Bleeding and Clotting Flashcards
what is the most important predictor of bleeding risk?
history of bleeding
spontaneous hemarthroses are a hallmark of _______.
moderate and severe factor VIII (hemophilia A) and IX deficiency (hemophilia B)
- also seen in deficiencies of fibrinogen, prothrombin, and factors V, VII, and X
mucosal bleeding is suggestive of ________.
platelet disorders and VWD
what is a bleeding score?
used to predict patients more likely to have type I VWD
causes of easy bruising
abnormality of blood vessels or their supporting tissues
- Ehlers-Danlos
- Cushing’s syndrome
- chronic steroid use
- aging
epistaxis is the most common symptom in _______.
hereditary hemorrhagic telangiectasia and boys with VWD
bleeding with eruption of primary teeth is characteristic of ___________.
moderate and severe hemophilia
heavy menstrual bleeding can result in _______ anemia.
iron deficiency
heavy menstrual bleeding is most commonly seen in _________.
VWD, factor XI deficiency (hemophilia C), and symptomatic carriers of hemophilia
post-partum hemorrhage is delayed in _________.
type I VWD and symptomatic carriers of hemophilia A (factor VIII)
- VWF and factor VIII usually normalize during pregnancy
angiodysplasia of the bowel is associated with _______.
types 2 and 3 VWD
muscle and soft tissue bleeds are commin in _______.
factor VIII deficiency (hemophilia A)
________ is the major cause of bleeding-related death in patients with severe hemophilias (factor deficiencies).
CNS bleeding
aspirin and NSAIDs that inhibit COX-1 impair _________, and may cause bleeding
primary hemostasis
P2Y12 receptor inhibitors (clopidogrel, prasugrel, and ticagrelor) inhibit _________.
ADP-mediated platelet aggregation
is the risk of bleeding higher with NSAIDs or with P2Y12 receptor inhibitors?
P2Y12 receptor inhibitors
fish oil and omega-3 fatty acids impair _________.
platelet function
- increase expression of PGI3, a potent platelet inhibitor
- increase expression of TXA3, a weak platelet activator
vitamin E inhibits ________.
protein kinase C-mediated platelet aggregation and NO production
liver failure results in _________.
combined factor deficiencies
- because all coagulation factors are made in the liver
defects of platelet adhesion inlcude:
- VWD
- Bernard-Soulier syndrome (lacks GPIb)
defects of platelet aggregation include:
- Glanzmann thrombasthenia (lacks GPIIb/IIIa)
- afibrinogenemia
defects of platelet secretion include:
- aspirin-like platelet defects
- granule storage pool defects
bleeding rarely occurs with platelets at ________.
> 50K
- surgery can be performed as long as the patient has at least 50-80K platelets
the major risk factor for for arterial thrombosis is ________.
atherosclerosis
the major risk factors for venous thrombosis are ________.
- immobility
- surgery
- malignancy
- medications
- obesity
- genetics
the most important point in history related to venous thrombosis is _______.
whether the event was idiopathic or precipitated
- in patients without malignancy, an idiopathic event is the strongest predictor of recurrence of VTE
PFA-100
measures platelet-dependent coagulation
- prolonged in patients with some (not all) inherited platelet disorders
thromboelastography
useful in guiding intraoperative transfusion
- not used in dx of disorders of hemostasis or thrombosis
prothrombin time (PT)
measures the extrinsic clotting cascade
factor I (fibrinogen), II (prothrombin), V, VII, and X
- sensitivity varies by lab–use INR
when testing blood, _________ can give a false value
elevated hematocrit (> 55%)
- this is d/t decreased plasma-to-anticoagulant ratio
INR
standard unit of sensitivity of certain thromboplastins to vitamin K-dependent clotting factors
- sensitivity of thromboplastin varies by lab, producing different PT times per lab
partial thrombin time (aPTT)
measures the intrinsic clotting cascade
factor I (fibrinogen), II (prothrombin), V, VIII, IX, X, XI, XII (Haegaman factor), prekallikrein, and high-molecular-weight kininogen
- sensitivity varies by the phospholipids used in each lab
mixing studies are used for _________.
distinguishing between factor deficiency and an inhibitor
- normal plasma is mixed with the patient’s plasma and aPTT or PT are measured
if the aPTT corrects in a mixing study:
it indicates and isolated factor deficiency
if the aPTT fails to correct during a mixing study:
- there is lupus anticoagulant present or
- there are Abs against certain clotting factors or
- there are other inhibitors such as heparin, fibrin split products, or paraproteins
what is a lupus anticoagulant?
antibodies to phospholipids that interfere with phospholipid-dependent coagulation tests
lupus anticoagulants can be detected by _______.
