Haemostasis MCQs: Master Coagulation & Bleeding Control

Question 1

What is haemostasis?

Accepted Answer

Process by which bleeding stops — Haemostasis is the physiological sequence that arrests bleeding through vasoconstriction, platelet plug, and coagulation.

Question 2

Which vitamin is essential for synthesis of coagulation factors?

Accepted Answer

Vitamin K — Vitamin K is required for gamma-carboxylation of factors II, VII, IX, and X — making them functional.

Question 3

Fibrinogen is also known as?

Accepted Answer

Factor I — Fibrinogen = Factor I; thrombin cleaves it to form fibrin, the structural component of a clot.

Question 4

Which is NOT one of the four major physiologic events of haemostasis?

Accepted Answer

Fibrinolysis — The four events are: vascular spasm, platelet plug, coagulation, and clot retraction/repair. Fibrinolysis is clot dissolution — a separate process.

Question 5

First step in haemostasis when a blood vessel is injured?

Accepted Answer

Vascular spasm — The immediate response to vascular injury is smooth muscle contraction (vasoconstriction) to reduce blood flow.

Question 6

Which mineral is essential for the clotting process?

Accepted Answer

Calcium — Calcium (Factor IV) is required as a cofactor at multiple steps in the coagulation cascade.

Question 7

Deficiency of Factor VIII leads to?

Accepted Answer

Hemophilia A — Factor VIII deficiency = Hemophilia A; Factor IX deficiency = Hemophilia B (Christmas disease).

Question 8

Which factor is known as the "Christmas factor"?

Accepted Answer

Factor IX — Named after Stephen Christmas, the first patient diagnosed with Factor IX deficiency (Hemophilia B).

Question 9

Which of the following is a natural anticoagulant?

Accepted Answer

Heparin — Heparin (endogenous, from mast cells) potentiates antithrombin III to inhibit thrombin and Factor Xa.

Question 10

Main function of von Willebrand factor?

Accepted Answer

Binds platelets to collagen — vWF acts as a bridge between exposed subendothelial collagen and platelet GPIb receptors, initiating primary haemostasis.

Question 11

Which test screens for platelet and blood vessel function?

Accepted Answer

Bleeding time — Bleeding time assesses primary haemostasis (platelet plug formation and vascular response), not the coagulation cascade.

Question 12

Which pathway does warfarin primarily affect?

Accepted Answer

Extrinsic — Warfarin most noticeably affects Factor VII (shortest half-life), exclusive to the extrinsic pathway — hence PT/INR monitors it.

Question 13

End product of the coagulation cascade?

Accepted Answer

Insoluble fibrin clot — Thrombin cleaves fibrinogen → fibrin monomers → polymerize → cross-linked by Factor XIIIa into a stable insoluble clot.

Question 14

Which factor stabilizes the fibrin clot by cross-linking fibrin?

Accepted Answer

Factor XIIIa — Thrombin activates Factor XIII → Factor XIIIa cross-links fibrin strands, making the clot resistant to fibrinolysis.

Question 15

Which is responsible for fibrinolysis?

Accepted Answer

Tissue plasminogen activator (tPA) — tPA converts plasminogen → plasmin, which digests fibrin and dissolves clots.

Question 16

Which color vial is used for coagulation studies?

Accepted Answer

Light blue — Light blue (sodium citrate) tubes are used for PT, aPTT, and other coagulation tests.

Question 17

Main cause of increased PT?

Accepted Answer

Decreased Factor VII — PT measures the extrinsic pathway; Factor VII deficiency or warfarin (which most affects Factor VII) prolongs PT.

Question 18

Which is NOT released by activated platelets?

Accepted Answer

Urea — Activated platelets release ADP, serotonin, thromboxane A2, and calcium. Urea is a waste product, not released by platelets.

Question 19

Function of antithrombin III?

Accepted Answer

Inhibits thrombin — ATIII is the main physiological inhibitor of thrombin and Factor Xa; heparin greatly enhances its activity.

Question 20

Which test monitors heparin therapy?

Accepted Answer

Thrombin time — Heparin acts on the intrinsic pathway via ATIII; aPTT monitors this with a therapeutic target of 1.5–2.5× control.

Question 21

Main abnormality in von Willebrand disease?

Accepted Answer

Lack of von Willebrand factor — vWD is the most common inherited bleeding disorder, caused by absent or dysfunctional vWF protein.

Question 22

Which is NOT a step in haemostasis?

Accepted Answer

Leukocyte migration — Leukocyte migration is part of the inflammatory response, not a component of haemostasis.

Question 23

Which factor converts prothrombin to thrombin?

Accepted Answer

Factor Xa — Factor Xa, together with Factor Va (prothrombinase complex) on a phospholipid surface, cleaves prothrombin to thrombin.

Question 24

Screening test for the extrinsic pathway?

Accepted Answer

Thrombin time — PT measures the extrinsic (Factor VII + tissue factor) and common pathways.

Question 25

Disorder characterized by low platelet count?

Accepted Answer

Thrombocytopenia — Thrombocytopenia = platelet count <150,000/μL; causes include ITP, bone marrow failure, and HIT.

Question 26

Factor known as the "Stuart-Prower factor"?

Accepted Answer

Factor X — Factor X sits at the junction of intrinsic and extrinsic pathways, entering the common pathway.

Question 27

Main role of platelets in haemostasis?

Accepted Answer

Plug formation — Platelets adhere to damaged endothelium, activate, and aggregate to form the primary platelet plug.

Question 28

Common cause of prolonged bleeding time?

Accepted Answer

Platelet dysfunction — Bleeding time reflects primary haemostasis; platelet disorders prolong it, not coagulation factor deficiencies.

Question 29

Which test result is reported in seconds?

Accepted Answer

PT and APTT — Both PT and aPTT measure the time (in seconds) for plasma to clot under specific conditions.

Question 30

Which is effective in dissolving a clot after repair?

Accepted Answer

Plasminolysin — Plasmin is the active fibrinolytic enzyme that degrades fibrin clots; plasminolysin is another term for plasmin.

Haemostasis MCQs: Master Coagulation & Bleeding Control

Questions, Answers & Explanations