8/20- Acquired Bleeding Disorders Flashcards
What are the 3 most common causes of acquired bleeding disorders? Others?
- DIC
- Liver failure
- Vitamin K deficiency
Also:
- Factor specific inhibitor
- Trauma
- Dilutional coagulopathy
Type of bleeding varies with etiology
- What symptoms/type of bleeding are common in platelet defects (thrombocytopenia and function defect) and coagulopathy?
Platelet defects (thrombocytopenia and function defect):
- Petechiae characteristic
- Superficial bruising characteristic (small, multiple)
- Sometimes positive family Hx
- Rarely hemarthrosis and deep hematomas
Coagulopathy:
- Hemarthroses and deep hematomas are characteristic
- Superficial bruising is common (large, solitary)
- Family Hx is common
- Petechiae are rare
Local vs. systemic bleeding (what do they suggest?)
- Single area suggests a structural defect
- Multiple sites suggest a systemic defect
PE of a bleeding patient involves what?
- Determine all sites of hemorrhage
- Determine presence of jaundice, hepatomegaly, splenomegaly, or telangiectasias
Platelet abnormalities, von Willebrand disease, vascular defects
- Mucocutaneous bleeding (nose bleed, menorrhagia)
- Petechiae
Coagulation factor defects
- Intramuscular or intra-articular bleeding
- Mucocutaneous bleeding (nose bleed, menorrhagia)
- No petechiae
What screening lab tests should be done on a bleeding pt?
- CBC (Hb,Hct, WBC, platelet count, WBC differential)
- PT, PTT, and fibrinogen
- Platelet function study
What are some acquired coagulation disorders? Inherited?
Acquired:
- DIC
- Liver disease
- Vitamin K deficiency
- Dilutional coagulopathy
- Trauma
- Factor specific inhibitor
Congenital:
- Hemophilia A
- Hemophilia B
- Von Willebrand disease
- Other
Describe coagulation disorders in regard to liver disease
- Decreased synthesis of all clotting factors except factors VIII and XIII
- Decreased clearance of fibrin degradation products (= FSP) or D-dimer
- Thrombocytopenia (2o to congestive splenomegaly and decreased thrombopoietin)
- Increased fibrinolysis, low-grade DIC, vitamin K deficiency (with biliary disease and alcoholism)
What would key lab results be in liver disease?
- Prolonged PT and PTT
- Low fibrinogen level (fibrinogen synthesis often maintained except in liver failure)
- Low coagulation factor levels (commonly monitored by FV and FVII as surrogates for the liver)
- Factor VIII is not decreased
Management for bleeding risk due to liver disease?
Transfusion therapy:
Fresh frozen plasma (FFP)
- FFP contains all coagulation factors, VWF multimers, and fibrinolytic control proteins, as well as plasminogen and anticoagulants.
Cryoprecipitate: Fibrinogen (+ factor VIII, vWF, factor XIII, fibronectin)
Platelets
Case)
A 46 yo man with severe liver failure awaiting liver transplant
PT: 36.3 s, PTT: 48.5 s, fibrinogen 98 mg/dL
D-dimer 2.8 ug/mL (moderate positive)
Factor V 4%, factor VII 2%, factor VII 169%
Classic
What is DIC? What processes does it involve?
Disseminated Intravascular Coagulation
Coagulation activation leading to fibrin formation and consumption coagulopathy
- Fibrin formation induces thrombosis
- Consumption coagulopathy induces bleeding
No primary DIC!
- It is always secondary to clinical conditions (can get bleeding and thrombosis at the same time)
What are some predisposing conditions for DIC?
Three most common causes:
- Infection: Gm- (endotoxin); sepsis
- Malignancy: acute promyelocytic leukemia (M3)- tissue factor in promyelocytes
- Obstetric complication: abruptio placenta, missed abortion, eclampsia, and amniotic fluid embolism
Other causes:
- Massive trauma
- Heat stroke
- Burns
- Extensive surgery
Pathophysiolog of DIC
Trigger of coagulation activation:
- Disturbance of endothelial cells
- Entry of tissue factor into circulation
- Circulating microvesicles
Fibrinolysis always present to a variable degree
- Fibrin and fibrinogen are degraded by plasmin
Fibrin degradation or split products (FDP or FSP) accumulate; these inhibit stable clot formation and platelet function -> bleeding
Diagnosis of DIC? Lab findings?
Based on clinical and laboratory findings. Patients must have a predisposing condition.
- DIC is always secondary. No primary DIC.
Typically, the bleeding is diffuse; e.g., a patient in the SICU who’s oozing blood from multiple sites, like IVs, arterial lines, tracheostomy, chest tube, Foley catheter, and other drains.
- Localized bleeding may be surgical bleeding
Labs:
- PT should be prolonged and D-dimer should be positive!!
- PTT may be prolonged but can be normal or even shortened (“Paradoxical shortening of PTT”); measure of FVIII which can be really increased?
- Platelet count may be decreased but can be normal or increased as platelet being an acute phase reactant.
- Fibrinogen may be decreased but can be normal or increased as an acute phase reactant.
- Schistocytes may be present on the peripheral blood smear.
What is shown here?
PBS with Schistocytes (fragmented RBCs)
Describe gamma-carboxylation of prothrombin?
What will you see if this process is not working (measurable)?
- Vitamin K is a cofactor necessary for this process (gamma-carboxylation of prothrombin precursor)
- In its absence, precursor PIVKA could be detected in the serum/plasma
