), or a combined process such as DIC or liver disease. A mixing study then separates a factor deficiency, which corrects, from an inhibitor, which does not, and directs the specific factor or von Willebrand assay that confirms the diagnosis.
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What this article covers
- Overview
Framework: hemostasis has a primary phase, in which platelets adhere via von Willebrand factor (vWF) and aggregate into a plug, and a secondary phase, in which coagulation factors generate thrombin…
- Epidemiology
Hemophilia A is more common than hemophilia B; both are X-linked recessive and rare, so nearly all affected patients are male (hemophilia A).
- Risk factors
Bleeding pattern and family history: prior surgical/dental bleeding, menorrhagia, and a family history of bleeding raise pretest probability for a hereditary defect.
- Pathophysiology
Primary hemostasis: platelets adhere via vWF bridging glycoprotein Ib to exposed collagen, then aggregate via glycoprotein IIb/IIIa; a defect here causes immediate, superficial bleeding because the initial plug never forms or is unstable.
- Clinical features
Primary hemostasis pattern: mucocutaneous bleeding with immediate onset at injury; petechiae, ecchymoses, epistaxis, gingival bleeding, menorrhagia; petechiae and mucosal bleeding become common below a platelet count of 20,000/microL.
- Differential diagnosis
Disseminated intravascular coagulation: thrombocytopenia, prolonged PT and aPTT, low fibrinogen, markedly elevated D-dimer, critically ill patient (DIC).
- Diagnosis
Establish the localization by pattern plus the screening panel, not any single test: combine bleeding history with a CBC and platelet count, PT/INR, and aPTT; which tests are abnormal sets the differential and the next step.
- Management
Treat life-threatening bleeding first: IV access and crystalloid resuscitation, hold antiplatelet and anticoagulant drugs, send screening labs before empiric blood products in an unstable patient.
- Complications
Hemophilic arthropathy: recurrent hemarthrosis causes chronic synovitis and joint destruction of the knees, ankles, and elbows, a major cause of disability in undertreated hemophilia.
- Prognosis
Prognosis tracks the specific diagnosis: hereditary factor deficiencies on regular replacement and mild von Willebrand disease treated with desmopressin have a good long-term outlook; DIC and severe…
- Prevention
Prophylactic factor replacement in severe hemophilia: scheduled recombinant factor VIII or IX infusions two to three times weekly, individualized to trough level and bleeding phenotype, prevent…
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Related articles
- Hemophilia A
Hemophilia A is an X-linked recessive deficiency of factor VIII that produces deep bleeding into joints, muscles, and after surgery in male patients, diagnosed by an isolated prolonged aPTT that corrects on a mixing study and confirmed by a reduced factor VIII activity assay. Management is factor VIII replacement or emicizumab for moderate to severe disease, desmopressin for mild disease, and antifibrinolytics for mucosal bleeding, with inhibitor development the most serious treatment complication.
- Von Willebrand disease
Von Willebrand disease is the most common inherited bleeding disorder, caused by deficient or dysfunctional von Willebrand factor, producing mucocutaneous bleeding from impaired platelet adhesion plus a mild secondary factor VIII deficiency. Diagnosis rests on the vWF antigen, ristocetin cofactor activity, and factor VIII activity panel, and management centers on desmopressin for type 1, vWF concentrate for severe or desmopressin-unresponsive disease, and antifibrinolytics for mucosal bleeding.
- Disseminated intravascular coagulation
Disseminated intravascular coagulation is a secondary, systemic activation of coagulation and fibrinolysis, most often from sepsis, that simultaneously consumes platelets and clotting factors, causing microvascular thrombosis and bleeding. Diagnosis rests on a laboratory constellation, thrombocytopenia, prolonged PT and aPTT, low fibrinogen, and elevated D-dimer, in a predisposing clinical setting, and management centers on treating the underlying trigger while replacing blood components only for active or high-risk bleeding.
- Platelet disorders
Platelet disorders span a quantitative axis (thrombocytopenia from decreased production, increased destruction, or sequestration) and a qualitative axis (normal-count platelets that fail to adhere or aggregate), plus reactive or clonal thrombocytosis, and all present with mucocutaneous bleeding rather than deep hematomas. Diagnosis starts with a platelet count and smear to exclude pseudothrombocytopenia, adds platelet function testing when the count is normal but bleeding is mucocutaneous, and management is cause-directed.
- Thrombocytopenia: an overview
Thrombocytopenia, a platelet count below 150,000/microL, is a laboratory finding rather than a single disease, so evaluation starts with the smear to exclude pseudothrombocytopenia and identify the can't-miss consumptive emergencies TTP, HIT, and DIC before working through production, destructive, and sequestration causes. Management treats the underlying cause, reserves platelet transfusion for bleeding or procedural thresholds, and specifically avoids platelet transfusion in TTP and HIT except for life-threatening hemorrhage.
- Anticoagulants
Anticoagulants are drugs that block steps in the coagulation cascade to prevent or treat venous thromboembolism, cardioembolic stroke, and valve thrombosis. Direct oral anticoagulants are first-line for most nonvalvular indications, while warfarin, titrated to an INR of 2 to 3, remains required for mechanical valves and high-risk antiphospholipid syndrome; parenteral heparins bridge and cover renal failure or urgent reversal needs.