Question 1

A 53-year-old woman arrives at the hospital with bleeding into the back of the throat and has a coagulation screen performed. She has no history of abnormal bleeding before this despite major stress to hemostasis in the past: she was in a major automobile accident at age 37 and has had impacted wisdom teeth extracted. Her coagulation results follow:

Which of the following is the most likely cause for her bleeding?

Accepted Answer

A)   Factor XII deficiency
B)   Factor IX deficiency
C)   Factor VIII deficiency
D)   Factor VIII inhibitor D

Question 2

How often must the partial thromboplastin time (PTT) reference interval be determined?

Accepted Answer

A)   Only when both the normal and abnormal controls are outside their acceptable limits
B)   At least every 6 months
C)   With each new lot of reagent
D)   Only when the normal control is outside its acceptable limits C

Question 3

A patient's platelet count drops 4 days after being placed on heparin. Select the correct interpretation.

Accepted Answer

A)   The patient has heparin-induced thrombocytopenia.
B)   The patient has benign, limited thrombocytopenia related to heparin.
C)   A bleeding time should be performed to evaluate qualitative platelet disorders.
D)   An immunoassay for heparin-dependent anti-platelet factor 4 (PF4)  should be performed to distinguish heparin-induced thrombocytopenia from benign, limited thrombocytopenia related to heparin. D

Question 4

A platelet aggregation study shows diminished response to all agonists except for a small response to arachidonic acid and full response to ristocetin. Which condition is most likely?

Accepted Answer

A)   Glanzmann thrombasthenia
B)   Aspirin use
C)   VWD
D)   Platelet release defect

Question 5

Patients with which of the following would have a normal PT?

Accepted Answer

A)   Liver disease
B)   Disseminated intravascular coagulation (DI
C)  
C)   Factor VII deficiency
D)   Factor IX deficiency

Question 6

Which of the following is acceptable practice regarding collection of blood when using a syringe and winged needle set?

Accepted Answer

A)   Blood can be transferred to evacuated tubes once the phlebotomist returns to the laboratory.
B)   Evacuated tubes must be placed in a rack when filling.
C)   The first 20 mL collected must be discarded.
D)   The evacuated tube stopper is removed, and blood is squirted into the tube using a 24-gauge needle.

Question 7

A patient sample has normal platelet aggregation patterns for all agonists except that no reaction occurs with ristocetin. Ristocetin agglutination is not corrected with exogenous VWF. What condition is most likely?

Accepted Answer

A)   VWD
B)   Storage pool disorder
C)   Bernard-Soulier syndrome
D)   Aspirin use

Question 8

A patient is stabilized on warfarin with an international normalized ratio (INR) of 2.7. He develops pneumonia and is admitted to the hospital. His appetite is depressed and he is placed on broad-spectrum antibiotic agents. At 1 week after the admission, his INR is 5.0. What is the most likely interpretation?

Accepted Answer

A)   The patient should be given more warfarin.
B)   A PTT should be performed to rule out heparin administration.
C)   A new sample should be collected to rule out a clotted specimen.
D)   Vitamin K is reduced, increasing the effects of warfarin.

Question 9

Which of the following is an acceptable sample for a prothrombin time (PT) test?

Accepted Answer

A)   One that was collected 22 hours before testing and stored at room temperature
B)   One with a very small clot that was easily removed
C)   3.2% Sodium citrate blood sample immediately collected following a serum separator tube
D)   Blood anticoagulated with heparin and brought to the laboratory within 1 hour

Question 10

Standard curves are necessary for which coagulation procedures?

Accepted Answer

A)   Thrombin time
B)   Specific factor assays
C)   Fibrinogen assay
D)   Both specific factor assays and fibrinogen assay

Question 11

The urea solubility test evaluates factor:

Accepted Answer

A)   I
B)   V
C)   X
D)   XIII

Question 12

A patient admitted to the hospital with thrombosis is given the standard heparin dosage. Twenty-four hours after the heparin is started, the PTT is 38 seconds (reference range, 25 to 37 seconds). Both normal and abnormal controls are within their limits. Which of the following is most likely?

Accepted Answer

A)   Laboratory error
B)   Patient has low antithrombin
C)   Heparin-induced thrombocytopenia
D)   Patient should be switched to low-molecular-weight heparin (LMWH)

Question 13

Which of the following will cause spuriously prolonged clot-based coagulation tests?

Accepted Answer

A)   An evacuated 3.2% sodium citrate tube filled to 50% capacity
B)   An evacuated 3.2% sodium citrate tube filled to 90% capacity
C)   Prolonged tourniquet application
D)   Plasma collected from a traumatic tap

Question 14

A patient is positive for fibrin degradation products and negative for D dimers. Which condition is most likely?

Accepted Answer

A)   Systemic fibrinolysis
B)   DIC
C)   Hypofibrinogenemia
D)   Deep vein thrombosis (DVT)

Question 15

Which of the following conditions is associated with an elevated fibrinogen?

Accepted Answer

A)   Acute DIC
B)   Chronic inflammation
C)   Severe liver disease
D)   Increased plasmin levels

Question 16

Which of the following conditions would have a normal PTT?

Accepted Answer

A)   Lupus anticoagulant
B)   Fibrinogen of 50 mg/dL
C)   Factor VII deficiency
D)   Heparin therapy

Question 17

A prolonged PTT is corrected when mixed with normal plasma and tested immediately and after a 2-hour incubation. Which test (or tests) should be performed next?

Accepted Answer

A)   Bethesda titer
B)   High phospholipid PTT
C)   Anti-Xa assay
D)   Factor VIII and IX assays

Question 18

Which of the following is necessary for normal platelet aggregation?

Accepted Answer

A)   Ristocetin
B)   von Willebrand factor (VWF) 
C)   Epinephrine
D)   Fibrinogen

Question 19

How often must controls be run for the PT and PTT?

Accepted Answer

A)   With each patient sample
B)   At least once per 8-hour shift
C)   At least once per 24 hours
D)   With each batch of 10

Question 20

A patient has a hematocrit of 65%. Which of the following is true related to coagulation testing?

Accepted Answer

A)   Hematocrit does not affect coagulation testing.
B)   Tube must be recollected with heparin as the anticoagulant.
C)   Tube must be recollected using 0.34 mL of sodium citrate to 4.5 mL of blood.
D)   Tube must be recollected using 0.62 mL of sodium citrate to 4.5 mL of blood.

Exam 45: Laboratory Evaluation of Hemostasis