Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pathology Term 3 > Week 6 - HAEMOSTASIS > Flashcards

Week 6 - HAEMOSTASIS Flashcards

Diagnosing Hemostatic Disorders, Bleeding Disorders, DIC, Hypercoagulability, Transfusion

1
Q

What is placed in samples of blood and why?

A
  • blood sample in sky blue cap

- SODIUM CITRATE –> halts coagulation process and preserves coagulation factors (by blocking calcium)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is normal bleeding time?

A

<10 mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does prothrombin time (PT) measure and when is it prolonged?

A
  • tests extrinsic and common pathway
  • prolonged in acquired disorders:
  • vit. K deficiency
  • liver disorders
  • warfarin Tx.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is INR?

A

International Normalised Ratio

  • standardised PT value
  • correction for different thromboplastin reagents used (animal product)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does an INR of 1 mean?

A

-pts. plasma has the same extrinsic pathway as that of a normal plasma corrected for various commercial reagents

** high INR = longer it takes for blood to clot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is suspected if both PT + PTT are increased?

A

pathology is in the COMMON pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does partial thromboplastin time (PTT) measure and when is it prolonged?

A
  • intrinsic + common pathways
  • prolonged in congenital bleeding disorders
  • hemophilias (A + B)
  • von Willebrand disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When is thrombin time performed and what does it test?

A
  • when both PT + PTT are abnormal
  • tests fibrinogen levels (COMMON pathway)
  • *useful in DIC
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When is FDP/D-Dimer increased?

A

DIC (clot breakdown occurring)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the test priniples for PT + PTT?

A

PT:
-animal tissue thromboplastin (with sodium citrate) –> FVIIa –> CLOT

PTT:
-kaolin + cephalin –> FXIIa –> FVIIIa/FIXa –> CLOT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is suspected if a pts. plasma with increased PT/PTT is mixed with normal plasma and the PT/PTT corrects?

A

clotting factor deficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is suspected if pts. plasma with increased mixed with normal plasma and the PT/PTT does not correct?

A
  • PT/PTT inhibited
  • therefore –> coagulation inhibitors

i.e. heparin; specific factor inhibitor (FVIII or FV); non-specific inhibitor (lupus anticoagulants)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a thromboelastogram (TEG)?

A
  • quick test before and during major surgery
  • measures clot formation, strength + lysis
  • global assessment of hemostatic function
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the lab. findings (Plt count, BT, PT, PTT) for common hemostatic disorders:

  • ITP?
  • vWD?
  • Hemophilia?
  • DIC?
  • Aspirin?
  • Warfarin/Heparin?
A

ITP:

  • plt count –> low
  • BT –> high
  • PT –> normal
  • PTT –> normal

vWD:

  • plt count –> normal
  • BT –> high
  • PT –> normal
  • PTT –> high

Hemophilia:

  • plt count –> normal
  • BT –> normal
  • PT –> normal
  • PTT –> high

DIC:

  • plt count –> low
  • BT –> high
  • PT –> high
  • PTT –> high

Aspirin:

  • plt count –> normal
  • BT –> high
  • PT –> normal
  • PTT –> normal

Warfarin/Heparin:

  • plt count –> normal
  • BT –> normal
  • PT –> high
  • PTT –> high
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where is vWF located and what does this mean for its function?

A

Subendothelial region
-aidss plt. adhesion to endothelial defects

Plasma
-carries FVIII and prevents early degeneration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Clinically, what is the commonest bleeding disorder?

A

Thrombocytopenia

-commonest cause of bleeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Outline plt production

A

thrombopoietin stimulates endomitotic synchronous nuclear replication of megakaryocytes –> cytoplasmic granulation –> cytoplasmic fragments separate out as platelets (loaded w coag. factors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the lifespan of plts and what results afterwards?

A

8 - 9 days
-either involved in hemostasis
OR
-destroyed in spleen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe typical bleeding characteristics in thrombocytopenia

A

-superficial bleeding (capillary damage)

Clinically:

  • petechiae
  • purpura
  • ecchymosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What hemostatic factors are contained in platelets?

A
  • ADP
  • calcium
  • vWF
  • PF4
  • fibrinogen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the causes of thrombocytopenia?

A
  • autoimmune, drugs, infections - viral
  • BM suppression
  • megaloblastic anemia
  • aplastic anemia
  • increased consumption (DIC, TTP + HUS)
  • Plt function disorders: - less common
  • vWD, Bernard Soulier syndrome, Glauzman thrombasthenia
  • plts are present but NOT functional
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is normal plt. count and what counts result in excess + spontaneous bleeding?

A

normal: 150 - 250 x 10^9/L
excess bleeding: <50 x 10^9/L (i.e. after trauma/surgery)
spontaneous bleeding: <20 x 10^9/L (severe and life-threatening)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is ITP and what are the clinical features?

A
  • immune thrombocytopenic purpura
  • autoimmune disorder –> IgG Ab against plts –> plts destroyed in spleen –> thrombocytopenia

CF’s:

  • petichiae
  • purpura
  • ecchymosis
  • easy bruising
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the 2 types of ITP?

