Bleeding vs Coagulation Disorders PDF

Bleeding Vs coagulation disorder By Dr. Himani Rai Moderator: Dr. Manish Sulya DEPT OF PATHOLOGY, GMC BHOPAL Hemostasis Hemostasis is a regulated process by which blood is maintained in liquid state inside the vessels, yet arrests bleeding at the site of vascular injury by forming a hemostatic c...

Bleeding Vs coagulation disorder By Dr. Himani Rai Moderator: Dr. Manish Sulya DEPT OF PATHOLOGY, GMC BHOPAL Hemostasis Hemostasis is a regulated process by which blood is maintained in liquid state inside the vessels, yet arrests bleeding at the site of vascular injury by forming a hemostatic clot. Thrombosis is a pathological counterpart of hemostasis in which blood clot (thrombus) is formed inside the circulation. Components of normal hemostasis and thrombosis: Five components namely: Platelets, Blood vessel wall (endothelium), Coagulation system, Coagulation regulatory system and Fibrinolytic system participate both in hemostasis and thrombosis. 1.Platelets: anuclear cellular fragments derived from bone marrow megakaryocytes Electron microscopy: several glycoprotein receptors, two types of cytoplasmic granules and a contractile cytoskeleton. Glycoprotein receptors: ◆ Glycoprotein (Gp) IIb-IIIa: main receptor on cell surface. ◆ Glycoprotein Ib-IX: receptor for binding vWF with platelets. Cytoplasmic granules ◆ Alpha (α) granules ◆ Dense granules Contractile cytoskeleton: dense microtubules and circumferential microfilaments, which maintain the disk shape of platelets. Role of Platelets in Hemostasis: • Form the primary hemostatic plug. • Release platelet activating and procoagulant molecules. • Provide a procoagulant surface for the activation of coagulation system. • 2)BLOOD VESSEL WALL • Endothelial Cells 3 antithrombotic systems to limit coagulation. (1) Antithrombin III (2) Protein C and protein S (3) Tissue factor pathway inhibitor (TFPI). Injured endothelium or under inflammatory conditions, it downregulates its anticoagulant functions and becomes procoagulant. Injury to endothelial cells or endothelial activation exposes highly thrombogenic subendothelial extracellular matrix (ECM), which leads to platelet adherence and activation. 3)COAGULATION SYSTEM • two pathways namely extrinsic and intrinsic. Prothrombin time (PT) : assesses the function of the coagulation factors involved in the extrinsic pathway (factor VII) and common pathway (factors X,II, V and fibrinogen). PT is performed by adding tissue factor. Partial thromboplastin time (PTT)/activated partial thromboplastin time (APTT) :assesses the function of the coagulation factors utilized in the intrinsic pathway (factors XII, pre-K, HMWK, XI, IX and VIII) and common pathway (factors X, V, II and fibrinogen). PTT is initiated by adding negatively charged particles like glass beads. 4)COAGULATION REGULATORY MECHANISM: a)Antithrombin: Inhibits the activity of thrombin and factors IXa, Xa, XIa and XIIa. b)Proteins C and S:vitamin K dependent proteins C)Tissue factor pathway inhibitor (TFPI): TFPI is a protein which inactivates tissue factor—factor VIIa complexes and inactivates factor VII 5)Fibrinolytic system: Plasminogen activated either by: 1) A factor XII–dependent pathway 2) Plasminogen activators (PAs): tissue plasminogen activator (t-PA) secreted by endothelial cells and others include urokinase. Interactions among coagulation, coagulation regulatory and fibrinolytic system Different steps in hemostasis DISORDERS OF HEMOSTASIS Functions of hemostasis: To arrest bleeding at the site of injury or blood loss by forming a hemostatic plug. To remove the hemostatic plug when healing is complete. To maintain blood in a fluid state within the vascular system. Normally, a delicate balance exists between the different hemostatic functions mentioned above .A deficiency or exaggeration of any one of the components of hemostasis may lead: Failure to restore the integrity of an injured vessel causing bleeding (hemorrhage) OR Inability to maintain the fluidity of blood causing thrombosis. Bleeding disorders are more common than thrombotic disorders. Classification of Hemostatic Disorders Terminologies Used in Bleeding Disorders 1. Petechiae: small (1 to 2 mm in diameter) red to purple hemorrhagic spots in the skin, mucous membranes or serosal surfaces. Result from blood leaking through endothelial lining of capillaries. Commonly with low platelet counts (thrombocytopenia) or defective platelet function. 2. Purpura: purpura means purple. slightly larger (>3 mm) than petechiae. Causes: thrombocytopenia, increased vascular fragility and vasculitis 3. Ecchymoses: larger (>1–2 cm) from blood escaping through endothelium into intact subcutaneous tissue 4. Hematoma: when blood leaks from a vessel and collects within a tissue. blue or purple and slightly raised. 5. Easy bruisability: term used when petechiae and ecchymoses develop with less than usual trauma. Laboratory Evaluation of Hemostatic and Thrombotic Disorders Laboratory tests in bleeding disorders TESTS FOR PLATELET COMPONENT Platelet Count : either manually or by electronic counters. Normal range: 1,50,000–4,50,000 platelets/cu mm Platelet Aggregation Test: Principle: measure the ability of platelets to aggregate in response to agonists like thrombin and form the basis for qualitative tests of von Willebrand factor. Use: For classification of congenital qualitative disorders of platelets. Clot Retraction Test: Principle: After the coagulation of blood, the clot under the action of thrombasthenin (a substance released from platelets) undergoes contraction and starts retracting within one hour. Process completed in 18–24 hours with separation of serum. Clot retraction is dependent on normal platelet number, platelet function, concentration of fibrinogen and the activity of the fibrinolytic pathway. Normal value: Normal clot retraction shows more than 50% of serum separated at the end of 24 hours. A normal clot is firm, rubbery, elastic and not easily broken. Interpretation: Absent or reduced clot retraction is seen in: • Fibrinogen deficiency (congenital or acquired) • Thrombocytopenia • Thrombasthenia. TESTS FOR PLATELET AND VASCULAR COMPONENT Capillary Fragility (Hess/Tourniquet) Test: Principle: measures the ability of capillaries to withstand the increased stress. Normal Range: About 0–5 petechiae. Interpretation: Positive test is indicated by more than 10 petechiae and is found in: • Vessel wall abnormalities: Vascular purpura ,Scurvy • Platelet disorders: – Thrombocytopenia – Defective platelet function Bleeding Time: Used as screening test for disorders of platelet-vessel wall interactions. Measures the time required for bleeding to stop after a standardized superficial cut of the skin capillary bed. Methods • Duke’s method-obsolete • Ivy’s method • Template method (method of choice). Template Method for Bleeding Time: Principle: A small skin cut of a standard size and depth is made and the oozing blood is wiped with a filter paper. Bleeding stops when the capillaries contract and platelet plug seals the vessel. Normal range: About 2–9 minutes. Interpretation: Prolonged bleeding: • Platelet disorders • Primary vascular disorders: Ehlers-Danlos syndrome. • Platelet-vessel wall interactions: von Willebrand disease. • Others: Afibrinogenemia, severe hypofibrinogenemia, uremia, aspirin. BLEEDING DISORDERS CAUSED BY VESSEL WALL ABNORMALITIES Vascular purpura :group of disorders of blood vessels which result in bleeding(sometimes called nonthrombocytopenic purpura). Relatively common disorders. Usually do not cause serious bleeding induce small hemorrhages (petechiae and purpura) in the skin or mucous membranes. Platelet count, bleeding time and results of the coagulation tests (PT, PTT) are usually normal Hess test is usually positive. Acquired Disorders I)Decreased connective tissue: • Collagen is required for the support of the blood vessel wall. Any impairment in collagen formation may result in bleeding from the microvasculature. 1)Senile purpura: Age-related atrophy of supporting connective tissue of blood vessels. Superficial, sharply demarcated, persistent purpuric spots on the forearms and other sunexposed areas of the skin. 2)Scurvy: Microvascular bleeding resulting from impaired formation of collagens. 3)Cushing syndrome and steroid therapy: loss of perivascular supporting tissue. • II)Vasculitis: Inflammation of small blood vessels is known as vasculitis Due to the immune complexes that attach either to the endothelial cells or the subendothelial matrix. 1)Henoch-Schönlein purpura (HSP):  Systemic hypersensitivity disease of unknown etiology.  Due to the deposition of circulating immune complexes within vessels.  