GENERAL PATHOLOGY

2. Disorders of Hemostasis

3. Primary Hemostasis
• The platelet contains lysosomes, granules,
and trilaminar plasma membrane,
microtubules.
• Granules are key in primary hemostasis
and contain ADP, Thromboxane, platelet
factor 4, adhesive and aggregation
glycoproteins, coagulation factors, and
fibrinolytic inhibitors

4. Primary Hemostasis
• Dependent on Platelets and Von
Willebrand Factor (vWF)
• Platelets gather and attach to vWF
• Platelets degranulate after attachment and
release ADP and Thromboxane which
attracts more platelets
• Forms a platelet plug
• Requires endothelial damage to adhere

5. Secondary Hemostasis
• Platelet aggregation initiates secondary
hemostasis through the coagulation
cascade
• Coagulation cascade is initiated by the
intrinsic or extrinsic pathway
• The final cascade results in fibrin
deposition cross-linking platelets and clot
formation

6. The Coagulation Cascade
Common Pathway

7. A word on clotting factors
• Vitamin K Dependent Factors
– Intrinsic Pathway : IX, X
– Common Pathway: II
– Extrinsic Pathway: VII
• All clotting Factors are produced in liver
except vWF/VIII
• VIII produced by the vascular endothelium
• Sites of heparin activity
– IIa, IXa, Xa ( major site), XIa, Platelet factor 3

8. A word on clotting factors
• Factor VIII – A factor by any other name?
– Same factor: 3 different activities
– VIII:C – antihemophilic or coagulation activity
– vWF – supports platelet adhesion and carries
VIII in the blood
– VIII:Ag – reacts with rabbit antibodies, relates
to measured plasma level rather than activity

9. Fibrinolysis
• The Ying to the Yang of clot formation
• Tissue Plasminogen activator (tPA)
– Released from endothelial cells
• Converts plasminogen to plasmin which
degrades fibrinogen and fibrin into fibrin
degradation products
• Cross linked fibrin is cleaved into D-
Dimers

10. Testing the hemostatic system
• CBC
– H/H drops often lag behind actual RBC loss due to
slow equilibration
• Blood smear
– Schistocytes and fragemented RBC- DIC
– Teardrop-shaped or nucleated RBC – Myelophthisic
disease
– Characteristic WBC morphologies seen in
thrombocytopenia in infectious mononucleosus,
folate, B12 deficiency, or leukemia

11. Testing the hemostatic system
• Platelet count
– Thrombocytopenia : Less that 100,000/mL
– Spontaneous bleeding possible: Less than
20,000/mL
– Count does not have anything to do with
functionality of platelet

12. Testing the hemostatic system
• Bleeding time
– Tests vascular integrity and platelet function
– Incision on volar aspect of the forearm 1mm
deep and 1 cm long
– BP cuff inflated to 40 mmHg
– Normal < 8 minutes
– Borderline 8-10 minutes
– Abnormal 10 + minutes
– Affected by ASA (permanent) and NSAIDs

13. Testing the hemostatic system
• Bleeding time
– Prolonged with platelet counts below 100,000
– When prolonged with platelet count over
100,000 suggests platelet dysfunction

14. Testing the hemostatic system
• Prothrombin Time
– Test of extrinsic and common pathways
– International Normalized Ratio used to
compensate for differences in thromboplastin
reagents
– Used for coumadin
– Elevated in patients with liver disease and
abnormalities in vitamin K sensitive factors

15. Testing the hemostatic system
• Partial Thromboplastin Time (PTT)
– Tests intrinsic and common pathway
– Average normal 25-29
– Factor levels usually less than 40% to be
affected
– Affected by heparin
– Can be effected by coumadin at supra-
therapeutic levels due to effects on the
common pathway

16. History and Physical
• Platelet Disorders
– More common in
Women
– Petechiae, Purpura,
mucosal bleeding
– More commonly
acquired
• Coagulation Disorder
– More common in Men
– Delayed deep muscle
bleeding,
hemarthrosis,
hematuria
– More commonly
congenital

17. Thrombocytopenia
• Usually mucosal bleeding
• Epistaxis, menorrhagia, and GI bleeding is
common
• Trauma does not usually cause bleeding

