During septic shock, what happens to circulating fluid?

• A. It is retained in the vascular space
• B. It leaks into the interstitial space
• C. It becomes hyperviscous
• D. It is rapidly converted to plasma

Answer: (B)

In septic shock, inflammatory mediators raise vascular permeability, so fluid normally contained in the blood vessels leaks into the interstitial space. This shifts volume out of the intravascular compartment (third spacing), contributing to hypovolemia, hypotension, and reduced tissue perfusion. Hence circulating fluid moves into the interstitial space. The other ideas don’t fit: fluid isn’t retained in the vascular space, blood viscosity isn’t characteristically increased, and there isn’t a rapid conversion of fluid into plasma.