A
  1. acute
    - children, post-infection, self-limited
  2. chronic
    - F (20-40yrs)
    - chronic + severe
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the lab. findings in ITP?

A

CBC:

  • thrombocytopenia
  • giant immature plts

PT/PTT:
-normal (coagulation is normal)

BM:
-immature megakaryocytes increased –> compensatory in response to loss of plts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the common causes of viral haemorrhagic fevers and what is the pathogenesis?

A

Causes:
-dengue, chikungunya, measles, malaria, yellow fever, Ebola, etc

Patho:
-endothelial damage by virus +/or anti-viral Abs –> vasculitis –> plt. activation –> thrombocytopenia –> bleeding

*PT/PTT usually normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What coag. factor deficiency is present in hemophilia A + B?

A

A –> FVIII

B –> FIX

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What type of genetic abnormality is hemophilia + what does this mean?

A

x-linked recessive

  • increased in females (carriers)
  • increased in males (affected)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

True or False?

-hemophilia A/B results in petichiae/purpura/ecchymosis

A

False

  • as coag. factors (NOT plts) are affected, bleeding is deep NOT superficial
  • increased wound bleeding and deep hematoma
  • joint bleeds (skin/mucosal bleeding in severe)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the therapy for hemophilia?

A

DDAVP
-releases factors from endothelium

FVIII/FIX concentrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where is vit. K found and what is it necessary for?

A
  • green leafy veggies + intestinal bacteria

- necessary for carboxylation of factors 2, 7, 9, 10 in the liver

32
Q

What are the causes of vit. K deficiency?

A
  • diet
  • drugs
  • liver disease
  • warfarin inhibits vit. K action (to prevent thrombophilia)
33
Q

Why is PT increased and PTT normal until late in vit. K deficiency/warfarin Tx.?

A

-factor VII (extrinsic pathway - PT) has the shortest half-life –> warfarin affects this factor first

34
Q

What is vWD?

A
  • von willebrand disease
  • low vWF –> deficiency of both platelet adhesion to damaged endothelium AND deficiency in FVIII
  • both plt. and coag. = abnormal –> superficial and deep bleeds
35
Q

What is vWF produced by?

A

both plts. and endothelial cells

36
Q

True or False?

-vWD is an x-linked recessive disorder

A

False

  • autosomal dominant
  • both males + females affected
37
Q

Why is there increased BT despite normal plt. count in vWD?

A
  • low vWF in vWD

- plts cannot function without vWF (cannot bind to collagen in endothelial defects) –> increased BT

38
Q

Why is normal PT but PTT increased in vWD?

A
  • vWF carries + protects FVIII

- no vWF in vWD = FVIII deficiency –> increased PTT

39
Q

What is therapy for vWD?

A

fresh frozen plasma (FFP)/cryoprecipitate which contain vWF

40
Q

What is DIC?

A

Disseminated Intravascular Coagulation

-systemic activation of coagulation –> consumption of coag. factors + plts –> severe bleeding

41
Q

What is the cause/etiology of DIC?

A

-infection/trauma/cancer
-release of tissue factor into circulation –> trauma
OR
-widespread endothelial damage –> infection

42
Q

What is the pathogenesis of DIC?

A

activation of coagulation –> microthrombi –> infarction –> consumption of hemostatic factors –> bleeding –> activation of fibrinolysis –> excess fibrin breakdown

43
Q

What are the clinical features of DIC?

A
  • thrombosis
  • severe bleeding
  • shock
  • renal failure
44
Q

What are lab Dx. for DIC?

A
  • decreased coag. factors (deep) + plts (superficial) –> ALL tests abnormal
  • FDP + D-Dimer increased
  • life-threatening
45
Q

What are the 2 clinical syndromes of thrombotic microangiopathy? and how do they differ to DIC?

A
  1. thrombotic thrombocytopenic purpura (TTP) - adults
  2. hemolytic uremic syndrome (HUS) - children
  • unlike DIC, coagulation factors remain normal or mild decrease
  • ONLY activation of plts.
46
Q

What is thrombotic microangipathy?

A
  • widespread thrombosis in microcirculation leading to organ infarctions + microangipathic hemolytic anemia (fragmented RBCs)
  • TTP + HUS
47
Q

What are the predominant consequences of TTP + HUS?

A

TTP –> neurologic defects/strokes

HUS –> kidney failure

48
Q

What enzyme is deficient in TTP? What is its normal function and how can one be deficient in it?

A

ADAMTS13

  • protease which normally breaks down vWF multimers to stop plt activation
  • essentially, TTP is opposite to vWD as there is increased vWF –> increased plt. activation + loss –> extensive systemic thrombosis

Acquired:
-Ab to ADAMTS13 –> deficiency

Congenital:
-mutation –> ADAMTS13 deficiency

49
Q

How is TTP treated?

A

-plasma exchange with fresh frozen plasma or cryoprecipitate to remove Ab or replace ADAMTS13 (previously 90% fatal)

50
Q

True or False?