characterized by purpura, abdominal pain (due to bleeding into the gastrointestinal tract), arthralgia and acute glomerulonephritis.  Microscopic examination of blood vessel shows leukocytoclastic vasculitis with perivascular infiltration of neutrophils and eosinophils. Blood picture: Moderate polymorph leucocytosis and occasionally a mild eosinophilia. ESR: moderately increased. Platelet count, bleeding time & coagulation screening tests : Normal. Tourniquet test : moderately positive (about 25 per cent of cases). 2)Infections: Hemorrhage in the form of petechiae and purpura, especially meningococcemia, septicemia, infective endocarditis and rickettsioses. Mechanisms: Invasion of vessel, septic emboli, immune complex vasculitis or result of disseminated intravascular coagulation (DIC). 3)Drug reactions: Cause petechiae and purpura without thrombocytopenia. Mechanisms: • Drug-induced antibodies • Deposition of immune complexes in the vessel walls III)Associated with plasma cell dyscrasias : Amyloidosis: • Perivascular deposition of amyloid weaken the blood vessel wall and cause purpura. • most commonly seen in plasma cell neoplasms • presents as mucocutaneous petechiae. IV)Miscellaneous: Simple easy bruising: • purpuric lesions seen usually in women. • Bruises appear spontaneously on arms and legs and resolve rapidly. Hemostatic tests are within normal range. Inherited Disorders 1)Hereditary Hemorrhagic Telangiectasia (Weber-OslerRendu Syndrome)  Autosomal dominant disorder  Vascular malformation  Dilated, tortuous, thin-walled blood vessels of the skin & mucous membranes.  Bleed easily in to the mucous membranes of the nose (epistaxis), tongue, mouth and eyes and GIT. Blood picture: Anaemia proportional to the severity of the bleeding. Hypochromic microcytic anaemia of iron deficiency. Platelet count and tests of coagulation: Normal. Tourniquet test & bleeding time : Normal 2)Ehlers-Danlos Syndrome • Congenital disorder • Defective collagen synthesis • joint hypermobility skin laxity • easy bruising. • capillaries are poorly supported by subendothelial collagen and result in bleeding mainly in the form of ecchymoses. Abnormalities of Platelets • Platelet disorders are classified as Quantitative (number of platelets) or Qualitative (platelet function) in nature. Thrombocytopenia Platelet count <100 x 109/L. Sites of bleeding Cutaneous bleeding: In the form of petechiae, ecchymoses easy bruising and hemorrhages. Mucosal bleeding: gum bleeding, epistaxis and hematuria. Also melena or menorrhagia. Central nervous system: Intracranial bleed rare. Causes of thrombocytopenia Idiopathic (Immune) Thrombocytopenic Purpura • Primary or essential thrombocytopenic purpura, purpura haemorrhagica, Werlhofs disease. • Platelets get coated by antibodies and those platelets are destroyed by mononuclear phagocytic system in the spleen. • In ITP, autoantibodies are directed against the surface glycoprotein Ib/IX or Ilb/IIIa. • Antiplatelet antibodies also bind to megakaryocytes affecting platelet production. • Platelet count < 100 x 109/L threshold for diagnosis. ACUTE ITP • Self-limited disease • children between 2 and 4 years • equal frequency in both sexes. • Often presents 1–3 weeks after viral (measles, rubella, EBV) infection. • Platelet destruction caused by antiplatelet autoantibodies( IgM type). • Platelet count is decreased (can be below 10,000/cumm) Clinical features • abrupt or sudden onset • Petechiae over the skin, gum bleeding, epistaxis and mild fever which usually resolve spontaneously within 6 months. • Steroid therapy is indicated only if thrombocytopenia is severe. Chronic immune thrombocytopenic purpura • Persistent thrombocytopenia lasting more than 6 to 12 months. • Adults. • F:M ratio is 3:1 • Pathogenesis: autoimmune disorder formation of antiplatelet antibodies directed against membrane glycoproteins (IIb-IIIa or Ib-IX of platelets). IgG type. Laboratory Findings of ITP: Peripheral blood  Platelet count: Markedly reduced (below 80,000/cumm).  Hemoglobin: depending on the duration and amount of bleeding (7–12 g/dL).  