Question 1

Which congenital deficiency(ies) is(are) suspected with a normal platelet count, an abnormal PT and APTT, and normal PFA-100 and thrombin time?
A) Factor VII
B) Factors X, V, II (prothrombin)
C) Factor VIII
D) Fibrinogen

Accepted Answer

A normal platelet count rules out any platelet-related disorders. Abnormal PT and APTT suggest a deficiency in factors responsible for the extrinsic and intrinsic pathways of coagulation. Normal PFA-100 and thrombin time rule out platelet function disorders and fibrinogen deficiency, respectively. The only deficiency that fits this pattern is in factors X, V, and II (prothrombin). Factor VII deficiency would result in an abnormal PT only, while factor VIII deficiency would result in an abnormal APTT only.

Question 2

F-VIII deficiency and F-IX deficiency are classified as what category of disorder?
A) Autosomal dominant
B) X-linked recessive
C) Autosomal recessive
D) X-linked dominant

Accepted Answer

F-VIII deficiency and F-IX deficiency are caused by mutations on the X chromosome and are inherited in an X-linked recessive manner.

Question 3

Deficiency of coagulation proteins is defined as a decrease in:
A) The concentration of the coagulation proteins
B) The concentration of the coagulation proteins and a subsequent decrease in the functionality of those proteins
C) The concentration of the coagulation proteins or impaired functionality of those proteins
D) Platelets that causes a decreased functionality of the coagulation proteins

Accepted Answer

Deficiency of coagulation proteins can result from a decrease in the concentration of the proteins or impaired functionality of those proteins. Both of these factors can contribute to a decrease in the effectiveness of the coagulation system, leading to bleeding disorders. Platelets are not directly involved in the synthesis or functionality of coagulation proteins, so option D is incorrect. Option B is partially correct but does not include the possibility of a deficiency in functionality alone, without a decrease in concentration.

Question 4

Which of the following clinical symptoms correlates with a severe form of hemophilia A or B?
A) Bleeding at circumcision with a factor level of 1-5 U/dL
B) Excessive bleeding after surgery or trauma with a factor level of 6-30 U/dL
C) Frequent spontaneous hemarthroses
D) Infrequent spontaneous joint and tissue bleeds

Accepted Answer

Frequent spontaneous hemarthroses (joint bleeding) is a key clinical symptom of severe hemophilia A or B. Infrequent spontaneous joint and tissue bleeds are more characteristic of mild or moderate forms of hemophilia. Bleeding at circumcision with a factor level of 1-5 U/dL and excessive bleeding after surgery or trauma with a factor level of 6-30 U/dL can occur in all forms of hemophilia, but are not necessarily indicative of a severe form.

Question 5

What is the inheritance pattern of hemophilia A?
A) Autosomal dominant
B) Autosomal recessive
C) Sex-linked
D) None of these

Accepted Answer

Hemophilia A is an X-linked recessive disorder, meaning it is caused by a gene on the X chromosome and primarily affects males. Females can also be carriers of the gene and pass it on to their children.

Question 6

One of the most common hemostatic abnormalities found in "sick" infants is:
A) DIC
B) Factor XIII deficiency
C) Hemophilia
D) Vitamin K deficiency

Accepted Answer

Vitamin K deficiency is the most common hemostatic abnormality found in "sick" infants.

Question 7

What term describes hereditary or acquired disorders that relate to the absence of a coagulation protein or to a protein that is present in the plasma but is functionally defective?
A) Circulating anticoagulant
B) Lupus anticoagulant
C) Deficiency
D) Dysfunctional

Accepted Answer

Deficiency disorders refer to a lack of coagulation proteins or to a protein that is present but does not function properly, leading to abnormal bleeding or clotting. Circulating anticoagulants and Lupus anticoagulants refer specifically to substances that inhibit coagulation, rather than a deficiency of coagulation proteins. Dysfunctional disorders may refer to a variety of conditions, not necessarily related to coagulation.

Question 8

George Jones is admitted to the hospital with abdominal pain. Upon physical examination, the attending physician notices a yellow ring around his green eyes. George has a significant swelling in his abdomen and has been suffering from swollen joints for the last month. The physician runs a battery of labs. The results follow:  Based on this information, from what is George most likely suffering?
A) Liver disease
B) Vitamin K deficiency
C) Disseminated intravascular coagulation
D) Massive cerebral hemorrhage

Accepted Answer

George is most likely suffering from liver disease, as indicated by the yellow ring around his green eyes (a sign of jaundice) and the significant swelling in his abdomen. The abnormal lab values also suggest liver dysfunction, specifically increased levels of bilirubin and decreased levels of albumin.

Question 9

A patient might be suffering from a coagulopathy. Which of the following physical manifestations would suggest a primary hemostatic pathway problem?
A) Hematomas
B) Petechiae
C) Joint and muscle bleeding
D) Ecchymoses

Accepted Answer

Petechiae are small, pinpoint, red or purple spots caused by bleeding into the skin, and are a common finding in primary hemostatic pathway problems. Hematomas, joint and muscle bleeding, and ecchymoses are more indicative of a secondary hemostatic pathway problem.

Question 10

Interpret the following results: PT: 11.8 sec (RR: 11.2-13.8 sec)
INR: 1.07
APTT: 57 sec (RR: 23-32 sec)
Closure time: increased
Ristocetin aggregation: decreased aggregation
Based on this information, what is the most likely disorder?
A) Hemophilia A
B) Bernard-Soulier syndrome
C) DIC
D) von Willebrand's disease

Accepted Answer

- PT (prothrombin time) is within normal range, which rules out factors associated with hemophilia A or DIC.
- APTT (activated partial thromboplastin time) is significantly prolonged beyond the reference range, which suggests a clotting factor deficiency or inhibition. However, the INR (international normalized ratio) is normal, which rules out vitamin K deficiency or warfarin therapy.
- The closure time is prolonged, which indicates impaired platelet function.
- Ristocetin aggregation test is decreased, indicating a defect in von Willebrand factor. 
All of these findings are consistent with von Willebrand's disease.

Question 11

What is the most probable diagnosis?
A) von Willebrand's disease
B) DIC
C) Hemophilia possibly
D) Lupus anticoagulant

Accepted Answer

Hemophilia is characterized by a deficiency in clotting factors (Factor VIII in Hemophilia A, Factor IX in Hemophilia B) leading to prolonged bleeding. The question's phrasing suggests a bleeding disorder, and among the options, Hemophilia is the most directly associated with such symptoms.

Question 12

Screening tests for the evaluation of VWD include the platelet count, APTT, PT, bleeding time, and/or PFA-100. Which of the following results would be evident in most cases of VWD?
A) Low platelet count
B) Decreased ristocetin platelet aggregation
C) Normal ristocetin platelet aggregation
D) Normal Ag assay

Accepted Answer

Decreased ristocetin platelet aggregation is the most common abnormal finding in VWD, as VWF plays a crucial role in platelet adhesion and aggregation. The other tests listed may be abnormal in some cases of VWD, but not in all cases. Low platelet counts may be seen in severe cases of VWD, but not necessarily in all cases. A normal Ag assay result would not be indicative of VWD.

Question 13

A 5-year-old boy has his blood drawn for platelet aggregation studies. Ristocetin aggregation (RIPA) comes back abnormal with all other agonists displaying normal aggregation. VWF antigen is within normal limits. What is the most likely reason for this discrepancy?
A) The VWF antigen test was performed incorrectly and should be repeated.
B) The patient might be suffering from a qualitative platelet defect disorder.
C) The RIPA exam was performed incorrectly and should be repeated.
D) Multimer analysis should be performed to confirm these findings.

Accepted Answer

Abnormal RIPA with normal VWF antigen levels suggest a qualitative defect of platelet function. Multimer analysis may be done to confirm the diagnosis but a qualitative platelet disorder remains the most likely explanation. The VWF antigen test is not likely to be the issue as it was within normal limits. RIPA exam can be done again but is unlikely to change the result.

Question 14

A known hemophiliac has developed an inhibitor. The physician in charge of his care wants to know how much inhibitor is present to properly treat him. What two lab tests would be ordered to assess this?
A) APTT; factor assay
B) Factor VIII: C level; Bethesda titer
C) VWF antigen; Bethesda titer
D) Type and screen; factor assay

Accepted Answer

The two lab tests that would be ordered to assess the inhibitor in a hemophiliac are Factor VIII:C level and Bethesda titer. Factor VIII:C level will determine the amount of clotting factor VIII in the patient's blood, while Bethesda titer will measure the strength of the inhibitor in the patient's blood.

Question 15

Predict results that will confirm the patient's diagnosis.
A) Abnormal aggregation with Ristocetin
B) An increased D-dimer
C) Decreased activity of either factors VIII or IX
D) The presence of an inhibitor pattern in a mixing study

Accepted Answer

Decreased activity of either factors VIII or IX is indicative of hemophilia A or B, respectively, which are common diagnoses related to clotting factor deficiencies.

Question 16

What should be the next course of action in investigating these results?
A) Repeat the aggregation studies
B) Start the patient on Coumadin
C) Order factor assays of the intrinsic pathway
D) Order factor assays of the intrinsic, extrinsic, and common pathways

Accepted Answer

The abnormal PTT results suggest a defect in the intrinsic pathway, so factor assays of the intrinsic pathway should be ordered to identify the specific factor(s) that are deficient or dysfunctional. Repeat aggregation studies or starting the patient on Coumadin are not appropriate next steps in investigating these results. Ordering factor assays of the extrinsic and common pathways may be considered later depending on the results of the intrinsic pathway assays.

