Transfusion Medicine and Coagulation Disorders Flashcards
(17 cards)
A 20 year old male has an inherited bleeding disorder characterized by a prolonged bleeding time, a normal platelet count, a variably prolonged PTT, and a normal PT. The most likely diagnosis is:
a. Factor VII deficiency
b. Factor VIII deficiency
c. Factor IX deficiency
d. vonWillebrand disease
d. vonWillebrand disease
The PT measures the extrinsic pathway and the PTT measures the intrinsic pathway. PT is prolonged if teh following factors are low or depleted: VII, X, V, II.
PTT is prolonged if the following factors are low or depleted: XII, XI, X, IX, VIII, V, II and fibrinogen.
In factor VIII deficiency, the bleeding time would be normal, and this is the easiest way to differentiate the VIII deficiency vs von willebrand.
The most effective component to treat a patient with fibrinogen deficiency is:
a. fresh frozen plasma
b. platelets
c. cryoprecipitate AHF
d. fresh whole blood
c. cryoprecipitate AHF
Select which results correlate with a Factor VII deficiency:
a. a prolonged APTT and normal PT
b. a prolonged APTT and prolonged PT
c. a normal APTT and prolonged PT
d. a prolonged PT and abnormal bleeding time
c. a normal APTT and prolonged PT
In a pre-surgical workup, a patient’s platelet count was normal and the PT, APTT and thormbin time were all slightly elevated. Inspection of teh clot from teh PT and APTT shows poor clot formation. Which factor is most likely deficient?
a. Factor X
b. Factor VIII
c. Fibrinogen
d. Prothrombin
c. Fibrinogen
A KB test indicates 10 fetal cells per 1000 adult cells. For a woman with 5000 ml of blood volume, the proper dose of RHIG is:
a. one regular dose vial
b. two regular dose vials
c. one microdose vial
d. two microdose vials
b. two regular dose vials
The calculation is as follows: (#fetal cells x maternal blood volume) divided by the # maternal cells = volume of fetomaternal hemorrhage.
Therefore the calculation for this problem is (1x5000) divided by 100 = 50 ml FMH
Each regular dose of RHIG will counter 30 ml of WB and 15 ml of packed RBCs. Therefore, now divide the FMH volume by 30 to determine the number of vials 50/30=1.6
Round up to the next highest number, so you would administer two vials, then add an additional vial as a precaution.
This is not wrong to do, but it is an institutional policy, not a standard practice. Therefore for the SBB exam, don’t add the extra vial in your calculations.
A group O negative mother with an anti- titer of 1:512 delivers a baby boy who is A negative, with a 1+ DAT. The KB test is performed, and the fetal bleed is determined to be 25 ml of whole blood. The institutions policy is to add an extra vial RHIG to ALL doses. Which statement below best describes the correct dose of RHIG for this mother?
a. 2 regular dose vials of RHIG
b. regular dose vials of RHIG
c. do not administer RHIG
c. do not administer RHIG
Do not administer RHIG. The baby is RH negative, therefore the Mom is not a candidate.
Ristocetin co-factor activity is a functional assay for which factor?
a. Factor VIII
b. Factor VII
c. Factor IX
d. von Willebrand factor
d. von Willebrand factor
Mucosal bleeding is a characteristic of all of the following except:
a. decreased platelet count
b. a defect in platelet function
c. von Willebrand disease
d. Hemophilia A
d. Hemophilia A
Mucosal bleeding is typically due to platelet problems, and not seen in coagulation factor deficiencies. Hemophilia A is a factor deficiency, not a platelet disorder. Again, the use of the word EXCEPT should be noted here.
A 71-kg patient in disseminated intravascular coagulation (DIC) has a hematocrit of 30% and a fibrinogen level of 90 mg/dL. How many units of Cryoprecipitated AHF should be administered to achieve a fribrinogen level of 200 mg/dL?
a. 3 units
b. 10 units
c. 14 units
d. 30 units
c. 14 units
Standard empiric dosing consists of 10 units followed by an assessment of effect through coagulation testing. If Cryo AHF is being used to replace fibrinogen, the number of units necessary to reach this goal can be calculated. Similarly, if it is being used to replace Factor VIII, a dose can be calculated.
The calculation to determine the dose of Cryo AHF to react a desired fibrinogen level is as follows:
65 mL/Kg is the average blood volume of a person
Weight (kg) x 65 mL/kg = blood volume (mL)
71 Kg x 65 mL/Kg = 4615 mL
Blood volume (mL) x (1.0 - hematocrit) = plasma volume (mL)
4,615 mL x (1.0 - 0.30) = 3,230.5 mL
Desired fibrinogen level in mg/dL - initial level) x plasma volume/100 mL/dL = mg fibrinogen needed.
(200 mg/dL - 90 mg/dL) x 3,230.5/100 dL = 110 mg/dL x 32.306 dL = 3,553.66
mg fibrinogen needed/250 mg fibrinogen per bag = number of bags required
3,553.66 mg fibrinogen needed/250 mg per bag = 14 units of cryoprecipitate.
A patient who has been taking large dose of IV penicillin presents with a positive DAT and hemolytic anemia. The following results are obtained:
SCI =0
SCII = 0
SCIII = 0
AC = 2+
DAT: POLY = 2+ IgG = 2+ C3 = 2+
Eluate:
SCI =0
SCII = 0
SCIII = 0
What is the next best step?
a. Test the eluate and serum against penicillin coated cells.
b. Treat the patient cells with penicillin and perform and auto-adsorption.
c. absorb the eluate with penicillin coated cells.
d. Test the screening cells at IS and RT.
a. Test the eluate and serum against penicillin coated cells.
A patient who is taking large amounts of IV penicillin can develop an antibody against the penicillin drug hapten. The antibody can only be detected by testing the eluate and serum with penicillin coated cells.
The question asks you to identify the BEST step. If we just test the eluate with penicillin coated cells, then we might know that the antibody coating the cells is penicillin specific. However, if we test both the serum and eluate, then we can know what is in BOTH the serum and on the cells. When choosing the BEST step, pick the option that will give you the most information the quickest.
An adult female arrives in the Emergency Room. She is light headed, pale and appears to have some neurological impairment. Review the laboratory results below, correlate them with the patient history, and then select the answer below that is the most likely diagnosis for this case.
Lab Results:
Hgb: 10 gm/dL
Hct: 29%
Reticulocytes: 5.1%
Platelet Count: 10,000/ul
PT: 12 seconds
APTT: 29 seconds
Thrombin Time: 16 seconds
Fibrinogen: 250 mg/dL
FDP: 2/1 mg/L
LDH: 380 U/L
Haptoglobin: 20 mg/dL
Indirect Bilirubin: 3.5 mg/dL
Creatinine: 0.3 mg/dL
DAT: Negative
Blood Culture: No growth at 48 hours
a. Hemolytic Uremic Syndrome (HUS)
b. Thrombotic Thrombocytopenia Purpura (TTP)
c. Autoimmune Hemolytic Anemia (AIHA)
d. Disseminated Intravascular Coagulation (DIC)
b. Thrombotic Thrombocytopenia Purpura (TTP)
There is a lot of information in this problem and it is common for the SBB exam to give you values without normal ranges, so it is important that you know the normal values.
You can see right away that the Hgb and Hct are lower than expected. This might make you think of a hemolytic process, or something affecting the RBCs. The reiculocyte count is also above the normal range (0.5% to 1.5%). So you might right away think about AIHA. However, the DAT is negative. The haptoglobin is also a little low. The normal range is 30 - 200 mg/dL. Haptoglobin is a protein that helps clear free hemoglobin from the circulation. It is decreased in a hemolytic process. Typically, if the haptoglobin is significantly decreased, and the reticulocytes are significantly increased also, then the hemolysis is happening intravascularly.
However if the haptoglobin is slightly decreased, and the reticulocyte count is only slightly increased, then the hemolysis is happening extravascularly. This is a general guideline for you - the values may var somewhat, and thre is not specific number that separates a “slight” increase from a “significant” increase.
