A 42-year-old man has had a rocky course for the 3 days following a bowel resection for intestinal perforation due to inflammatory bowel disease. His CVP had been 12 to 14 but is now 6, in the face of diminished blood pressure and oliguria. Which of the following is the most likely etiology of his hypotension?

**Core Concept**
The patient's clinical presentation suggests hypovolemic shock, which is characterized by decreased **cardiac preload**, leading to reduced **cardiac output**. This condition can arise from various causes, including bleeding, dehydration, or third spacing of fluids.

**Why the Correct Answer is Right**
Given the context of recent bowel resection and the drop in **central venous pressure (CVP)** from 12-14 to 6, along with **diminished blood pressure** and **oliguria**, the most likely cause is hypovolemia. The decrease in CVP indicates a decrease in the volume of blood returning to the heart, which can lead to a decrease in **stroke volume** and subsequently **cardiac output**, resulting in hypotension.

**Why Each Wrong Option is Incorrect**
**Option A:** Not provided, but typically would be an incorrect choice due to lack of information or relevance to the scenario.
**Option B:** Not provided, but could be incorrect if it suggested a cause not supported by the clinical findings, such as cardiogenic shock without evidence of cardiac dysfunction.
**Option C:** Not provided, but might be incorrect if it proposed a distributive cause of shock without signs of vasodilation or evidence of sepsis.
**Option D:** Not provided, but could be incorrect if it implied an obstructive cause without signs of physical obstruction to blood flow.

**Clinical Pearl / High-Yield Fact**
In post-surgical patients, especially those with recent bowel resection, it's crucial to monitor for signs of hypovolemia, as it can quickly lead to hypotension and organ hypoperfusion. Early recognition and fluid resuscitation are key to preventing further complications.

**Correct Answer:** D. Hypovolemia.

✓ Correct Answer: D. Gram-negative sepsis