SBA — Single Best Answer · Review
Question 421
Pathology → General
Classification
Question
SSBAQuestion Header
A woman develops major acute blood loss. Which sequence most accurately describes the development of hypovolaemic shock?
Question Stem
Select the single best answer.
Options
A
Blood loss -> increased CVP -> increased venous return -> tissue hyperoxia
B
Blood loss -> reduced circulating volume -> reduced venous return -> reduced tissue perfusion -> hypoxia and acidosis
C
Blood loss -> preserved circulating volume -> isolated myocardial pump failure -> acidosis
D
Blood loss -> primary systemic vasodilatation -> hyperdynamic circulation -> DIC
E
Blood loss -> increased cardiac output -> increased tissue perfusion -> respiratory alkalosis
Explanation
Hypovolaemic shock follows loss of blood or plasma, producing reduced effective circulating volume, lower central venous pressure and venous return, hypotension and inadequate tissue perfusion. The resulting tissue hypoxia leads to metabolic acidosis.
Option Validity
A) Hypovolaemia reduces rather than increases central venous pressure and venous return.
C) Acute pump failure without actual loss of circulating volume describes cardiogenic rather than hypovolaemic shock.
D) Marked vasodilatation, increased vascular permeability and possible DIC are features of septic shock rather than the primary sequence after haemorrhage.
E) Major blood loss does not produce the sustained increase in tissue perfusion described.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 5: Pathology. General Pathology, pp.161–175.