Bleeding time: prolonged  PT, APTT: normal. Peripheral smear:  Platelets:Thrombocytopenia megathrombocytes/giant platelets,  RBCs: Chronic loss of blood may result in microcytic hypochromic anemia  WBCs: Usually within normal range. Bone marrow •Cellularity: Hypercellular. •Megakaryopoiesis: moderate immature and mature forms of megakaryocytes. •Erythropoiesis: normoblastic erythroid hyperplasia. constant bleeding cause iron deficiency resulting micronormoblastic erythroid hyperplasia. •Myelopoiesis: Normal. •Storage iron: depletion of iron stores in case of severe bleeding. Tourniquet test: Positive. Tests for platelet autoantibodies: May be positive. Evans syndrome : Term used for autoimmune hemolytic anemia (AIHA) along with immune thrombocytopenia • more common in women. • Antibodies against red cells and platelets. • Diagnosis of ITP : exclusion of causes of secondary thrombocytopenia,TTP. hypersplenism, MDS, acute leukemias, heparin induced thrombocytopenia and artifactual dumping of platelets due to EDTA, platelet agglutinins or due to platelet “satellitism' in which platelets are present on the surface of white blood cells. SECONDARY IMMUNE THROMBOCYTOPENIC PURPURA Broadly includes all forms of immune thrombocytopenias except primary ITP: 1.Associated with autoimmune diseases: SLE and rheumatoid arthritis 2.Drug-associated thrombocytopenia: quinine, digitoxin, quinidine, heparin, gold and sulfonamides. 3. Post-transfusion purpura (PTP): abrupt onset of thrombocytopenia and mucosal bleeding 1 week after the transfusion of PRC. 4.ITP in pregnancy (Gestational thrombocytopenia): No treatment is required if platelet count is >70,000/cumm 5. Neonatal thrombocytopenia: common causes are septicemia, hypoxia, respiratory distress syndromes, necrotizing entercolitis. 6. Hepatitis C-reIated thrombocytopenia: development of antiplatelet antibodies due to autoimmune mechanism.. 7.Heparin-induced thrombocytopenia (HIT): Type I: develops immediately following heparin therapy clinically insignificant with mild thrombocytopenia. resolves after heparin is discontinued probably due to direct plateletaggregation induced by heparin. Type II: severe thrombocytopenia develops 1 -2 weeks after starting heparin therapy life-threatening thrombosis in both veins and arteries, known as “white clot syndrome”. Pathogenesis of HIT SECONDARY THROMBOCYTOPENIA • Patient has a systemic disease with, one of the manifestations being thrombocytopenia. 1. Acquired pure amegakaryocytic thrombocytopenia: viral infections, septicemia, drugs and exposure to toxic chemicals. Bone marrow: lack of megakaryocytes; myelopoiesis and erythropoiesis are normal. 2. Liver disease: multifactorial; reduced production of TPO, antibodies against platelets, marrow suppression, splenic sequestration splenomegaly. 3.Dengue hemorrhagic fever (DHF): caused by flavi virus transmitted by Aedes aegypti (a freshwater mosquito). Dengue flavivirus targets endothelial cells, leukocytes, platelets and megakaryocytes. Thrombocytopenia (in the range of 5000-80,000/cumm) may occur. • 4. Thrombotic microangiopathy: spectrum of clinical syndromes characterized by widespread formation of platelet-fibrin thrombi in the microcirculation, mainly composed of platelet aggregates. Two closely related entities namely TTP and HUS are included under thrombotic microangiopathy Thrombotic Thrombocytopenic Purpura (TTP) and Hemolytic-Uremic Syndrome (HUS) • The classic five symptoms of TTP: 1.Microangiopathic hemolytic anemia (MAHA) 2.Thrombocytopenia 3.Transient neurologic symptoms 4.Fever 5.Renal failure. • HUS is distinguished from TTP by absence of fever and neurologic symptoms prominence of acute renal failure (uremia) primarily affects children different pathogenesis Pathogenesis of thrombotic thrombocytopenic purpura Pathogenesis of hemolytic-uremic syndrome • Laboratory diagnosis of thrombotic microangiopathies Peripheral blood Hemoglobin: Decreased (less than 6 g/dL). Platelet count: Markedly reduced often below 20,000/cu mm Peripheral smear RBCs: Show fragmented red cells (schistocytes), polychromatophils, nucleated RBCs and microspherocytes. WBCs: Show mild leukocytosis with a shift to left. Platelets: Markedly reduced. Reticulocyte count: Increased. Prothrombin time (PT) and activated partial thromboplastin time (APTT) :normal, because the coagulation system is not activated. Urine: moderate proteinuria and gross and microscopic hematuria. Morphology Blood vessels: Deposition of PAS-positive platelet-fibrin microthrombi in arterioles and capillaries throughout the body. mainly seen in the heart, brain and kidneys. QUALITATIVE PLATELET DISORDERS (PLATELET FUNCTION DISORDERS) • produce defects