ADAMTS13 levels are decreased in childhood HUS

A

False

  • normal levels
  • E. coli/shigella infection + shiga toxin causing extensive endothelial damage –> plt activation
51
Q

What is adult HUS?

A

TTP with predominant renal failure

52
Q

What are the natural anticoagulants?

A

Protein C + S –> inhibit FVIIIa + FVa

Heparin –> inhibits thrombin (FIIa)

53
Q

What is the most common anticoagulant drug + what does it inhibit?

A

warfarin

  • inhibits vit. K reductase
  • decreased vit. K dependent coag factors (2, 7, 9, 10)
54
Q

What are the hereditary causes of hypercoagulability?

A

Factor V Leiden mutation

  • Factor V is resistant to protein C inhibition
  • uncontrolled factor V activation

Protein C/S deficiency
-decreased inhibition of FVa + FVIIIa

55
Q

What are acquired causes of hypercoagulability?

A
  • trauma, inflamm., cancer
  • heart disease, atherosclerosis, HTN, DM, etc
  • stasis of blood
  • drugs, Abs –> antiphospholipid antibody syndrome (AAS)
  • *Virchow’s Triad (Blood - BV - Blood Flow)
56
Q

What are clinical features of hypercoagulability?

A

THROMBOSIS

  • vein –> DVT (potential PE)
  • artery –> thrombosis; stroke
  • placenta (pregnancy) –> abortion
57
Q

What is AAS + what Abs are involved?

A

antiphospholipid antibody syndrome

  • Abs to plt. phospholipids:
    1. anticardiolipin
    2. lupus anticoagulant

N.B. following infection in children/pts with autoimmune dis./drugs

58
Q

What % of SLE pts develop AAS?

A

30%

59
Q

How does AAS differ clinically from in the laboratory?

A
  • clinically, autoantibodies activate coagulation in body

- in lab. autoantibodies bind to phospholipid part of reagent –> prolong PTT

60
Q

What is the lab Dx. of AAS?

A
  • normal PT but prolonged PTT –> looks like deficiency but is hypercoagulability
  • PTT remains prolonged even after adding 50% normal plasma –> unlike factor deficiency
61
Q

What is contained in fresh frozen plasma + cryoprecipitate and what are the indications for transfusion?

A

FFP –> all coag. facotrs –> bleeding
cryoprecipitate –> factor 1, 8, 9, vWF –> specific deficiency
*factor 1 = fibrinogen

62
Q

What is the shelf-life of platelet concentrate?

A

5 days

63
Q

Why are RBCs easier to match in transfusions compared to WBCs/plts?

A

WBCs/plts

  • have HLA Ag
  • difficult to match
  • more reactions/rejections

RBCs

  • no HLA Ag
  • only major blood groups
64
Q

What are the clinically significant blood group systems + why?

A

ABO + Rh

-naturally occurring strong IgM antibodies

65
Q

What is the commonest + rarest blood group?

A 
commonest = O+
rarest = AB-
66
Q

What is Landsteiner Law?

A

when a person has a blood group Ag, corresponding Ab is ABSENT from plasma

67
Q

What is the substance known as on red cell membranes that is modified by A, B, O genes?

A

H substance

-A, B, O genes control synthesis of enzymes that modify red cell membrane glycolipid (H substance)

68
Q

What are the 3 genes involved in Rh system?

A
  1. C/c
  2. D/d
  3. E/e

Rh+ = D –> strong/clinically significant
Rh- = d
-little letter denotes negative

69
Q

What is bombay blood group?

A
  • absence of H substance in ABO blood system
  • anti-H antibodies present
  • clinically seen as O group
70
Q

Compare IgG vs. IgM

A

IgG:

  • small, monomer
  • optimum reaction @37degrees
  • able to cross placenta
  • coat cells –> no agglutination
  • main type produced following preg./transfusion (alloantibodies)

IgM:

  • large, pentamer
  • optimum reaction @-20degrees
  • does NOT cross placenta
  • agglutinates
  • often “naturally occuring” Abs - ABO blood group
71
Q

What is a major + minor cross match?

A 
major = donor RBC with pt. plasma
minor = donor plasma with pt. RBC

–> to prevent hemolytic transfusion reaction

72
Q

What is the purpose of Ab screening?

A
  • many other Ags on donor RBC
  • additional Ab screening done to detect alloantibodies in pt. plasma with known reagent RBC (post transfusion/pregnancy)
73
Q

What are the 3 main transfusion reactions and what are each caused by?

A
  1. allergic –> plasma proteins
  2. febrile –> Abs to donor leucocytes
  3. hemolytic –> immune/mismatch
74
Q

What are the Sx. of hemolytic transfusion reaction?

A
  • hemoglobinuria
  • chest pain
  • apprehension
  • lower back pain
  • fever/chills
  • decr. BP/incr. RR
  • acute kidney failure*
75
Q

Why is bacterial contamination of blood products more common with plts?

A

They are kept at increased temp. (22degrees)

76
Q

What is “lookback program”?

A

-identify + notify recipients of blood products from previously negative/screened donor who is now positive for infectious agent

Pathology Term 3 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions