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البقرة البقرة سورة ((3232 ) ) سورة

diagnostic diagnostic approach to a approach to a bleeding childbleeding child

Made byMade byAhmad Abdel-Fadeel Ahmad Abdel-Fadeel

HoussinHoussin

OBJECTIVESOBJECTIVES

- Overview of hemostasis .Overview of hemostasis .

- Clinical approach in making a Clinical approach in making a diagnosis .diagnosis .

- Review the most common bleeding Review the most common bleeding conditions and the current treatment conditions and the current treatment strategies .strategies .

Overview of hemostasisOverview of hemostasis

There are four distinct phases in hemostasis which is geared to stop blood loss.

•First the damaged blood vessel narrows (vasoconstriction) to reduce the blood flow and therefore blood loss. This happens almost immediately once the blood vessel is damaged.

•Second the platelets in the blood (small particles of larger cells) adheres to the lining of the damaged blood  vessel and stick to each other to plug the site of blood loss (platelet plug).  This is known as the platelet phase and occurs within seconds of a tear in the blood vessel.

• The third is the clotting phase or coagulation phase in which the various clotting factors activate each other (coagulation cascade) to turn the liquid blood components into a more semi-solid to solid mass (blood clot). The clot also retracts to draw the damaged ends of the blood vessel together and form a tight seal and this is sometimes mentioned as separate phase known as clot retraction.

•The last phase involves the removal of the clot once the blood vessel is completely repaired. The clot may be dissolved (fibrinolysis) or sometimes contributes to scar formation at the site (fibrosis).

Monagle P, Barnes C, Ignjatovic V, et al. . 2006

Overview of HaemostasisOverview of Haemostasis

INJURY

Collagen Exposure

Platelet Adhesion and release reaction

Platelet aggregation

VASOCONSTRICTION

Serotonin Platelet Phospolipid

Thromboxane A2 ADP

Primary haemostatic plug

Stable haemostatic plug

Tissue Factor

Coagulation

Thrombin

Fibrin

Fibrinolysis

Kinins HMW Kininogen

Kallikrein Contact Activation

XII Prekallikrein

XIIa

XIa XI

IXa Ca++ IX

VIIIa VIII

Ca++

Phospholipid

Intrinsic Pathway

Xa X

Va V

Ca++

Phospholipid XIII

II IIa

XIIa

Fibrinogen Fibrin XIII

Common Pathway

VII VIIa

Ca++

Tissue Factor

Coagulation cascadeCoagulation cascade

Extrinsic Pathway

Clinical approach in making a diagnosisClinical approach in making a diagnosis

1-HISTORY

Clinical evaluation of a bleeding patient begins with taking a careful history, taking into account the child's age, sex, clinical presentation, past history, and family history.

the history also should include complete details as to the type of bleeding, location, degree of symptoms, nature of provoking injuries, and whether such injuries are consistent with the child’s development and level of activity

( Khair and Liesner.,2006 ) ( Khair and Liesner.,2006 )

Age and sex of the patient 

• An inherited bleeding disorder should be strongly considered when the onset of bleeding manifestations occurs in infancy or early childhood and is associated with a positive family history.•However, a negative family history does not exclude an inherited coagulation disorder, as up to one-third of patients with hemophilia have a negative family history .

Family history 

 The family history is helpful in formulating a possible diagnosis of an inherited disorder of coagulation.The presence of bleeding manifestations only in male siblings and maternal uncles is suggestive of X-linked recessive inheritance, such as that seen in hemophilia A or B.

In contrast, in autosomal dominant traits such as hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease), an accurate pedigree will show affected individuals of both sexes for several generations.

In autosomal recessive disorders, such as severe forms of the rarer coagulation factor deficiencies (eg, factor VII or factor XI deficiency), the family history may be negative; consanguinity increases the probability of such disorders.

Medication  

• specific information should be sought about the ingestion of aspirin, aspirin-containing over-the-counter medications, and other non-steroidal anti-inflammatory drugs such as ibuprofen or naproxen. Such drugs impair platelet function and may exacerbate an underlying coagulation disorder .

•In addition, use of such drugs within one to two weeks of platelet function testing may cause abnormalities, which may lead to further expensive and unnecessary studies.