in the formation of hemostatic plug and thus result in bleeding. • characterized by prolonged bleeding time and normal platelet count. Hereditary Disorders of Platelet Function 1)Defective adhesion of platelets: A) Bernard-Soulier (giant platelet) syndrome: Autosomal recessive. Hereditary deficiency of the platelet membrane glycoprotein complex Ib-IX. ◆ Purpura, bruising, epistaxis and gingival bleeding during early life. Main lab findings PS: mild thrombocytopenia and giant platelets. Prolonged BT Deficient, aggregation with risotectin not corrected by addition of normal plasma B) von Willebrand’s disease : characterized by reduced synthesis of vWF platelet adhesion to subendothelial collagen is defective. Since it is a plasma protein disorder rather than a platelet functional disorder, it is discussed with coagulation disorders 2)Disorders of platelet secretion: Defect in the secretion due to lack of normal storage granules or due to defect in release of granules ( dense granules or alpha granules). Storage pool deficiency (SPD): autosomal dominant heterogeneous group of disorders deficiency of dense granules. Gray platelet syndrome: lack of α-granule proteins because of which the platelets and megakaryocytes appear gray (pale) on peripheral blood smear. • 3)Defective platelet aggregation Glanzmann thrombasthenia : Autosomal recessive disorder. Deficiency of glycoprotein IIb-IIIa (protein complex that helps in the formation of “bridges” between platelets by binding fibrinogen) Clinical presentation: manifests at birth with increased bleeding from the umbilical cord stump. Bleeding following circumcision. Life long muco-cutaneous bleeding tendency in the form of epistaxis, ecchymoses and bleeding from the gums. Lab findings of GT: Bleeding time:prolonged Platelet: count & morphology normal. Peripheral smear: platelets fail to aggregate; seen as round and discrete. PT & APTT: within normal range. Platelet aggregation to ADP, thrombin, collagen and epinephrine is deficient Aggregation to ristocetin: normal since it induces vWF binding to GP Ib/IXa pathway that is not impaired in Glanzman disease.  Impaired clot retraction. Flow cytometry: Deficiency of CD41/CD61 on platelet. Giant platelet disorders • Giant platelets are seen in a no. of congenital and acquired conditions • Inherited giant platelet disorders are a group of rare disorders characterized by thrombocytopenia, giant platelets and variable bleeding symptoms. ACQUIRED PLATELET FUNCTION DISORDERS 1.Drug Induced Platelet dysfunction: analgesics (aspirin, NSAIDs, acetaminophen), antibiotics (penicillins and cephalosporins), psychotropic drugs and, garlic, red pepper and fish oil also impair platelet function. 2. Paraproteinemias: more common in patients with IgA myeloma and macroglobulinemia than with other types of myeloma and MGUS. Immunoglobulins bind to the platelet surface non-specifically and impair adhesion and aggregation of platelets. 3. Myeloproliferative neoplasms & Myelodysplastic syndromes: acquired storage pool disease and von Wilbrand disease like platelet defect DISORDERS OF COAGULATION • Screening coagulograms are the baseline tests used to assess the hemostasis. These tests are used when the patient presents with a bleeding diathesis pre-operativeiy to exclude the likelihood of bleeding during surgery/post operative period The three main tests carried out are: Platelet count Prothrombin time (PT) Activated partial thromboplastin time (aPTT) Prothrombin time: Principle: measures the clotting time of recalcified plasma in the presence of an optimal concentration of tissue extract (thromboplastin) indicates efficiency of extrinsic clotting system. Also depends on factors V, VII and X and fibrinogen concentration of the plasma. Normal values : With rabbit thromboplastins : 11 and 16 sec recombinant human thromboplastin it is shorter (10–12sec) Common causes of a prolonged PT 1) Administration of oral anticoagulant drugs (vitamin K antagonists) 2) Vitamin K deficiency 3) presence of a direct acting inhibitor of factor Xa 4) Liver disease, particularly obstructive jaundice 5) Vitamin K deficiency 6) Disseminated intravascular coagulation. Activated partial thromboplastin time • Principle: measures the clotting time of plasma after the activation of contact factors and the addition of phospholipid and CaCl2 but without added tissue