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Question 350
Physiology → Haematology
Classification
Question
SSBAQuestion Header
A patient has a haemostatic disorder affecting platelet plugging or capillary integrity rather than formation of the fibrin clot.
Question Stem
Which laboratory finding most directly reflects this abnormality?
Options
A
Prolonged bleeding time
B
Prolonged clotting time due to factor VIII deficiency
C
Prolonged PT due to factor VII abnormality
D
Prolonged APTT due to factor IX abnormality
E
Prolonged PT due to factor II abnormality
Explanation
Bleeding time is determined by platelets and vascular contraction and is prolonged in purpura caused by capillary or platelet disorders. By contrast, abnormalities of specific coagulation factors are assessed by clotting time, PT or APTT according to the pathway involved.
Option Validity
B) Factor VIII deficiency affects coagulation and prolongs clotting time; it does not represent failure of platelet plugging or capillary integrity.
C) Factor VII abnormality prolongs PT through an extrinsic-pathway coagulation defect rather than a platelet or capillary defect.
D) Factor IX abnormality prolongs APTT through an intrinsic-pathway coagulation defect.
E) Factor II abnormality can prolong PT because factor II participates in the coagulation pathway; this is distinct from the platelet and vascular determinants of bleeding time.
Further Reading
Saxena. Textbook for MRCOG-1. Physiology - Haematology - Tests of Coagulation, pp.71–72.