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Question 422
Pathology → General
Classification
Question
SSBAQuestion Header
Following tissue injury, early fluid movement from the microcirculation is relatively protein-poor. As acute inflammation progresses, the extravascular fluid becomes protein-rich. Which vascular change most directly accounts for this transition?
Question Stem
Select the single best answer.
Options
A
Increased hydrostatic pressure alone
B
Increased vascular permeability to plasma proteins
C
Reduced central venous pressure
D
Increased plasma oncotic pressure
E
Lymphatic obstruction
Explanation
Early vasodilatation increases hydrostatic pressure and can promote relatively protein-poor transudation. The characteristic protein-rich inflammatory exudate develops when vascular permeability increases sufficiently to permit plasma proteins to escape from the circulation.
Option Validity
A) Increased hydrostatic pressure can promote transudation but does not by itself account for the protein-rich inflammatory exudate.
C) Reduced central venous pressure is not the mechanism producing inflammatory exudation.
D) Increased plasma oncotic pressure would favour retention of fluid within the circulation.
E) Lymphatic obstruction can cause oedema but is not the defining vascular mechanism producing an acute inflammatory exudate.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 5: Pathology. General Pathology, pp.161–175.