SO, we have some hemolysis, although it is not due to antibody since the DAT is negative. So we rule out AIHA.
You can see that the coagulation tests are normal, but the platelet count is VERY low. The standard ranges are:
Platelet Count: 150,000 - 30,000 / uL
Bleeding Time: 3-7 minutes
PT: 10-12 seconds
APTT: 25-38 seconds
Thrombin Time: 9-35 seconds
Fibrinogen assay: 200-400 mg/dL
FDP/DDIMER: 0-11 and <500 ng/mL
So because the coagulation values are normal, we can rule out DIC.
So now we have it narrowed down to HUS and Thrombotic Thrombocytopenia Purpura.
HUS is a condition caused by a traid of pathologies - hemolytic anemia, kidney failure and thrombocytopenia. It primarily affects children rather than adults, although some adult cases have been reported. In addition, it generally is associated with infections, bloody diarrhea, and more significant symptoms. On the SBB exam, if you see a case of HUS, it will most likely be in a child. So while we have a significant thrombocytopenia, the hemolytic process not at a critical stage as we would expect in HUS.
The creatinine, which can help pinpoint a kidney problem is slightly decreased at 0.3 mg/dL in this case (normal range is 0.6 to 1.2 mg/dL). In HUS the creatinine would be higher than normal, indicating kidney failure.
The LDH is high, above the normal range of 100-190 U/L, and this can indicate tissue damage, but remember that LDH also exists inside RBCs, so any hemolytic process can also cause the LDH to increase. SO an LDH result all by itself is not something specific enough to help pinpoint what is happening. The LDH in conjunction with the normal creatinine helps us decide that this is not kidney failure. Also, in kidney failure she would likely be bloated, retaining fluids, and showing signs of tachycardia.
So now we can think about the platelet count, It is VERY low at 10,000/uL (normal is 150,000 to 300,000 /uL). Of the choices listed, TTP would result in a low platelet count, with some additional evidence of hemolysis.
In TTP, large vWF multimers are released into the periopheral circulation due to endothelial damage. The multimers increased platelet adhesion and clumping, so they are consumed and the platelet count drops. As a result, ischemia occurs, which is a blockage of the blood vessels resulting in lower oxygenation to tissues, due to the platelet clumping and large multimers. TTP also involves hemolytic process, which is differentiated from Immune Thrombocytopenia Purpura (ITP) because ITP does not typically involve hemolysis.
Which of the following does NOT cause DIC?
a. Obstetric complications
b. Hemophilia
c. Sepsis
d. Transfusion Reactions
b. Hemophilia
DIC is a condition in which small blood clots develop throughout the bloodstream, blocking small blood vessels. The increased clotting depletes the platelets and clotting factors needed to control bleeding, causing excessive bleeding.
Typically it is caused by some additional substance that enters the blood stream. So the conditions of obstetric complications, sepsis and transfusion reactions will all result in “something new” being produced that enters the blood stream. Hemophilia is a condition in which blood will not properly clot, but does into result in an “additional” substance to be produced that will cause DIC.
A 60 year old woman presents to her physician with complaints of unexplained bruising. She has no other complaints. Multiple ecchymoses are seen on her arms and legs. She has a history of uncomplicated cholecystectomy, hysterectomy, and vaginal deliveries (three). Her medical history is otherwise unremarkable, and she is not currently on any medications. The complete blood count is normal, as is the PT. The APTT is prolonged. The prolongation is not corrected by mixing with normal plasma. The most likely explanation for the patient’s findings is:
a. Type I vWD
b. Factor XII Inhibitor
c. Factor V Deficiency
d. Acquired Factor VIII Inhibitor
d. Acquired Factor VIII Inhibitor
In this case, the APTT is NOT corrected by mixing with normal human plasma. If there were a clotting factor deficiency, the addition of normal plasma would correct the APTT. Therefore, you should be thinking in terms of an inhibitor-which would still affect the APTT even if normal plasma were added, because the inhibitor would counteract the clotting factor in the sample.
