Thrombotic Disorders — MCQs
All are predisposing factors of Deep Vein thrombosis, EXCEPT :
The anticoagulant activity of warfarin can be reduced by all of the following except.
Thrombotic event is seen in all of the following except:
Patient with clinical signs of DVT had tachycardia and history of bladder cancer. According to modified Well's scoring, the probability of pulmonary embolism would be :
Low molecular weight heparin mainly inhibits which factor?
The following condition is not associated with an Anti-phospholipid syndrome -
Anti-phospholipid syndrome (APS) is associated with all of the following except:
Thrombotic thrombocytopenic purpura is a syndrome characterized by which of the following?
Which of the following is commonly seen in Polycythemia Vera?
Etiology of disordered coagulation in antiphospholipid syndrome is
Thrombotic Disorders Indian Medical PG Practice Questions and MCQs
Question 1: All are predisposing factors of Deep Vein thrombosis, EXCEPT :
- A. Lower limb trauma
- B. Cushing's syndrome
- C. Hip surgery
- D. Subungual melanoma (Correct Answer)
Explanation: ***Subungual melanoma*** - This is a rare form of melanoma that develops under the nail, and while serious, it is **not a recognized predisposing factor for deep vein thrombosis (DVT)**. Its primary concerns are local invasion and metastasis. - Unlike conditions affecting blood clotting or endothelium, **subungual melanoma does not directly promote hypercoagulability, venous stasis, or endothelial damage** that contribute to DVT. *Lower limb trauma* - **Trauma to the lower limb** can cause **endothelial damage** to blood vessels and **venous stasis** due to immobility or swelling, both key components of **Virchow's triad** for DVT [1]. - **Fractures or severe soft tissue injuries** often necessitate immobilization and can lead to inflammation, further increasing the risk of clot formation [1]. *Cushing's syndrome* - **Cushing's syndrome** is associated with **hypercoagulability** due to increased levels of clotting factors, such as **factor VIII** and **fibrinogen**, and decreased fibrinolytic activity. - The **elevated cortisol levels** seen in Cushing's syndrome [2] can directly contribute to a prothrombotic state, significantly increasing DVT risk. *Hip surgery* - **Major orthopedic surgeries**, especially hip surgery [1], are well-known to cause significant **venous stasis** and **endothelial damage**. - **Post-operative immobility** and a generalized **inflammatory response** following surgery contribute to a high risk of DVT formation [1].
Question 2: The anticoagulant activity of warfarin can be reduced by all of the following except.
- A. Aspirin (Correct Answer)
- B. Rifampin
- C. Vitamin K
- D. Carbamazepine
Explanation: ***Aspirin*** - **Aspirin** does NOT reduce warfarin's anticoagulant activity; instead, it increases the risk of bleeding through a synergistic effect. - Aspirin inhibits platelet aggregation via **cyclooxygenase-1 (COX-1)** inhibition, preventing thromboxane A2 formation, which is a different mechanism from warfarin's inhibition of vitamin K-dependent clotting factors. - When combined with warfarin, aspirin **potentiates** the overall antithrombotic effect and increases bleeding risk. *Carbamazepine* - **Carbamazepine** is a potent inducer of hepatic cytochrome P450 enzymes (CYP2C9, CYP3A4). - By increasing warfarin metabolism, it **reduces** warfarin's plasma concentrations and decreases its anticoagulant effect. - Patients on this combination may require higher warfarin doses to maintain therapeutic INR. *Rifampin* - **Rifampin** is one of the most potent inducers of hepatic cytochrome P450 enzymes (CYP2C9, CYP3A4). - It significantly increases warfarin metabolism, leading to **reduced** plasma concentrations and diminished anticoagulant effect. - This interaction often necessitates substantial increases in warfarin dosage. *Vitamin K* - **Vitamin K** is the direct antagonist of warfarin's mechanism of action. - Warfarin inhibits vitamin K epoxide reductase, preventing the regeneration of active vitamin K needed for synthesis of clotting factors II, VII, IX, and X. - Administration of vitamin K **reverses** warfarin's anticoagulant effect by bypassing the inhibited enzyme and restoring clotting factor production.
Question 3: Thrombotic event is seen in all of the following except:
- A. Heparin induced thrombocytopenia
- B. Disseminated intravascular coagulation
- C. Idiopathic thrombocytopenic purpura (Correct Answer)
- D. Paroxysmal nocturnal hemoglobinuria
Explanation: ***Immune thrombocytopenic purpura*** - This condition primarily results in **thrombocytopenia**, leading to increased bleeding rather than thrombotic events [1][3]. - Patients typically present with **petechiae** and **purpura**, without the thrombotic complications seen in other conditions [1][3]. *Paroxysmal nocturnal hemoglobinuria* - Characterized by **hemolysis** and a risk of **thrombosis**, particularly in large veins. - Associated with **bone marrow** dysregulation, leading to increased blood viscosity and thrombotic events. *Heparin induced thrombocytopenia* - This condition leads to **thrombocytopenia** and paradoxically **increased thrombosis**, not bleeding. - It is caused by an immune response to heparin, resulting in the activation of platelets. *Disseminated intravascular coagulation* - Involves excessive clotting followed by a risk of bleeding due to **consumption of clotting factors** [1][2]. - Thrombotic events are common, with widespread small thrombi leading to organ dysfunction [2].
Question 4: Patient with clinical signs of DVT had tachycardia and history of bladder cancer. According to modified Well's scoring, the probability of pulmonary embolism would be :
- A. Low
- B. High
- C. Intermediate (Correct Answer)
- D. Intermediate
Explanation: **Intermediate** - Clinical signs of **DVT (3 points)**, **tachycardia (heart rate > 100 bpm, 1.5 points)**, and a history of **cancer (1 point)** sum up to 5.5 points, which falls within the range for an intermediate probability (2-6 points) on the modified Well's score for PE. - The modified Well's criteria assigns specific points for risk factors and clinical findings, guiding the diagnostic approach for pulmonary embolism [1]. *Low* - A low probability for PE according to the modified Well's score is indicated by a total score of **less than 2 points** [1]. - The patient's presentation accumulates significantly more points than this threshold due to multiple contributing factors. *High* - A high probability for PE according to the modified Well's score is indicated by a total score of **greater than 6 points** [1]. - The patient's score of 5.5 points does not meet this threshold, placing them in the intermediate category.
Question 5: Low molecular weight heparin mainly inhibits which factor?
- A. Factor VIIIa
- B. Factor Xa (Correct Answer)
- C. Factor XIIa
- D. Factor IIa
Explanation: ***Factor Xa*** - Low molecular weight heparin (LMWH) primarily exerts its anticoagulant effect by binding to **antithrombin III** and increasing its inhibitory activity against **Factor Xa**. - This selective inhibition of Factor Xa, rather than Factor IIa (thrombin), accounts for its more predictable anticoagulant response and lower risk of bleeding compared to unfractionated heparin. *Factor VIIIa* - **Factor VIIIa** is a cofactor in the intrinsic pathway, crucial for activating Factor X, but it is not directly inhibited by LMWH. - Its inhibition is more characteristic of **activated protein C**, not LMWH. *Factor XIIa* - **Factor XIIa** is involved in the initiation of the intrinsic coagulation pathway and the kallikrein-kinin system. - LMWH has no significant inhibitory effect on Factor XIIa. *Factor IIa* - While unfractionated heparin inhibits **Factor IIa (thrombin)** relatively equally to Factor Xa, LMWH has a much weaker inhibitory effect on Factor IIa due to its shorter chain length. - The anti-Factor IIa activity of LMWH is generally considered to be negligible compared to its **anti-Factor Xa activity**.
Question 6: The following condition is not associated with an Anti-phospholipid syndrome -
- A. Neurological manifestations
- B. Thrombocytosis (Correct Answer)
- C. Venous thrombosis
- D. Recurrent foetal loss
Explanation: ***Thrombocytosis*** - **Antiphospholipid syndrome (APS)** is characterized by a **prothrombotic state**, leading to **thrombocytopenia** (low platelet count), not thrombocytosis (elevated platelet count) [1]. - Elevated platelet counts are not part of the diagnostic criteria or typical clinical manifestations of APS. *Neurological manifestations* - **Neurological symptoms** are common in APS and can include **stroke**, **transient ischemic attacks (TIAs)**, **seizures**, and **cognitive dysfunction**. - These manifestations are due to the prothrombotic tendency affecting the cerebral vasculature. *Venous thrombosis* - **Venous thrombosis**, particularly **deep vein thrombosis (DVT)** and **pulmonary embolism (PE)**, is a hallmark feature of APS [2]. - The presence of antiphospholipid antibodies promotes clot formation in both venous and arterial systems. *Recurrent foetal loss* - **Recurrent foetal loss** (miscarriages or stillbirths) is a classic obstetric manifestation of APS [1]. - This occurs due to thrombosis in the placental circulation, impairing fetal development and viability [2].
Question 7: Anti-phospholipid syndrome (APS) is associated with all of the following except:
- A. Pancytopenia (Correct Answer)
- B. Venous thrombosis
- C. Pulmonary hypertension
- D. Recurrent abortions
Explanation: ***Pancytopenia*** - **Pancytopenia** is not directly associated with anti-phospholipid syndrome (APS); APS is primarily a prothrombotic disorder. - While other autoimmune conditions can cause pancytopenia, it is not a characteristic feature or complication of APS [1]. *Recurrent abortions* - This is a classic manifestation of APS, as **anti-phospholipid antibodies** interfere with placental development and function, leading to **pregnancy loss**. - Recurrent abortions, particularly in the second or third trimester, are a key diagnostic criterion for obstetric APS. *Venous thrombosis* - **Venous thrombosis**, especially deep vein thrombosis (DVT) and pulmonary embolism, is a hallmark feature of APS due to the **prothrombotic state** induced by the antibodies [1]. - This can occur in various vascular beds and is a primary clinical criterion for diagnosing APS. *Pulmonary hypertension* - Chronic or recurrent **pulmonary emboli** caused by APS can lead to **chronic thromboembolic pulmonary hypertension (CTEPH)**. - This is a significant long-term complication where the blood clots obstruct pulmonary arteries, increasing pressure in the pulmonary circulation.