Is a bleeding tendency present or not ?

While assessing a patient, one has to keep in mind that not all bleeding episodes suggest a generalized bleeding disorder.

For example, epistaxis may be caused by rhinitis, trauma, superficial vessels, or dry air,

and abnormal post-surgical bleeding (eg, tonsillectomy) may be caused by surgical trauma rather than a generalized bleeding disorder.

2- 2- ExaminationExamination General stability, vitals signs, evidence of chronic

disease, evidence of malignancy. Skin stigmata : > PETICHEAE > ECHYMOSES >JOINT BLEED &DEEPSEATED HEMATOMAS > HEPATOSPLENOMEGALY > SIGNIFICANT LYMPHADENOPATHY > ACTIVE AND PLAYFUL VS. ILL LOOKING > DYSMORPHIC FEATURES > CAFÉ-AU-LAIT SPOTS >TELANGIECATIC VESSELS >HEMANGIOMAS

3- laboratory evaluation3- laboratory evaluation

•certain laboratory tests of certain laboratory tests of hemostasis are used as initial hemostasis are used as initial screening tests, whereas screening tests, whereas other more specific tests are other more specific tests are performed at a later time in performed at a later time in order to narrow the order to narrow the possibilities or make a possibilities or make a definitive diagnosis.definitive diagnosis.

•The usual initial screening tests include

- Quantitation of platelets

- examination of the peripheral blood smear

- prothrombin time/international normalized ratio (PT/INR)

- activated partial thromboplastin time (aPTT)

- the fibrinogen activity level.

•Proper collection of the blood sample is essential for interpreting the results of clotting tests.

•Blood for coagulation tests should not be drawn from an existing heparinized indwelling line.

•Coagulation tests are performed on blood anticoagulated with a solution of sodium citrate in a ratio of nine parts of blood to one part of citrate.

4- DIAGNOSTIC APPROACH 4- DIAGNOSTIC APPROACH 

A-ABNORMAL INITIAL A-ABNORMAL INITIAL COAGULATION TESTSCOAGULATION TESTS

1- Normal PT and prolonged aPTT1- Normal PT and prolonged aPTT  

  An isolated prolongation of aPTT is An isolated prolongation of aPTT is characteristic of intrinsic pathway characteristic of intrinsic pathway coagulation factor .coagulation factor .

The following conditions are characterized The following conditions are characterized by prolonged aPTT:by prolonged aPTT:

●●Hemophilia – Hemophilia A (factor Hemophilia – Hemophilia A (factor VIII deficiency) is the most common VIII deficiency) is the most common inherited disorder yielding a inherited disorder yielding a significantly prolonged aPTT.significantly prolonged aPTT.

●●Factor XI deficiency – Factor XI Factor XI deficiency – Factor XI deficiency is seen more commonly deficiency is seen more commonly in Ashkenazi Jews and presents with in Ashkenazi Jews and presents with a variable history of bleedinga variable history of bleeding

●Lupus anticoagulants – Lupus anticoagulants are acquired inhibitors that may produce a prolonged aPTT. They are commonly seen in children, frequently associated with recent infections, particularly viral infections, and usually are transient.

●Deficiencies of factor XII, high molecular weight kininogen (HMWK), and prekallikrein usually are asymptomatic and not associated with clinical bleeding.

●Heparin contamination – and is likely if the thrombin time (TT) is prolonged

2- Prolonged PT and normal aPTT 

  - An isolated prolongation of the PT is

characteristic of inherited or acquired factor VII deficiency.

- Inherited factor VII deficiency displays phenotypic and molecular heterogeneity, whereas acquired factor VII inhibitors are very rare occurrences during childhood.