dilute Russel viper venom test (dRVVT) and tissue thromboplastin inhibition (TTI)
diagnosis of lupus anticoagulant requires:
- prolongation of a phospholipid-dependent coagulation test (LA-PTT, dRVVT, or TTI)
- lack of correction when mixed with normal plasma, and correction with the addition of activated platelet membranes or certain phospholipids
thrombin time measures
fibrinogen** conversion to **fibrin
thrombin time is prolonged with:
- low fibrinogen levels or qualitatively abnormal fibrinogen
- the presence of heparin
- prsence of dabigatran (direct thrombin inhibitor)
measurement of anti-factor Xa activity is used to assess:
- LMWH levels
- direct measurement of unfractionated (regular) heparin activity
- activity of direct Xa inhibitors (rivaroxaban, apixaban, edoxaban)
anti-thrombin is decreased _________.
by heparin and in the setting of acute thrombosis
what causes protein C and S levels to increase/decrease?
- increase during acute thrombosis
- decreased by warfarin
venous stasis (not thrombosis) typically presents with _______.
lower extremity edema and achy pain in the legs
therapy options for venous stasis (not thrombosis) include:
- compression stockings
- unna boots
- aspirin
what are the underlying risk factors for DVT/PE?
- venous stasis
- hypercoagulability
- endothelial damage
the initial and most important step in evaluating possible DVT is ________.
estimating the clinical liklihood of disease
D-dimer tests should be performed in patients with ________.
low liklihood of DVT
what rules out DVT?
- low clinical probability +
- negative D-dimer
if D-dimer is positive or clinical likelihood of DVT is high, what should be done?
duplex ultrasonography
who should recieve prophylaxis for venous thromboembolism?
- patients with known thromboembolic conditiation and an indication for treatment
- hospitalized patients with VTE risk factors
symptoms of PE include:
- dyspnea
- pleuritic chest pain
- cough
- hemoptysis
- tachypnea
- crackles
- tachycardia
- accentuated pulmonic component of S2
what rules out PE?
- low clinical probability +
- negative D-dimer
should D-dimer be used in patients with a high liklihood of PE?
NO
what tests should be done in a patient with a high liklihoood of PE?
- contrast-enhanced CT
- V/Q scanning
- this is the only test that can rule out PE
Wells criteria for DVT
high (> 3), moderate (1-2), low (0)
- active cancer - 1
- paralysis/immobilization - 1
- bedridden for >3 d or majory surgry within 4 w - 1
- entire leg swollen - 1
- tenderness along deep vein - 1
- calf swelling > 3 cm - 1
- unilateral pitting edema - 1
- collateral superficial veins - 1
- alternative dx more likely thanPE - (-)
Wells criteria for PE
high (> 6), moderate (2-6), low (< 2)
- clinical evidence of DVT - 3
- PE is most likely dx - 3
- HR > 100 - 1.5
- immobile > 3 d or surgery within 4 w - 1.5
- previous DVT/PE - 1.5
- hemoptysis - 1
- malignancy - 1
how long should you anticoagulate DVT or PE caused by:
- transient risk factor
- cancer
- unprovoked
- recurrent unprovoked
- underlying thrombophilia
- antiphospholipid Ab
3 months, then
- transient risk factor - 3 months
- cancer - as long as cancer is active (enoxaparin)
- unprovoked - indefinite (w ASA) if necessry
- recurrent unprovoked - indefinite
- underlying thrombophilia - indefinite
- antiphospholipid Ab - indefinite
what patients are at high risk for DVT/PE post-op?
> 3 intrinsic risk factos
- ortho sx, abdominal/pelvic sx, spinal sx, major trauma
what patients are at intermediate risk for DVT/PE post-op?
BMI > 30, age > 50
- non-ambulatory, infection, active malignancy, history of VTE
what patients are at low risk for DVT/PE post-op?
minor procedures in healthy patients < 40 yo
- ambulatory, length of stay < 24 hrs
how to prophylax abdominal/pelvic sx patients
enoxaparin for 4 weeks
how to prohylax ortho sx patients
enoxaparin/fondaparinux/DOACs/warfarin for 10 days min
- 35 days for hip
- 12 days for knee
how to prophylax bariatric sx patients
enoxaparin 2 q d
what is the treatment for TTP?
plasmapheresis
what is the treatment for VWD?
- cryoprecipitate - replaces VWF
- DDAVP - causes release of VWF from endothelium
hereditary hemorrhagic telangiectasia
(osler-weber-rendu syndrome)
thinning of vessel walls d/t autosomal dominant mutation in endoglin
- –> telangiectasias, AVMs, and aneurysmal dilations
what is the most common cause of hypercoaguable state in patients with protein C and S deficiency?
warfarin therapy