Question 8: Thrombotic thrombocytopenic purpura is a syndrome characterized by which of the following?
- A. Thrombocytopenia, anemia, neurological abnormalities, progressive renal failure and fever (Correct Answer)
- B. Thrombocytopenia, anemia, neurological abnormalities, progressive hepatic failure and fever
- C. Thrombocytopenia, normal anemia, neurological abnormalities, progressive renal failure and fever
- D. Thrombocytopenia, anemia, no neurological abnormalities, progressive renal failure and fever
Explanation: ***Thrombocytopenia, anemia, neurological abnormalities, progressive renal failure and fever*** - Thrombotic thrombocytopenic purpura is characterized by **thrombocytopenia** and **microangiopathic hemolytic anemia**, along with neurological and renal complications [1][2]. - The presence of **fever** and other systemic symptoms is consistent with this **thrombotic microangiopathy** syndrome [1]. *Thrombocytosis, anemia, neurologic abnormalities, progressive renal failure and fever* - This option incorrectly lists **thrombocytosis** rather than **thrombocytopenia**, which is a hallmark of thrombotic thrombocytopenic purpura (TTP) [1]. - While it includes anemia, the absence of thrombocytopenia makes it inconsistent with TTP's classic presentation [2]. *Thrombocytopenia, anemia, neurologic abnormalities, progressive hepatic failure and fever* - Although it correctly states **thrombocytopenia** and **anemia**, it incorrectly identifies **progressive hepatic failure** instead of **renal failure**, which is a key feature of TTP [1]. - The presence of neurological abnormalities and fever does align with TTP; however, the hepatic failure aspect is misleading. *Thrombocytosis, anemia neurologic abnormalities, progressive renal failure and fever* - Again, this option incorrectly notes **thrombocytosis**, contradicting the characteristic finding of **thrombocytopenia** found in TTP [1]. - While other features align with TTP's clinical picture, the thrombocytosis excludes this option from being correct [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 947-948. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 667-668.
Question 9: Which of the following is commonly seen in Polycythemia Vera?
- A. Hyperuricemia
- B. Prone for acute leukemia
- C. Spontaneous severe infection
- D. Thrombosis (Correct Answer)
Explanation: ***Spontaneous severe infection*** - In Polycythemia Vera, there is usually an **increased red blood cell mass** leading to complications like thrombosis, rather than a predisposition to severe infections. - Severe infections are not a typical feature, as the condition usually maintains **functional immunity** despite hyperviscosity. *Thrombosis* - Individuals with Polycythemia Vera have increased blood viscosity that results in a higher risk of **thrombosis**, which is a common complication [1]. - Events like **deep vein thrombosis (DVT)** or **cerebral venous sinus thrombosis** are often observed due to altered hemodynamics. *Hyperuricemia* - Hyperuricemia occurs due to increased cell turnover and breakdown of red cells in Polycythemia Vera, leading to elevated **uric acid levels** [1]. - Patients may experience **gout attacks** as a consequence of this elevated uric acid [1]. *Prone for acute leukemia* - While there is an increased risk of transformation to myeloid neoplasms, the risk for **acute leukemia** is not directly attributed to Polycythemia Vera in most cases. - It is more related to myelofibrosis or secondary conditions developing over time rather than a direct association.
Question 10: Etiology of disordered coagulation in antiphospholipid syndrome is
- A. Hyper coagulation (Correct Answer)
- B. Slow blood flow
- C. Thrombocytosis
- D. Vitamin K malabsorption
Explanation: ***Hyper coagulation*** - Antiphospholipid Syndrome (APS) is characterized by the presence of **antiphospholipid antibodies** that promote a **prothrombotic state**, leading to both arterial and venous clotting. [1] - These antibodies interfere with regulatory proteins of coagulation (e.g., **protein C, protein S**) and interact with phospholipids on cell surfaces, causing increased platelet activation and endothelial dysfunction. *Slow blood flow* - While **venous stasis** can contribute to thrombosis, it is not the primary etiological factor for disordered coagulation in APS itself. - Slow blood flow is a component of **Virchow's triad**, which also includes endothelial injury and hypercoagulability, with the latter being the core issue in APS. [2] *Thrombocytosis* - **Thrombocytosis** (an abnormally high platelet count) can increase the risk of thrombosis, but it is not the direct or primary cause of disordered coagulation in APS. - APS specificially involves **antibody-mediated hypercoagulability**, not just an increased number of platelets. *Vitamin K malabsorption* - **Vitamin K malabsorption** can lead to a *deficiency* in vitamin K-dependent clotting factors, typically resulting in a **bleeding tendency** rather than hypercoagulation. - This condition is associated with **hypocoagulability**, which is the opposite of the disordered coagulation seen in APS.
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