A 6-year-old boy has a swollen, painful knee after a minor fall; his maternal uncle bleeds easily. Platelets 280,000/µL, bleeding time normal, PT 13 s (control 12 s), APTT 72 s (control 32 s). A 1:1 mix with normal plasma corrects the APTT. The next test should be:

Factor VIII and factor IX assays

Hematology: coagulation and hemostasis

22 Kerala PSC Lab Technician Gr II practice questions on Hematology: coagulation and hemostasis, part of Pathology. The first 22 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
Which coagulation factor is NOT vitamin K dependent?
1. AFactor X
2. BFactor VIII
3. CFactor II
4. DFactor VII
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Answer: B · Factor VIII
Factors II, VII, IX and X, and proteins C and S, need vitamin K for the gamma-carboxylation of glutamic acid residues, which lets them bind calcium and phospholipid. Factor VIII is made mainly by endothelial cells and does not depend on vitamin K. Warfarin blocks vitamin K recycling and lowers the dependent factors, which is why it is monitored with the PT/INR. Factor VIII is low in hemophilia A, not in vitamin K deficiency.
- A: Factor X is vitamin K dependent.
- C: Factor II (prothrombin) is vitamin K dependent.
- D: Factor VII is vitamin K dependent and has the shortest half-life of the group.
Question 2 · Medium
A woman with petechiae has a bleeding time of 12 minutes (Duke method; normal 1-5 minutes) and a normal clotting time. The most likely cause is:
1. AHemophilia A
2. BFactor IX deficiency
3. CThrombocytopenia
4. DVitamin K deficiency
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Answer: C · Thrombocytopenia
Bleeding time tests the platelet plug: platelet number, platelet function and the vessel wall. A long bleeding time with a normal clotting time and petechiae points to a platelet problem such as thrombocytopenia (or von Willebrand disease or a platelet function defect). Clotting factor deficiencies prolong the clotting time but leave the bleeding time normal. A platelet count and peripheral smear are the next tests.
- A: Hemophilia A prolongs the clotting time; the bleeding time is normal.
- B: Factor IX deficiency (Christmas disease) affects clotting, not the platelet plug.
- D: Vitamin K deficiency lowers factors II, VII, IX and X and does not prolong the bleeding time.
Question 3 · Easy
The INR is used to report the prothrombin time of patients on which drug?
1. AClopidogrel
2. BAspirin
3. CWarfarin
4. DHeparin
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Answer: C · Warfarin
INR = (patient PT ÷ mean normal PT) raised to the power of the ISI of the thromboplastin. It corrects for differences between reagents, so warfarin patients get comparable results in any laboratory. A target INR of 2.0-3.0 suits most indications. Unfractionated heparin is monitored with the APTT, and antiplatelet drugs are not monitored with the PT.
- A: Clopidogrel is an antiplatelet drug and does not prolong the PT.
- B: Aspirin affects platelet function, not the PT.
- D: Unfractionated heparin is monitored with the APTT or an anti-Xa assay.
Question 4 · Hard
A 6-year-old boy has a swollen, painful knee after a minor fall; his maternal uncle bleeds easily. Platelets 280,000/µL, bleeding time normal, PT 13 s (control 12 s), APTT 72 s (control 32 s). A 1:1 mix with normal plasma corrects the APTT. The next test should be:
1. AFactor VIII and factor IX assays
2. BRepeat PT with fresh reagent
3. CPlatelet aggregation studies
4. DLupus anticoagulant screen
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Answer: A · Factor VIII and factor IX assays
Joint bleeding in a boy with an affected maternal uncle suggests an X-linked factor deficiency. The isolated long APTT, with a normal PT, platelet count and bleeding time, points to the intrinsic pathway, and correction on mixing shows a deficiency rather than an inhibitor. Hemophilia A (factor VIII) and hemophilia B (factor IX) look identical in screening tests, so both factor assays are needed. The result decides which factor concentrate he receives.
- B: The PT is normal, so repeating it would not explain the long APTT.
- C: Platelet aggregation tests are for platelet disorders; the platelets and bleeding time are normal here.
- D: A lupus anticoagulant would not correct on mixing and rarely causes bleeding.
Question 5 · Medium
Which factor deficiency prolongs the APTT but leaves the PT normal?
1. AFactor X
2. BFactor VII
3. CFactor IX
4. DFibrinogen
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Answer: C · Factor IX
The APTT tests the intrinsic and common pathways (factors XII, XI, IX, VIII, X, V, II and fibrinogen), while the PT tests the extrinsic and common pathways (VII, X, V, II and fibrinogen). A factor found only in the intrinsic pathway, such as IX, prolongs the APTT alone. Deficiency of a common-pathway factor prolongs both tests, and factor VII deficiency prolongs only the PT. A mixing study and factor assays then identify the exact factor.
- A: Factor X is in the common pathway, so both the PT and APTT are prolonged.