18. Thrombocytopenia
• Three mechanisms of Thrombocytopenia
– Decreased production
• Usually chemotherapy, myelophthisic disease, or
BM effects of alcohol or thiazides
– Splenic Sequesteration
• Rare
• Results from malignancy, portal hypertension, or
increased Splenic RBC destruction ( hereditary
spherocytosis, autoimmune hemolytic anemia)
– Increased Destruction

19. Thrombocytopenia
• Immune thrombocytopenia
– Multiple causes including drugs, lymphoma, leukemia,
collagen vascular disease
– Drugs Include
• Digitoxin, sulfonamindes, phenytoin, heparin, ASA, cocaine,
Quinine, quinidine, glycoprotein IIb-IIa antagonists
– After stopping drugs platelet counts usually improve
over 3 to 7 days
– Prednisone (1mg/kg) with rapid taper can shorten
course

20. Thrombocytopenia
• HIT
– Important Immunologic Thrombocytopenia
– Usually within 5-7 days of Initiation of Heparin
Therapy but late onset cases are 14-40 days
– Occurrence 1-5% with unfractionated heparin
and less than 1% with low molecular-weight
heparin
– Thrombotic complications in up to 50% of HIT
with loss of limb in 20% and mortality up to
30%

21. ITP
• Diagnosis of exclusion
• Associated with IgG anti-platelet antibody
• Platelet count falls to less that 20,000

22. ITP
• Acute Form
– Most common in children 2 to 6 years
– Viral Prodrome common in the 3 weeks prior
– Self Limited and > 90% remission rate
– Supportive Treatment
– Steroids are not helpful

23. ITP
• Chronic Form
– Adult disease primarily
– Women more often than men
– Insidious onset with no prodrome
– Symptoms include: easy bruising, prolonged
menses, mucosal bleeding
– Bleeding complications are unpredictable
– Mortality is 1%
– Spontaneous remission is rare

24. ITP
• Chronic Form
– Hospitalization common because of a
complex differential diagnosis
– Multiple treatments
– Platelet transfusions are used only for life
threatening bleeding
– Life threatening bleeding is treated with IV
Immune globulin (1g/kg)

25. TTPHUS
• Exist on a continuum and are likely the same
disease
• Diagnosed by a common pentad
– Microangiopathic Hemolytic Anemia: Schistocytes
membranes are sheared passing through
microthrombi
– Thrombocytopenia: More sever in TTP
– Fever
– Renal Abnormalities: More prominent in HUS: include
Renal insufficiency, azotemia, proteinuria, hematuria,
and renal failure
– Neurologic Abnormalities: hallmark of TTP 1/3 of
HUS: Sx of HA, confusion, CN palsies, seizure,coma

26. TTPHUS
• Labs
– PT, PTT, and fibrinogen are within reference
range
– Helmet Cells (Shistocytes) are common

27. TTPHUS
• HUS
– Most common in infants and children 6mo - 4
years
– Often associated with a prodromal diarrhea
– Strongest association to E. coli O157:H7 but
also associated with SSYC as well as multiple
virus
– Prognosis
• Mortality 5-15%
• Younger patients do better

28. TTPHUS
• HUS
– Treatment
• Mostly supportive
• Plasma exchange reserved for sever cases
• Treat hyperkalemia
• Avoid antibiotics with Ecoli
– May actually increase verotoxin production with TMP-
SMX
– May be helpful with cases of Shigella dysenteriae

29. TTPHUS
• TTP
– More common in adults
– Untreated mortality rate of 80% 1 to 3 months
after diagnosis
– Aggressive plasma exchange has dropped
the mortality to 17%
– Splenectomy, immune globulin, vincristine all
play a role in therapy

30. TTPHUS
• AVOID PLATELET TRANSFUSION
– May lead to additional microthrombi in
circulation
– Transfuse only with life threatening bleeding

31. Dilutional Thrombocytopenia
• PRBC are platelet poor
• Monitor platelet count with every 10 u
PRBC
• Transfuse when count below 50,000
• Get them upstairs before you transfuse 10
units PRBC