3- Prolonged PT and aPTT

A- Well childA- Well child

Prolongation of both PT and aPTT in a bleeding child who is otherwise well indicates an inherited disorder within the common pathway (factor X, V, II (prothrombin) or fibrinogen; these deficiencies are rare) or an acquired disorder involving multiple pathways

B- Sick childSick child

In a sick child with prolongation of both In a sick child with prolongation of both PT and aPTT, disorders to consider are PT and aPTT, disorders to consider are disseminated intravascular coagulation disseminated intravascular coagulation (DIC), fulminant sepsis with DIC, severe (DIC), fulminant sepsis with DIC, severe hepatocellular dysfunction, and severe hepatocellular dysfunction, and severe vitamin K deficiency. Major vessel vitamin K deficiency. Major vessel thrombosis, consumption coagulopathy thrombosis, consumption coagulopathy in certain vascular lesions, and acute in certain vascular lesions, and acute respiratory distress syndrome (ARDS) respiratory distress syndrome (ARDS) are other rare causes are other rare causes

B- NORMAL INITIAL COAGULATION B- NORMAL INITIAL COAGULATION TESTSTESTS

Normal platelet countNormal platelet count  In children with bleeding symptoms and an initial

laboratory screen with a normal platelet count and initial coagulation screening tests, possible diagnoses include

1- von Willebrand disease (vWD)1- von Willebrand disease (vWD)

2- some cases of hemophilia2- some cases of hemophilia

3- factor XIII deficiency3- factor XIII deficiency

4- vascular abnormality4- vascular abnormality

5- a fibrinolytic disorder.5- a fibrinolytic disorder.

6- platelet function disorder 6- platelet function disorder

Classic inherited disorders of platelet function are relatively rare and include:

●Glanzmann thrombasthenia, which is characterized by a defect in the platelet glycoprotein IIb/IIIa complex

●Bernard-Soulier syndrome, which is characterized by a defect in one of the components of the platelet glycoprotein Ib-IX-V complex, giant platelets.

●Storage pool diseases, including Chediak-Higashi syndrome, Hermansky-Pudlak syndrome, Wiscott-Aldrich syndrome, and thrombocytopenia with absent radius syndrome.Park CH, Seo JY, Kim HJ, et al . 2010

- Review the most common Review the most common bleeding conditionsbleeding conditions

And The current treatment And The current treatment strategiesstrategies

1- Hemophilia

Hemophilia is a blood clotting disease that arises due to the deficiency of one of the clotting factors.- It is the most common of the bleeding/clotting disorders.- About 85% of hemophilics have a deficiency of Factor VIII,while the other 15% have a deficiency of Factor IX.A very rare type of hemophilia involves Factor XI

- Types of Hemophilia

Hemophilia A

In this type of hemophilia, there is a deficiency in Factor VIII. This clotting factor is manufactured in the liver and the endothelial cells lining the blood vessel, circulates in the blood by binding to von Willebrand factor (vWF) and is activated by thrombin. Once activated Factor VIIIa then works with Factor IX, calcium and phospholipids to activate Factor X.

Hemophilia B

This type of hemophilia is due to a deficiency in Factor IX. It is also known as Christmas Disease. Factor IX circulates in the blood stream in an inactive form and depends on Factor XI to activate it (IXa). Once activated it works with Factor VIII, calcium and phospholipids to activate Factor X.

Hemophilia C

A third type of hemophilia known as hemophilia C is a mild form of hemophilia. It is not as common as other blood clotting disorders and is mainly seen in certain ethnic groups. This type of hemophilia is due to a deficiency of Factor XI and prevents the activation of sufficient quantities of Factor IX

females can have hemophilia :females can have hemophilia :

•Lyonization of the normal X chromosome

•Turner syndrome ( XO)

•Father with hemophilia/ mom as a carrier

•vW type 2 N ( Normandy)

HEMOPHILIA SEVERITY LEVELSHEMOPHILIA SEVERITY LEVELS

•Severe <1% activity level - Spontaneous bleeds

•Moderate 1 to 5% activity --Trauma/surgery bleeds ,Occasional joint bleeds

•Mild 5 to 30% activity - Major trauma/surgery , Rare joint bleeds

Treatment of hemophilia :Treatment of hemophilia :1 u/kg raises FVIII levels 2% , 1/2 life : 12 hrs1 u/kg raises FVIII levels 2% , 1/2 life : 12 hrs

1 u/kg raises FIX levels 1 % , 1/2 life 20-24 1 u/kg raises FIX levels 1 % , 1/2 life 20-24 hrshrs

Minor Bleeding Episodes :-Minor Bleeding Episodes :-•Early joint bleeds

•Soft tissue & muscle bleeds

•Nose & gum bleeding not responding to local measures- 40 - 50% correction– FVIII : 25 units / kg– FIX : 50 units / kg

Major Bleeding Episodes :-Major Bleeding Episodes :-•Advanced soft tissue & muscle

bleeds

•Head & neck injuries

•Gastrointestinal bleeding

•Advanced joint bleeding•80 – 100 % correction•FVIII : 50 units / kg•FIX : 100 units / kg

Plummer ES and Crary SE . 2013 . 2013

Current ProductsCurrent Products• Plasma Products: plasma-derived factor VIII Plasma Products: plasma-derived factor VIII

concentrateconcentrate

• Porcine Factor: Porcine Factor: – Use was halted due to parvovirus/retrovirus Use was halted due to parvovirus/retrovirus

sequences discoveredsequences discovered

• Recombinant products: Recombinant products: – First Generation: Recombinate, Kogenate, First Generation: Recombinate, Kogenate,

HelixateHelixate– Second Generation: Kogenate FS, Helixate FSSecond Generation: Kogenate FS, Helixate FS– Third Generation: AdvateThird Generation: Advate

• DDAVP: DDAVP: – Causes release of factor VIII/vWFCauses release of factor VIII/vWF– Increased factor activity in 30-60”Increased factor activity in 30-60”– For mild hemophiliacs and mild bleeding For mild hemophiliacs and mild bleeding

symptoms symptoms

Hemophilia Treatment Center Hemophilia Treatment Center Team MembersTeam Members

•Patient / FamilyPatient / Family

•HematologistHematologist

•NurseNurse

•Social WorkerSocial Worker

•Physical Physical

TherapistTherapist

•OrthopedistOrthopedist

•Primary CarePrimary Care

• Infectious Infectious

DiseaseDisease

•GeneticsGenetics

•PharmacyPharmacy

•DentalDental

•HepatologistHepatologist

1- von Willebrand disease (vWD)1- von Willebrand disease (vWD)

- A mild bleeding disorder caused by a deficiency or malfunctioning of von Willebrand factor (vWF).

- It is a fairly common inherited bleeding disorder that affects both males and females.

- It may be autosomal dominant (types 1, 2A, 2B, 2M), autosomal recessive (type 2N) or compound heterozygosity (type 3).

• von Willebrand factor Binds to platelet receptor GP Ib and to subendothelial structures such as collagen serving as bridge between platelets and subendothelium in damaged vessels

•Acts as bridge between adjacent platelets in vessels with high shear (arterioles) forming small platelet aggregates

•Binds to circulating factor VIII protecting it and prolonging FVIII t1/2 in the circulation from 2 to 8-12 hours.

- Types of von Willebrand DiseaseType 1 is the most common and in there is a partial

quantitative deficiency in von Willebrand factor (vWF)Type 2 the quantity of vWF may be normal but the factor

may be defective.

• Type 2A is the most common subtype with mutations in platelet binding.

• Type 2B is where there is a mutation of the platelet glycoprotein 1b (Gp1b) binding site.

• Type 2N is where there is a mutation in the factor VIII binding site.

• Type 2M is where there is abnormalities in platelet binding.

Type 3 is a severe deficiency (quantitative) in von Willebrand factor. It leads to a severe bleeding disorder but is rarely seen.

Acquired von Willebrand disease or Acquired von Willebrand disease or von Willebrand syndrome is due to von Willebrand syndrome is due to one of the following :one of the following :

•antibody against vWF

•degradation of vWF

•absorption of vWF by malignant cells or activated platelet

This is seen with Wilm’s tumor, multiple myeloma, systemic lupus erythematosus (SLE) and leukemia .

- Treatment of von Willebrand Treatment of von Willebrand Disease :Disease :

Treatment is not necessary in most cases since the disease is so mild. Although there is prolonged bleeding, clotting and subsequently cessation of bleeding will eventually occur.

•Desmopressin (DDAVP)  is usually administered via a nasal spray.

•Parenteral administration (injections) may only be necessary in severe cases but has limited benefit in type 3 vWD.

