Which of the following can lead to hypovolemic shock?

• A. Infection
• B. Diarrhea
• C. Allergic reaction
• D. Vasodilation

Answer: (B)

Hypovolemic shock happens when circulating blood volume drops significantly, so the heart can’t pump enough blood to organs. Diarrhea fits this mechanism because it can cause a rapid and substantial loss of fluid (and electrolytes) from the gastrointestinal tract, which decreases preload, lowers stroke volume, and reduces cardiac output. If this fluid loss isn’t rapidly compensated, blood pressure falls and organs become underperfused.

Infection can lead to septic (distributive) shock, where blood vessels dilate and become leaky, not primarily due to a loss of volume. An allergic reaction can cause anaphylactic (distributive) shock with airway compromise and vasodilation, again not mainly from fluid loss. Vasodilation lowers resistance and blood pressure, but by itself doesn’t describe the volume deficit that defines hypovolemia.