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Question 359
Physiology → Haematology
Classification
Question
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Two identical small skin wounds are compared. One limb is warm and dependent; the other is cooler and elevated.
Question Stem
Which wound would be expected to bleed more, and why?
Options
A
The elevated limb, because elevation increases intravascular pressure.
B
The cooler limb, because cold dilates cutaneous vessels.
C
The elevated cooler limb, because both interventions increase local blood flow.
D
Both wounds equally, because temperature and limb position do not affect initial bleeding.
E
The warm dependent limb, because warmth dilates cutaneous vessels and lack of elevation preserves higher intravascular pressure.
Explanation
Bleeding from a small skin cut is greater from warm skin because warmth dilates cutaneous blood vessels. Elevation reduces bleeding because intravascular pressure is reduced in the elevated limb. A warm dependent limb therefore combines the conditions favouring greater bleeding.
Option Validity
A) Elevation reduces rather than increases intravascular pressure and therefore reduces bleeding.
B) Warmth, not cold, dilates cutaneous blood vessels and increases bleeding from a small cut.
C) Cooling does not produce the described vasodilating effect, and elevation reduces intravascular pressure.
D) Both temperature and limb position influence bleeding from a small skin wound.
Further Reading
Saxena. Textbook for MRCOG-1. Physiology - Haematology - Prevention of Initial Blood Loss after Injury, p.71.