• Infusions of factor VIII or von Willebrand factor (vWF) may be considered in patients who do not respond to DDAVP or type 3 vWD.

•Anti-fibrinolytic agents delays the breakdown of blood clots.

Treatment Guidelines in Treatment Guidelines in VWDVWD TYPETYPE

11

2A2A

2B2B

2M2M

2N2N

33

TREATMENTTREATMENT

DDAVPDDAVP

DDAVP/FVIII-VWFDDAVP/FVIII-VWF

FVIII-VWFFVIII-VWF

FVIII-VWFFVIII-VWF

FVIII-VWFFVIII-VWF

FVIII-VWFFVIII-VWF

Nichols WL, Hultin MB, James AH, et al. 2008

3- thrombocytopenia3- thrombocytopenia

Thrombocytopenia purpura (TP) Thrombocytopenia purpura (TP) is a is a bleeding disorder characterized bleeding disorder characterized by a very low number of platelets by a very low number of platelets (thrombocytes) circulating in the (thrombocytes) circulating in the blood stream.blood stream.

Causes and Types of Thrombocytopenia :

1- Idiopathic Thrombocytopenia Purpura (ITP) - This type of thrombocytopenia occurs for no known

reason. Antibodies formed by the body against the platelets (auto-antibodies) attach to the platelet membranes.

- This “marks” the platelets for destruction by the body’s immune system particularly within the spleen.

- In idiopathic thrombocytopenia purpura (ITP) the body still produces a normal level of platelets but these are rapidly removed from the circulation thereby leading to a platelet deficiency.

- This type of thrombocytopenia is seen with immune dysfunction often associated with diseases like HIV infection and autoimmune disorders.

- It may also occur in pregnancy and with the use of certain drugs like heparin. Provan D and Stasi R . 2010

2- Heparin-induced thrombocytopenia2- Heparin-induced thrombocytopenia ( (HITHIT))- may arise after the administration of

unfractionated heparin.

- This drug is an anticoagulant and when derived from natural sources (unfractionated) compared to synthetic formulas of lower molecular weight, the effects can sometimes be unpredictable.

- Antibodies are then formed against the heparin and certain platelet proteins which then attach to and activate the platelets.

- These platelets are then removed from the circulation thereby leading to a deficiency of platelets.

3- Thrombotic Thrombocytopenia Purpura (TTP)

In this type of thrombocytopenia, there is sudden formation of blood clots throughout the body even though there is no hemorrhage (bleeding) requiring clot formation.

In the process, the circulating platelet levels drop because the body uses the platelets to form these clots.

4- Hemolytic-Uremic Syndrome (HUS)4- Hemolytic-Uremic Syndrome (HUS)

Toxins produced in the gut by bacteria like E.coli are absorbed into the bloodstream where it triggers the rapid destruction of red blood cells and platelets. The patient usually has gastroentritis associated with E.coli infection and this conditions may also occur with other infections like Shigellosis

Other Causes of Low Platelet CountOther Causes of Low Platelet Count• Alcohol abuseAlcohol abuse

• LeukemiaLeukemia

• LymphomaLymphoma

• Aplastic anemia and other types of anemiaAplastic anemia and other types of anemia

4- vitamin K deficiency causes a mild bleeding disorder due to a deficiency of

clotting factors VII, IX, X and prothrombin (factor II). The liver utilizes vitamin K to synthesize these clotting factors.

5- Factor I deficiencyis due to a lack (afibrinogenemia), deficiency

(hypofibrinogenemia) or defective functioning (dysfibrinogenemia) of fibrinogen.

6- Blood vessel wall abnormalitieswhere there is a weakening of the wall which will easily

tear or rupture. These conditions are rare and includes :

• Hereditary hemorrhagic telangiectasia

• Ehlers-Danlos disease

• ScurvyLusher J, Pipe SW, Alexander S 2010

• SUMMARY AND RECOMMENDATIONSSUMMARY AND RECOMMENDATIONS

• The evaluation of a bleeding child begins with a careful The evaluation of a bleeding child begins with a careful history, taking into account the child's age, sex, clinical history, taking into account the child's age, sex, clinical presentation, past history, and family history. Bleeding presentation, past history, and family history. Bleeding into the skin and mucous membranes is characteristic of into the skin and mucous membranes is characteristic of platelet and blood vessel disorders, while coagulation platelet and blood vessel disorders, while coagulation disorders are characterized by musculoskeletal (ie, disorders are characterized by musculoskeletal (ie, muscle and joint) and soft tissue bleeding . The nature muscle and joint) and soft tissue bleeding . The nature and extent of the injuries producing bleeding symptoms and extent of the injuries producing bleeding symptoms should be noted. should be noted.

