Final answer:
The best initial step for ensuring the validity of an unexpectedly high blood pressure reading is to take other vital signs and recheck the pressure after a few minutes to allow the patient to relax.
Step-by-step explanation:
If a medical assistant finds that a patient's blood pressure is significantly higher than usual, the first step they should take to ensure the validity of the reading is C. Take the other vital signs and recheck the blood pressure after a few minutes. This approach allows the patient to relax and may help in obtaining a more accurate reading. Telling the patient to relax and retaking the pressure immediately may not give the patient enough time to calm down if they are anxious, which could affect the reading. Asking another medical assistant to take the blood pressure might not account for the possibility that the patient has experienced a short-term increase in blood pressure due to stress or other factors.
It is also important to consider the concept of "white coat disease," where a patient's blood pressure may rise due to the anxiety of being examined by a healthcare professional. Medical professionals use a blood pressure cuff and a stethoscope to measure blood pressure, a common and vital procedure, and sometimes they may use automated equipment for measuring blood pressure or utilize a small instrument that wraps around a patient's wrist for convenience and accuracy.