What symptom indicates an infection at the IV site?

Swelling and redness at the IV site are classic signs of infection. These symptoms occur due to the body's inflammatory response to the presence of pathogens, which leads to increased blood flow and fluid accumulation in the affected area. When an infection develops, you may notice the skin around the IV site becoming red and swollen, and it may feel warm to the touch. These visual and tactile indicators are critical for identifying potential complications related to intravenous therapy, allowing for prompt intervention to prevent further complications.

The other options do not specifically indicate an infection at the IV site. Fluid intake being greater than urinary output relates to hydration status or renal function rather than infection. Elevated blood pressure can result from various factors, including pain, anxiety, or fluid overload, but it is not specific to infection at the IV site. Obstruction of a blood vessel may cause symptoms like swelling or pain but doesn't directly point to an infection. Thus, swelling and redness are the most definitive indicators of an infection.