• A reasonable initial screening evaluation consists of A reasonable initial screening evaluation consists of quantitation of platelets, examination of the peripheral quantitation of platelets, examination of the peripheral blood smear, prothrombin time (PT), and activated blood smear, prothrombin time (PT), and activated partial thromboplastin time (aPTT); at our center we also partial thromboplastin time (aPTT); at our center we also measure a fibrinogen level. Normal values may vary with measure a fibrinogen level. Normal values may vary with age and among different laboratories . The results of the age and among different laboratories . The results of the initial testing help differentiate among the different initial testing help differentiate among the different diagnostic possibilities in the child with bleeding diagnostic possibilities in the child with bleeding symptoms . symptoms .

• Further testing of specific coagulation factors Further testing of specific coagulation factors depends upon the history and initial laboratory depends upon the history and initial laboratory testing. These tests often are performed in order testing. These tests often are performed in order to confirm a specific diagnosis of an inherited or to confirm a specific diagnosis of an inherited or acquired factor deficiency. acquired factor deficiency.

• If the above screening evaluation is normal and If the above screening evaluation is normal and suspicion remains high for a bleeding disorder, suspicion remains high for a bleeding disorder, diagnostic possibilities include von Willebrand diagnostic possibilities include von Willebrand disease, some forms of mild hemophilia, platelet disease, some forms of mild hemophilia, platelet function disorders and fibrinolytic disorders function disorders and fibrinolytic disorders (including factor XIII deficiency), and additional (including factor XIII deficiency), and additional testing (or consultation with a hematologist) testing (or consultation with a hematologist) should be pursued. Vascular abnormalities (eg, should be pursued. Vascular abnormalities (eg, Ehlers-Danlos syndrome or hereditary Ehlers-Danlos syndrome or hereditary hemorrhagic telangiectasia) and physical abuse hemorrhagic telangiectasia) and physical abuse should also be considered. should also be considered.

• REFERENCESREFERENCES

• Khair K, Liesner R. Bruising and bleeding in infants and children--a practical approach. Br J Haematol 2006; 133:221.

• Hoyer LW. Hemophilia A. N Engl J Med 1994; 330:38.

• Hsieh L, Nugent D. Factor XIII deficiency. Haemophilia 2008; 14:1190.

• Plummer ES, Crary SE, Buchanan GR. Prominent forehead hematomas ("goose-eggs") as an initial manifestation of hemophilia. J Pediatr 2013; 163:1781.

• Sadowitz D, Souid AK, Terndrup TE. Idiopathic thrombocytopenic purpura in children: recognition and management. Pediatr Emerg Care 1996; 12:222.

• Neunert C, Lim W, Crowther M, et al. The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. Blood 2011; 117:4190.

• Vesely S, Buchanan GR, Cohen A, et al. Self-reported diagnostic and management strategies in childhood idiopathic thrombocytopenic purpura: results of a survey of practicing pediatric hematology/oncology specialists. J Pediatr Hematol Oncol 2000; 22:55.

• Cines DB, Blanchette VS. Immune thrombocytopenic purpura. N Engl J Med 2002; 346:995.

• Provan D, Stasi R, Newland AC, et al. International consensus report on the investigation and management of primary immune thrombocytopenia. Blood 2010; 115:168.

• Blanchette V, Bolton-Maggs P. Childhood immune thrombocytopenic purpura: diagnosis and management. Hematol Oncol Clin North Am 2010; 24:249.

• Rodeghiero F, Castaman G, Dini E. Epidemiological investigation of the prevalence of von Willebrand's disease. Blood 1987; 69:454.

