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Question 309
Physiology → Haematology
Classification
Question
SSBAOptions
Explanation
Bleeding time measures the interval from the onset of oozing until bleeding arrests and depends on platelet function and vascular contraction. It is prolonged in purpura and disorders involving capillaries or platelets.
Option Validity
A) PT assesses the extrinsic and common coagulation pathways rather than primary platelet and vascular haemostasis. An isolated platelet or capillary disorder therefore does not primarily correspond to an abnormal PT.
B) APTT assesses the intrinsic and common coagulation pathways. The stem instead describes the platelet and vascular components assessed by bleeding time.
D) Platelet or capillary abnormalities do not necessarily prolong both PT and APTT. These tests evaluate coagulation pathways rather than the primary haemostatic mechanism described.
E) ESR is a measure of erythrocyte sedimentation and is influenced by cellular and plasma factors. It is not the test used to assess platelet or capillary haemostasis.
Further Reading
Saxena. Textbook for MRCOG-1. Physiology - Haematology - Bleeding Time, p.71.