- B: Factor VII deficiency prolongs the PT and leaves the APTT normal.
- D: Low fibrinogen prolongs both the PT and the APTT.
Question 6 · Medium
Why must a citrate tube for PT and APTT be filled exactly to the mark?
1. AExcess citrate in an underfilled tube shortens the times
2. BExcess citrate in an underfilled tube prolongs the times
3. CA full tube is needed to keep platelets from clumping
4. DAir in an underfilled tube activates the clotting factors
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Question 7 · Easy
Which coagulation factor cross-links fibrin to make the clot stable?
1. AFactor XII
2. BFactor VII
3. CFactor X
4. DFactor XIII
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Question 8 · Easy
Christmas factor is another name for:
1. AFactor IX
2. BFactor X
3. CFactor VIII
4. DFactor XI
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Question 9 · Medium
A 24-year-old woman has heavy periods and bled for a long time after a dental extraction. Platelets 260,000/µL, bleeding time (Ivy) 11 minutes (normal 2-7), PT normal, APTT mildly prolonged. The most likely diagnosis is:
1. AHemophilia A
2. BVon Willebrand disease
3. CVitamin K deficiency
4. DImmune thrombocytopenia
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Question 10 · Hard
A 30-year-old woman with placental abruption starts oozing from drip sites. Platelets 48,000/µL, PT 24 s (control 13 s), APTT 68 s (control 32 s), fibrinogen 90 mg/dL (reference 200-400), D-dimer markedly raised; the smear shows fragmented red cells. The most likely diagnosis is:
1. AVitamin K deficiency
2. BHemophilia A
3. CImmune thrombocytopenic purpura
4. DDisseminated intravascular coagulation
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Question 11 · Hard
A 4-day-old breastfed baby, born at home without any injections, bleeds from the umbilical stump and passes blood in the stool. Platelets 2.4 lakhs/µL, PT 38 s (control 13 s), APTT 70 s (control 32 s), fibrinogen normal. The most likely diagnosis is:
1. AHemophilia A
2. BVitamin K deficiency bleeding of the newborn
3. CNeonatal immune thrombocytopenia
4. DDisseminated intravascular coagulation
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Question 12 · Easy
In the one-stage prothrombin time (Quick's method), citrated plasma is clotted by adding:
1. AProtamine sulphate
2. BKaolin, cephalin and calcium chloride
3. CThrombin solution
4. DThromboplastin and calcium chloride
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Question 13 · Easy
A raised plasma D-dimer shows the breakdown of:
1. AFibrinogen by thrombin
2. BProthrombin by activated factor X
3. CPlatelets by antibodies
4. DCross-linked fibrin by plasmin
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Question 14 · Easy
Which laboratory test is used to monitor treatment with unfractionated heparin?
1. APlatelet count
2. BProthrombin time
3. CBleeding time
4. DAPTT
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Question 15 · Hard
Calculate the INR for a man taking warfarin for atrial fibrillation: his PT 39 s, mean normal PT 13 s, thromboplastin ISI 1.2.
1. A1.7
2. B3.6
3. C3.7
4. D3.0
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Question 16 · Medium
A thrombin time is prolonged, but the plasma fibrinogen level is normal. The most common cause is:
1. AFactor VIII deficiency
2. BFactor VII deficiency
3. CLow platelet count
4. DHeparin in the sample
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Question 17 · Medium
A 7-year-old boy has bled easily since infancy. Platelet count 2.8 lakhs/µL, bleeding time prolonged, PT and APTT normal, and clot retraction is poor. The most likely diagnosis is:
1. AGlanzmann thrombasthenia
2. BHemophilia A
3. CImmune thrombocytopenia
4. DVitamin K deficiency
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Question 18 · Medium
Which result pattern is expected in isolated factor VII deficiency?
1. APT and APTT both prolonged
2. BPT and APTT both normal
3. CPT normal, APTT prolonged
4. DPT prolonged, APTT normal
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Question 19 · Medium
All of the following prolong the bleeding time EXCEPT:
1. Avon Willebrand disease
2. BImmune thrombocytopenia
3. CHemophilia A
4. DAspirin therapy
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Question 20 · Easy
The tourniquet (Hess) test is a bedside test of:
1. AFactor VIII level
2. BCapillary fragility
3. CFibrinolytic activity
4. DPlatelet aggregation
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Question 21 · Medium
How does aspirin prolong the bleeding time for about a week after a single dose?
1. AIt blocks vitamin K epoxide reductase in the liver
2. BIt lowers the plasma factor VIII level
3. CIt irreversibly inhibits platelet cyclo-oxygenase
4. DIt destroys platelets in the spleen
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Question 22 · Easy
Coagulation factor IV is:
1. ATissue factor
2. BCalcium
3. CFibrinogen
4. DProthrombin
Answer and explanation in LearnFree account