• Haitjema T, Westermann CJ, Overtoom TT, et al. Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease): new insights in pathogenesis, complications, and treatment. Arch Intern Med 1996; 156:714.

• Triplett DA, Brandt JT, Batard MA, et al. Hereditary factor VII deficiency: heterogeneity defined by combined functional and immunochemical analysis. Blood 1985; 66:1284.

• Monagle P, Barnes C, Ignjatovic V, et al. Developmental haemostasis. Impact for clinical haemostasis laboratories. Thromb Haemost 2006; 95:362.

• Hillman C, Lusher JM. Tests of blood coagulation technical points of clinical Hillman C, Lusher JM. Tests of blood coagulation technical points of clinical relevance. In: Acquired Bleeding Disorders in Children, Lusher JM, Barhart MI relevance. In: Acquired Bleeding Disorders in Children, Lusher JM, Barhart MI (Eds), Masson, New York 1981. Vol 2, p.107.(Eds), Masson, New York 1981. Vol 2, p.107.

• Payne BA, Pierre RV. Pseudothrombocytopenia: a laboratory artifact with potentially serious consequences. Mayo Clin Proc 1984; 59:123.

• Lippi U, Schinella M, Nicoli M, et al. EDTA-induced platelet aggregation can be avoided by a new anticoagulant also suitable for automated complete blood count. Haematologica 1990; 75:38.

• Lossing TS, Kasper CK, Feinstein DI. Detection of factor VIII inhibitors with the partial thromboplastin time. Blood 1977; 49:793.

• Exner T, Triplett DA, Taberner D, Machin SJ. Guidelines for testing and revised criteria for lupus anticoagulants. SSC Subcommittee for the Standardization of Lupus Anticoagulants. Thromb Haemost 1991; 65:320.

• Greenberg CS, Devine DV, McCrae KM. Measurement of plasma fibrin D-dimer levels with the use of a monoclonal antibody coupled to latex beads. Am J Clin Pathol 1987; 87:94.

• Lind SE. The bleeding time does not predict surgical bleeding. Blood 1991; 77:2547.

• Mammen EF, Comp PC, Gosselin R, et al. PFA-100 system: a new method for assessment of platelet dysfunction. Semin Thromb Hemost 1998; 24:195.

• Favaloro EJ, Facey D, Henniker A. Use of a novel platelet function analyzer (PFA-100) with high sensitivity to disturbances in von Willebrand factor to screen for von Willebrand's disease and other disorders. Am J Hematol 1999; 62:165.

• Dean JA, Blanchette VS, Carcao MD, et al. von Willebrand disease in a pediatric-based population--comparison of type 1 diagnostic criteria and use of the PFA-100 and a von Willebrand factor/collagen-binding assay. Thromb Haemost 2000; 84:401.

• Podda GM, Bucciarelli P, Lussana F, et al. Usefulness of PFA-100 testing in the diagnostic screening of patients with suspected abnormalities of hemostasis: comparison with the bleeding time. J Thromb Haemost 2007; 5:2393.

• Nichols WL, Hultin MB, James AH, et al. von Willebrand disease (VWD): evidence-based diagnosis and management guidelines, the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel report (USA). Haemophilia 2008; 14:171.

• Hayward CP, Harrison P, Cattaneo M, et al. Platelet function analyzer (PFA)-100 closure time in the evaluation of platelet disorders and platelet function. J Thromb Haemost 2006; 4:312.

• Montgomery RR, Gill JC, Scott JP. Hemophilia and von Willebrand's Disease. In: Montgomery RR, Gill JC, Scott JP. Hemophilia and von Willebrand's Disease. In: Nathan and Oski's Hematology of Infancy and Childhood, 6th, Nathan DG, Orkin SH, Nathan and Oski's Hematology of Infancy and Childhood, 6th, Nathan DG, Orkin SH, Ginsberg D, Look AT (Eds), WB Saunders, Philadelphia 2003. p.1547.Ginsberg D, Look AT (Eds), WB Saunders, Philadelphia 2003. p.1547.

• Gomez K, Bolton-Maggs P. Factor XI deficiency. Haemophilia 2008; 14:1183.

