Final answer:
The medical assistant can use an alcohol-based hand rub after measuring a patient's apical pulse, which involves less risk of contamination compared to other activities.
Step-by-step explanation:
It is appropriate for the medical assistant to use an alcohol-based hand rub as the only method of hand hygiene after measuring a patient's apical pulse. Unlike other activities mentioned, measuring an apical pulse typically involves less risk of contamination. The CDC outlines a rigorous handwashing protocol for activities that pose a higher risk of infection, such as after using the restroom, assisting with surgeries like a laceration repair, or after contact with bodily fluids during procedures like a dressing change. In these cases, thorough handwashing with soap and water is necessary.