Question 17

Hemophilia A is caused by a deficiency in which of the following proteins?
A) von Willebrand's factor
B) Factor VIII
C) Factor IX
D) Glycoprotein IIb/IIIa

Accepted Answer

Hemophilia A is caused by a deficiency in Factor VIII, a protein that plays an important role in blood clotting. Deficiency in Factor VIII leads to impaired clotting and increased bleeding tendencies.

Question 18

A physician has confirmed von Willebrand's disease in a patient. Further testing is needed to determine which subtype the patient has. Multimer analysis is performed and comes back normal. What is the most probable explanation for this?
A) The patient is not suffering from von Willebrand's disease.
B) The patient is suffering from type I VWD.
C) The patient has BSS.
D) The wrong patient was drawn.

Accepted Answer

Type I von Willebrand's disease (VWD) is characterized by a quantitative deficiency of von Willebrand factor (VWF), which can result in a normal multimer analysis. This subtype is the most common form of VWD and is distinguished by lower levels of VWF, but the structure of the VWF multimers remains normal.

Question 19

A 34-year-old woman has just given birth to a healthy baby boy. After the delivery of the baby, the physician proceeds to deliver the placenta. After it has been extracted from the mother's uterus, the resident examines it and notes that it appears incomplete. They try to deliver the remainder but are unsuccessful. A few moments later, the mother loses consciousness, and is bleeding profusely from her uterus. Blood is collected, and the results follow. PT: 17 sec (RR: 11.3-12.8 sec)
INR: 3.02
APTT: 67 sec (RR: 23-32 sec)
D-dimer: 540 ng/mL (RR: <400 ng/mL)
Fibrinogen: 82 mg/dL (RR: 200-400 mg/dL)
Factor V assay: 12%
Based on this information, from what is the most probable diagnosis?
A) Hemophilia A
B) von Willebrand's disease
C) Placenta previa
D) DIC

Accepted Answer

The abnormal coagulation studies, including prolonged PT, APTT, elevated INR, decreased fibrinogen and factor V assay, and elevated D-dimer all suggest disseminated intravascular coagulation (DIC). The incomplete placental delivery and subsequent postpartum hemorrhage are also consistent with DIC, as DIC can occur as a result of severe obstetric complications such as placenta previa, abruption, and retained products of conception. Hemophilia A and von Willebrand's disease would lead to prolonged APTT but would not cause the abnormalities seen in other coagulation studies, including PT, INR, and factor assays.

Question 20

Which of the following is used in the identification of a secondary hemostatic pathway anomaly?
A) Bleeding time
B) ACE activity
C) Platelet aggregation studies
D) Factor assays

Accepted Answer

Factor assays are used in the identification of a secondary hemostatic pathway anomaly because they measure the levels and activity of specific clotting factors involved in the coagulation cascade. This can help identify deficiencies or defects in certain factors, such as factor VIII in hemophilia A or factor IX in hemophilia B. Bleeding time, ACE activity, and platelet aggregation studies are more useful for identifying primary hemostatic pathway abnormalities related to platelet function or vascular integrity.

Quiz 34: Disorders of Secondary Hemostasis

Which congenital deficiency(ies) is(are) suspected with a normal platelet count, an abnormal PT and APTT, and normal PFA-100 and thrombin time?

F-VIII deficiency and F-IX deficiency are classified as what category of disorder?

Deficiency of coagulation proteins is defined as a decrease in:

Which of the following clinical symptoms correlates with a severe form of hemophilia A or B?

What is the inheritance pattern of hemophilia A?

One of the most common hemostatic abnormalities found in "sick" infants is:

What term describes hereditary or acquired disorders that relate to the absence of a coagulation protein or to a protein that is present in the plasma but is functionally defective?

A patient might be suffering from a coagulopathy. Which of the following physical manifestations would suggest a primary hemostatic pathway problem?

Interpret the following results: PT: 11.8 sec (RR: 11.2-13.8 sec) INR: 1.07 APTT: 57 sec (RR: 23-32 sec) Closure time: increased Ristocetin aggregation: decreased aggregation Based on this information, what is the most likely disorder?

What is the most probable diagnosis?

Screening tests for the evaluation of VWD include the platelet count, APTT, PT, bleeding time, and/or PFA-100. Which of the following results would be evident in most cases of VWD?

A 5-year-old boy has his blood drawn for platelet aggregation studies. Ristocetin aggregation (RIPA) comes back abnormal with all other agonists displaying normal aggregation. VWF antigen is within normal limits. What is the most likely reason for this discrepancy?

A known hemophiliac has developed an inhibitor. The physician in charge of his care wants to know how much inhibitor is present to properly treat him. What two lab tests would be ordered to assess this?

Predict results that will confirm the patient's diagnosis.

What should be the next course of action in investigating these results?

Hemophilia A is caused by a deficiency in which of the following proteins?

A physician has confirmed von Willebrand's disease in a patient. Further testing is needed to determine which subtype the patient has. Multimer analysis is performed and comes back normal. What is the most probable explanation for this?

Which of the following is used in the identification of a secondary hemostatic pathway anomaly?