thromboplastin indicates the overall efficiency of the intrinsic pathway Normal range: 26-40s • The common causes of a prolonged APTT are as follows: 1. Disseminated intravascular coagulation 2. Liver disease 3. Massive transfusion with plasma-depleted red blood cells 4. Administration of or contamination with heparin or other anticoagulants 5. Nonspecific circulating anticoagulant (such as an LAC) 6. Presence of a direct acting anticoagulant drug (e.g. anti-IIa or anti-Xa agents) 7. Deficiency of coagulation factor other than factor VII Thrombin time • Principle: Thrombin is added to plasma and the clotting time is measured. TT is affected by the concentration and function of fibrinogen and by the presence of inhibitory substances. Normal range: should be within 2s of the control (i.e. 15 to 19s). • Common causes of prolonged TT are as follows: 1.Hypofibrinogenaemia 2.Dysfibrinogenaemia 3. Oral or parenteral direct thrombin inhibitors 4. Raised concentrations of fibrin degradation products (FDP) 5. Hypoalbuminaemia 6. Paraproteinaemia. • TESTS FOR FIBRINOLYTIC ACTIVITY Whole blood clot lysis: Normal blood clots do not dissolve in 24 hours. When there is increased fibrinolytic activity, the clot undergoes lysis within 30 to 60 minutes after clotting. Euglobulin lysis time: Quantitative measure of fibrinolytic activity. Euglobulin fraction of plasma includes plasminogen, plasminogen activators and fibrinogen. Lysis normally occurs in 2 to 4 hours. Values less than 2 hours indicate increased fibrinolysis. Fibrin degradation products: Serum/plasma of the patient is collected and latex particles coated with specific antibodies to purified fibrin degradation products (FDP) are added. Presence of agglutination suggests the presence of FDP in the serum. Use: Aids in diagnosis of DIC. D-dimer: D-dimer is a specific marker of DIC Coagulation disorders: Classification HEMOPHILIA A— FACTOR VIII DEFICIENCY sex linked recessive disease gene maps to Xq 28 As males have only one X-chromosome, synthesis of FVIII is deficient as the Xh gene is defective. Males are the sufferers and females are the carriers  rare female homozygous cases are encountered HEMOPHILIA A— FACTOR VIII DEFICIENCY • Factor VIII has 2 components: VIII C and vWF Factor VIII level and clinical severity in hemophilia A Laboratory Findings Bleeding time: Normal. Clotting time: Prolonged. Platelet count: Normal. Prothrombin time: Normal. Activated partial thromboplastin time (APTT): Increased (normal 30–40 seconds. Factor VIII :assessed by assays with mixtures of patient plasma and factor VIII-deficient plasma. Carrier detection: DNA markers Complications of Hemophilia • Deforming arthritis and contractures: • Anemia Causes of Death  Intracranial hemorrhage  Prolonged bleeding Treatment:  Factor VIII concentrates  Recombinant factor VIII  Gene therapy is also under trial Von Willebrand Disease • Bleeding disorder characterized by a platelet function defect and a coagulation defect • Group of multiple disorders with variable clinical picture and modes of inheritance. • A large number of variants of the disease have been identified like type 1, 2A, 2B, 2N, 2M, 3 • Quantitative deficiency of vWF: Type 1 and type 3 :decreased quantity of circulating vWF. Type 1: autosomal dominant ;relatively mild disorder ;about 75% of all cases. Type 3: autosomal recessive; least common type and severe disorder associated with extremely low levels of vWF. • Qualitative defects in vWF: Type 2 accounts for 25% of all cases autosomal dominant. Type 2a: most common of type 2; vWF is expressed in normal amounts, but has defective assembly of multimers. Type 2b: synthesis of an abnormal vWF with increased affinity for platelets which results in thrombocytopenia Clinical Features  Bleeding manifestations: mild and remain undetected.  Common symptoms: spontaneous bleeding from mucous membranes (e.g. epistaxis)  Excessive bleeding from wounds or menorrhagia.  