Hematology: coagulation and hemostasis

Which coagulation factor is NOT vitamin K dependent?

A woman with petechiae has a bleeding time of 12 minutes (Duke method; normal 1-5 minutes) and a normal clotting time. The most likely cause is:

The INR is used to report the prothrombin time of patients on which drug?

A 6-year-old boy has a swollen, painful knee after a minor fall; his maternal uncle bleeds easily. Platelets 280,000/µL, bleeding time normal, PT 13 s (control 12 s), APTT 72 s (control 32 s). A 1:1 mix with normal plasma corrects the APTT. The next test should be:

Which factor deficiency prolongs the APTT but leaves the PT normal?

Why must a citrate tube for PT and APTT be filled exactly to the mark?

Which coagulation factor cross-links fibrin to make the clot stable?

Christmas factor is another name for:

A 24-year-old woman has heavy periods and bled for a long time after a dental extraction. Platelets 260,000/µL, bleeding time (Ivy) 11 minutes (normal 2-7), PT normal, APTT mildly prolonged. The most likely diagnosis is:

A 30-year-old woman with placental abruption starts oozing from drip sites. Platelets 48,000/µL, PT 24 s (control 13 s), APTT 68 s (control 32 s), fibrinogen 90 mg/dL (reference 200-400), D-dimer markedly raised; the smear shows fragmented red cells. The most likely diagnosis is:

A 4-day-old breastfed baby, born at home without any injections, bleeds from the umbilical stump and passes blood in the stool. Platelets 2.4 lakhs/µL, PT 38 s (control 13 s), APTT 70 s (control 32 s), fibrinogen normal. The most likely diagnosis is:

In the one-stage prothrombin time (Quick's method), citrated plasma is clotted by adding:

A raised plasma D-dimer shows the breakdown of:

Which laboratory test is used to monitor treatment with unfractionated heparin?

Calculate the INR for a man taking warfarin for atrial fibrillation: his PT 39 s, mean normal PT 13 s, thromboplastin ISI 1.2.

A thrombin time is prolonged, but the plasma fibrinogen level is normal. The most common cause is:

A 7-year-old boy has bled easily since infancy. Platelet count 2.8 lakhs/µL, bleeding time prolonged, PT and APTT normal, and clot retraction is poor. The most likely diagnosis is:

Which result pattern is expected in isolated factor VII deficiency?

All of the following prolong the bleeding time EXCEPT:

The tourniquet (Hess) test is a bedside test of:

How does aspirin prolong the bleeding time for about a week after a single dose?

Coagulation factor IV is: