Final answer:
The most urgent finding to report is that the stoma is purple in color, indicating potential necrosis or compromised blood flow, which is a medical emergency.
Step-by-step explanation:
Among the findings reported, the priority for the nurse to report to the provider is option C: The stoma is purple in color. A purple stoma indicates impaired blood flow or necrosis and is a medical emergency. A healthy stoma should be pink to red in color, indicating good perfusion. Dark green liquid stool with a small amount of blood right after surgery (option A) can be normal as the bowel is starting to function. The output of 1,000 mL for the past 24 hours (option B) is within the expected range postoperatively. Decreased output from the NG tube (option D) could indicate reduced gastric secretions and is not immediately concerning but should be monitored. Hence, a purple stoma requires urgent attention to prevent further complications.