Severe cases: manifestations may be similar to hemophilia A Laboratory findings in von Willebrand disease • • • • • • • • • • • Tourniquet test (Hess test): positive (defective platelet adhesion). Bleeding time: Prolonged (platelet function defect). APTT: Prolonged (secondarily reduced VIII c activity) vWF assay: levels Ristocetin induced aggregation: defective and is diagnostic of vWD. vWF immunoassay: assayed by ELISA or automated assays (reduced in type I vWD while in type 2 vWD, the vWF : Ag levels may be normal indicating that just measuring vWF : Ag is not enough for diagnosing vWD). Multimeric analysis of vWF Genetic studies of specific CDNA regions. Rapid type 2 multifunction vWF assay vWF: 2b3a assay vWF: GPIbM assay - a newer useful technique Hemophilia B (Christmas Disease, Factor IX Deficiency) X-linked recessive trait Presents with variable clinical severity.  Assay of factor IX should be done to diagnose Christmas disease (named after the first patient). Clinical Features usually milder than those of hemophilia A. In both the diseases, hemarthrosis is the common presentation.  Treatment is by infusion of purified or recombinant factor IX. Lab Findings of Hemophilia B Laboratory Findings Similar to hemophilia A Bleeding time: Normal. Clotting time: Prolonged. Platelet count: Normal. Prothrombin time: Normal. Activated partial thromboplastin time (APTT): Increased (normal 30– 40 seconds). Factor IX assay: Factor IX is decreased Summary of laboratory test in hereditary coagulation disorders RARE HEREDITARY BLEEDING DISORDERS 1. HYPOFIBRINOGENEMIA AND AFIBRINOGENEMIA: Fibrinogen is synthesized in liver with three separate genes on chromosome 4. Defect in synthesis, secretion or intracellular processing of final gene product. Inheritance : Autosomal recessive. Hemorrhages not as severe as in hemophilia All tests in which appearance of fibrin clot is the endpoint, like PT, APTT, TT are prolonged and get corrected with addition of normal plasma. 2.DYSFIRRINOGENEMIA: Autosomal dominant Bleeding mild (easy bruising, menorrhagia and soft-tissue bleeding). Acquired dysfibrinogenemia: severe liver disease, hepatomas, renal cell carcinoma & autoimmune disorders. Thrombin time (TT) : prolonged in majority of the cases PT is more sensitive than APTT in diagnosing these cases. Reptilase time is more prolonged than TT Euglobuiin clot lysis time (measure of fibrinolytic potential) is helpful in detecting abnormal fibrinogen. 3.FACTOR XIII DEFICIENCY: Autosomal recessive Patients with plasma levels of < 1% of normal F XIII level manifest abnormal bleeding from umbilical cord stump at birth. Diagnosis: by screening test clot stability test using the 5M urea solubility. PT and APTT are normal in these cases. 4. FACTOR V DEFICIENCY (PARAHEMOPHILIA): Autosomal recessive epistaxis, easy bruising, menorrhagia and excessive bleeding following dental extractions. Both PT and APTT: prolonged TT : within normal range. Acquired F V deficiency: Liver disease , disseminated intravascular coagulation (DIC) Acquired coagulation disorders DISSEMINATED INTRAVASCULAR COAGULATION • Syndrome in which either the extrinsic or intrinsic or both pathways are activated to produce multiple fibrin clots in small blood vessels. • Acquired pathological state due to presence of more than physiological amount of thrombin in systemic circulation Major Disorders Associated with DIC 1. Obstetric complications Amniotic fluid embolism Eclampsia Premature separation of placenta Retained dead fetus/placenta HELLP syndrome Dead fetus syndrome 2.Malignancies AML-M3 (Acute Promyelocytic leukemia) Metastatic mucus secretang adenocarcinoma Lymphoproliferative disorders 3. Infections Meningococcal septicemia Septic abortion Clostridium welchii septicemia Gram -ve sepsis (E. coli and Pseudomonas) 4. Miscellaneous Snake bite Heat stroke Post surgery/massive trauma Eat embolism Severe pancreatitis Giant hemangiomas Severe burns Anaphylaxis PNH Hepatic failure Head injury Clinical manifestations of DIC • Abrupt onset of bleeding in the form of ecchymoses, petechiae and from sites of venipuncture. • Gum bleeding, epistaxis and gastrointestinal hemorrhage may occur. • Severe bleeding, state of shock may develop, Acute renal failure • Clinical features of the underlying disease are present. Laboratory Findings in DIC Screening assays:  Platelet count: Decreased due to utilization of platelets in microthrombi.  Prothrombin time: Increased.  APTT: Increased as a result of consumption and inhibition of the function of clotting factors.  Thrombin time (TT): Increased because of decreased fibrinogen  Fibrinogen: Decreased.  Peripheral smear: Microangiopathic hemolytic anemia. Confirmatory tests:  FDP (fibrin degradation/split products): Secondary fibrinolysis results in generation of FDPs, which can be measured by latex agglutination.  