32. DIC
• A few harmless snowflakes working together
can create an avalanche of Destruction.

33. DIC
• Early recognition important secondary to
potentially devastating sequelae and effective
therapy
• DIC Sequence  Platelets and coagulation
factors consumed  Thrombin directly activates
fibrinogen Fibrin deposition  Fibrinolysis 
Inhibition of platelets and fibrin polymerization 
Decrease in inhibition levels
• Entire process leads to a massive consumption
of coagulation factors

34. DIC
• Life threatening combination of bleeding
diathesis with small vessel ischemia
• There are varying levels of acuity
• Recommended testing
– Peripheral Smear: Low platelets, schistocytes
– Platelet count: Low (<100,000)
– Pt, PTT, Thrombin Time: Prolonged
– Fibrinogen: Low
– Fibrin degredation products: zero to large

35. DIC
• Treatment
– Dependent on whether bleeding or ischemia
predominate
– If bleeding
• Platelets, FFP or Cryoprecipitate, and blood
recommended
– With Ischemia
• Heparin has a place in treatment
• Examples include Retained fetus, purpura
fulminans, giant hemangioma, and acute
promyelocytic leukemia

36. DIC
• Treatment
– Goal in ER is suspicion, aggressive pursuit of
diagnosis, understanding complications, and
rarely initiation of therapy

37. Coagulation Pathway Defects
• Hemophilia A
• Von Willebrand’s Disease
• Hemophilia B ( Christmas Disease)

38. Hemophilia A

39. Hemophilia A
• Variant form of Factor VIII
• 60 to 80 persons per million
• 70% Sex linked recessive
• Severity linked to level of VIII:C activity
– 1% Severe
– 1%-5% Moderate
– 5-10% mild ( little risk of spontaneous
bleeding)

40. Hemophilia A
• Bleeding can occur anywhere
– Deep muscles
– Joints
– Urinary Tract
– Intracranial
• Recurrent Hemarthrosis and progressive join
destruction are major cause of morbidity
• Intracranial bleed is major cause of death in all
hemophiliacs

41. Hemophilia A
• Mucosal bleeding is rare unless
associated with von Willebrands or
Platelet inhibition
• Unlike platelet defects Trauma initiates
bleeding
• Bleeding can occur usually by 8 hours but
as late as 1 to 3 days after trauma

42. Hemophilia A
• Management:
– Home therapy is increasingly common and
most report to ER only with complicated
problems or Trauma
– Hospitals should have files of known
hemophiliacs in the area
– Accepted therapy is with Factor VIII
replacement or VIII:C
– Newer preparation carry lower risk for Hep B
and Hep C transmission

43. Hemophilia A
• Management:
– Multiple guidelines for therapy institution
– Most important physician should believe a
patient saying they are bleeding and institute
early therapy

44. Hemophilia A
• Prophylaxis
– May require admission for anticipation of
delayed bleeding
– Candidates:
• Deep lacerations
• Soft tissue injury where hematoma could be
destructive ie: eye, mouth, neck, back, and spinal
column

45. Hemophilia A
• Treatment of haemophilic synovitis
– COX-2 important in Hemophiliacs because of
anti=inflammatory,and analgesic properties
but they do not affect the platelet fuction
– With withdrawl of rofecoxib from the market
celecoxib had become popular
– Study has shown that Celecoxib gives good
relief of synovitis without serious adverse
effects

46. Von Willebrand’s Disease
• Most common inherited bleeding disorder
• Without vWF the ability of platelets to
adhere is diminished
• VIII:C has diminished activity
• Bleeding sites are primarily mucosal
• Hemarthrosis is rare
• Menorrhagia and GI bleed are common

47. Von Willebrand’s Disease
• Factor VIII replacement is treatment of
choice
• FFP may be given in extreme
circumstances
• Desmopressin is only useful for specific
types of vWD and should only be give with
advice from hematologist

48. Hemophilia B (Christmas Disease)

49. Hemophilia B (Christmas Disease)
• Clinically indistinguishable from
hemophilia A
• Deficiency of factor IX
• Factor IX preparation used in treatment
• FFP and plasma prothrombin complex are
also useful
• Gene manipulation in animals shows
promising results for the future

50. Take home message
•All Bleeding stops….
Eventually

51. References
• Rosen’s
• Emedicine
• Celecoxib in the treatment of haemophilic
synovitis, target joints, and pain in adults
and children with haemophilia,
Haemophilia (2006), 12, 514-517