• Perry DJ. Factor VII Deficiency. Br J Haematol 2002; 118:689.

• Bajaj SP, Rapaport SI, Barclay S, Herbst KD. Acquired hypoprothrombinemia due to non-neutralizing antibodies to prothrombin: mechanism and management. Blood 1985; 65:1538.

• Furie B, Greene E, Furie BC. Syndrome of acquired factor X deficiency and systemic amyloidosis in vivo studies of the metabolic fate of factor X. N Engl J Med 1977; 297:81.

• Bomgaars L, Carberry K, Fraser C, et al. Development of factor V and thrombin inhibitors in children following bovine thrombin exposure during cardiac surgery: a report of three cases. Congenit Heart Dis 2010; 5:303.

• Chua JD, Friedenberg WR. Superwarfarin poisoning. Arch Intern Med 1998; 158:1929.

• Ockelford PA, Carter CJ. Disseminated intravascular coagulation: the application and utility of diagnostic tests. Semin Thromb Hemost 1982; 8:198.

• Bowman M, Hopman WM, Rapson D, et al. A prospective evaluation of the Bowman M, Hopman WM, Rapson D, et al. A prospective evaluation of the prevalence of symptomatic von Willebrand disease (VWD) in a pediatric primary prevalence of symptomatic von Willebrand disease (VWD) in a pediatric primary care population. Pediatr Blood Cancer 2010; 55:171.care population. Pediatr Blood Cancer 2010; 55:171.

• Park CH, Seo JY, Kim HJ, et al. A diagnostic challenge: mild hemophilia B with normal Park CH, Seo JY, Kim HJ, et al. A diagnostic challenge: mild hemophilia B with normal activated partial thromboplastin time. Blood Coagul Fibrinolysis 2010; 21:368.activated partial thromboplastin time. Blood Coagul Fibrinolysis 2010; 21:368.

• Duncan EM, Rodgers SE, McRae SJ. Diagnostic testing for mild hemophilia a in Duncan EM, Rodgers SE, McRae SJ. Diagnostic testing for mild hemophilia a in patients with discrepant one-stage, two-stage, and chromogenic factor VIII:C assays. patients with discrepant one-stage, two-stage, and chromogenic factor VIII:C assays. Semin Thromb Hemost 2013; 39:272.Semin Thromb Hemost 2013; 39:272.

• Lusher J, Pipe SW, Alexander S, Nugent D. Prophylactic therapy with Fibrogammin P Lusher J, Pipe SW, Alexander S, Nugent D. Prophylactic therapy with Fibrogammin P is associated with a decreased incidence of bleeding episodes: a retrospective is associated with a decreased incidence of bleeding episodes: a retrospective study. Haemophilia 2010; 16:316.study. Haemophilia 2010; 16:316.

• Hayward CP. Diagnostic approach to platelet function disorders. Transfus Apher Sci Hayward CP. Diagnostic approach to platelet function disorders. Transfus Apher Sci 2008; 38:65.2008; 38:65.

• Israels SJ, Kahr WH, Blanchette VS, et al. Platelet disorders in children: A diagnostic Israels SJ, Kahr WH, Blanchette VS, et al. Platelet disorders in children: A diagnostic approach. Pediatr Blood Cancer 2011; 56:975.approach. Pediatr Blood Cancer 2011; 56:975.

• Phillips DR, Agin PP. Platelet membrane defects in Glanzmann's thrombasthenia. Phillips DR, Agin PP. Platelet membrane defects in Glanzmann's thrombasthenia. Evidence for decreased amounts of two major glycoproteins. J Clin Invest 1977; Evidence for decreased amounts of two major glycoproteins. J Clin Invest 1977; 60:535.60:535.

• Nurden AT. Qualitative disorders of platelets and megakaryocytes. J Thromb Nurden AT. Qualitative disorders of platelets and megakaryocytes. J Thromb Haemost 2005; 3:1773.Haemost 2005; 3:1773.

• Warrier I, Lusher JM. Congenital thrombocytopenias. Curr Opin Hematol 1995; Warrier I, Lusher JM. Congenital thrombocytopenias. Curr Opin Hematol 1995; 2:395.2:395.

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