Final answer:
The catheter should be advanced when blood return is seen in the backflash chamber, indicating proper vein entry for IV therapy, and consistent monitoring for infections is crucial.
Step-by-step explanation:
The health care personnel would continue to advance the catheter after an initial stick into a patient's vein if D) Blood return is noted in the backflash chamber of the catheter. This indicates that the catheter is properly placed within the vein, allowing for the administration of IV fluids or medication. The presence of a blood return confirms that the catheter has entered the vein, which is critical for effective intravenous therapy. It's important for health care professionals to monitor patients closely for signs of infection since IV catheter sites can be entry points for pathogens potentially leading to bloodstream infections.