So we are then left with a choice of two inhibitors Factor XII and Factor VIII. Factor XII deficiency does not result in abnormal coagulation, so the only choice left is Factor VIII deficiency.
A 64 year old female presents with a history of cough, fever, and right chest pain. After the appropriate workup, a diagnosis of deep right femoral vein thrombosis with pulmonary embolism is made. Symptoms resolve with bed rest and heparin anti-coagulation. Long-term anti-coagulation with warfarin is instituted and heparin is discontinued. Six months later, the patient is brought to the emergency room unresponsive. A computer tomography scan shows an intracerebral hemorrhage. Her INR is 9. The most effective immediate treatment is:
a. Prothrombin complex concentrate
b. Fresh frozen plasma
c. Intravenous (IV) vitamin K
d. Cryoprecipitated Antihemophiliac Factor (AHF)
a. Prothrombin complex concentrate
We are thinking here that warfarin inhibits vitamin K and so the cause of the bleeding is a lack of Vitamin K dependent factors. SO the question is, what is the most effective IMMEDIATE treatment? We want to control the bleed.
We first give the prothrombin complex to provide and immediate source of missing clotting factors. We would also start this patient on vitamin K, but that will not have an immediate affect. Intravenous Vitamin K will allow the patient to produce clotting factors that are Vitamin K dependent, but htis takes time to accomplish in sufficient amounts to have an effect on coagulation.
For the SBB exam, always choose the option that gives you the most effective treatment the fastest.
Which of the following statements concerning DIC is true?
a. Decreased levels of antithrombin III are associated with increased mortality.
b. Protein C and Protein S activity are increased.
c. The presence of thrombocytopenia makes the diagnosis of DIC highly likely
d. Factor VIII: levels are increased in most patients with DIC.
a. Decreased levels of antithrombin III are associated with increased mortality.
Anti-thrombin III inhibits the action of thrombin (which promotes clotting). If anti-thrombin III levels are low, then thrombin is allowed to act without control, and promotes clotting, further adding to the DIC problems. Low levels of the anti-thrombin III inhibitor are associated with higher levels of mortality.
Protein C and Protein S are often measured when diagnosing DIC, but their levels are usually decreased in DIC. The presence of thrombocytopenia is only one measure, and th efact that the patient is thrombocytopenic all by itself is not an indicator of DIC.
Factor VIII:C levels will be decreased in DIC.
A mild hemophiliac weighs 50 kg and has a Factor VIII activity of 10% and a hematocrit of 40%. He is scheduled to have minor surgery. How many units of Cryo would be required to raise the patient’s Factor VIII level to 50%?
a. 6
b. 9
c. 11
d. 14
c. 11
Formula to calculate this.
(Desired Factor VIII (units/ml) - Initial Factor VIII (units/ml) x plasma volume (ml) = units of Factor VIII required.
Units of Factor VIII required = #bags of cryo (Round up to the next whole number)
80
Plasma Volume = Blood Volume(ml) x (1.0 -HCT)
Blood Volume = weight(kg) x 70 ml/kg
50 kg x 70 ml/kg = 3500 ml Blood Volume
3500 ml x (1.0-0.40) = 2100 Plasma Volume
Desired Factor VIII - Initial Factor VIII = 50 - 10 = 40 units/ml
40 units/ml x 2100 (plasma volume) = 8400 units
8400/80 uints/bag = 10.5 bags of cryo, round up to 11.
Primary hemostasis is the complex activation of platelet adhesion, activation, and secretion, followed by platelet aggregation. These physiologic changes require multiple interactions with platelet surface proteins and the underlying sub-endothelial matrix.
Which of the following proteins allows for platelets to adhere to the underlying sub-endothelial matrix?
a. Platelet GP1b complex
b. Platelet GPVI protein
c. Platelet GP29
d. Platelet GP3C complex
a. Platelet GP1b complex
The platelet GP1b complex is composed of GP1b-GPV-GPIX and allows for platelet adhesion by binding to von Willebrand factor.