D-dimer test: It is specific for diagnosing DIC. Effects and signs of DIC Vitamin K Deficiency Fat-soluble vitamin and requires bile for its absorption. Required by liver for the production of factors II, VII, IX, X, protein C and protein S. Deficiency results in release of the above coagulation factors in incomplete and inactive form from the liver. Vitamin K deficiency may develop when absorption is defective as in obstructive jaundice, pancreatic disease or small bowel disease. Bleeding manifestations show dramatic response to parenteral vitamin K therapy. Oral anticoagulant drug warfarin: vitamin K antagonist THROMBOPHILIA • Thrombophilia refers to hereditary and acquired conditions associated with a tendency for arterial and venous thrombosis. • 5 major ones in order of frequency in general population are: 1) Factor V Leiden 2) Prothrombin 20210A mutation. 3) Protein S deficiency 4) Protein C deficiency 5) Anti thrombin deficiency Major causes of hypercoagulable state INHERITED HYPERCOAGULABLE STATES A)Deficiency of Antithrombotic Factors: 1.ANTITHROMBIN III DEFICIENCY: Antithrombin III is a physiological inhibitor of thrombin in circulation Deficiency results in thrombus formation. Autosomal dominant can be quantitative or qualitative. Assessed by coagulation/chromogenic/ ELISA/or immuno-assays. 2.Protein C Deficiency: • Proteins C and S act as a complex which degrades factors Va and VIIIa. • When they are deficient, activated factor V and VIII are not neutralized and resulting activation of the clotting system, which promotes thrombosis. 3.Protein S Deficiency: presentation is similar to protein C deficiency. B)Increased Prothrombotic Factors 1.Activated Protein C (APC) Resistance (Factor V Leiden): Most common genetic disorder associated with familial thrombophilia. • A point mutation (results in a glutamine to arginine substitution at position 506) in the factor V gene (this variant is known as factor V Leiden/Leiden mutation) • It may be heterozygous or homozygous. ACQUIRED HYPERCOAGULABLE STATES ACQUIRED HYPERCOAGULABLE STATES • 1.Antiphospholipid Antibody Syndrome (APLA/APS) : • Presence of a family of antibodies in the patient’s plasma known as antiphospholipid antibodies. Two important antibodies:  lupus anticoagulant antibody  anti-β2 glycoprotein antibody. Lupus anticoagulant • Type of antiphospholipid antibody which results in prolongation of coagulation pathway in which phospholipid is used e.g.. APTT. • detected using coagulation assay and immunoassays. Types Antiphospholipid antibody syndrome •Primary antiphospholipid syndrome: do not have any predisposing cause and their only manifestation is hypercoagulable state. •Secondary antiphospholipid syndrome: association with autoimmune diseases like SLE. Clinical Features: 1. Hypercoagulable state 2. Repeated spontaneous abortions 3. Thrombocytopenia. Laboratory Tests: • APTT: Prolonged. • Factor VIII levels: Normal. • Prothrombin time: Normal. • Thrombin time: Normal. • Fibrinogen level: Normal. Dilute Russell’s viper venom test (DRVVT) : Russell’s viper venom (RVV) activates factor X leading to fibrin clot. Lupus anticoagulant prolongs clotting time by binding to RVV and preventing the action of RVV. Confirmatory test : Antiphospholipid antibodies are detected by ELISA and radioimmune assay (RIA). Homocysteinemia • An increased plasma concentration of homocysteine is known as homocysteinemia, which predisposes to atherosclerosis and thrombosis. • plasma homocysteine genetically determined • Also partly controlled by the dietary content of vitamin B12, folate and pyridoxine. • Mechanism of thrombosis is not clearly known. It may be due to: – Endothelial damage induced by homocysteine. – Linkage between homocysteine metabolites and various proteins, including fibrinogen. Approach to investigation of a bleeding disorder Approach to bleeding disorder with normal prothrombin time (PT) and activated partial thromboplastin time (APTT) Approach to bleeding disorder with prolonged activated partial thromboplastin time (APTT) and normal prothrombin time (PT) Approach to bleeding disorder with prolonged activated partial thromboplastin time (APTT) and prolonged prothrombin time (PT) Approach to bleeding disorder with normal activated partial thromboplastin time (APTT) and prolonged prothrombin time (PT)