This is a kind of phobia with respect to medical tests. One of the symptoms is raised BP, which as you rightly pointed out is "White Collar Hypertension."
There's nothing to worry about.
Next Steps
You'll find a lot of easy to use electronic BP machines in the market. Get one. Read the instructions and Record your BP daily for 1 week in sitting position. Then, you can take these readings to your doctor to eliminate the influence of the 'white collar hypertension' on your BP readings at your doctor's office.
if you find this fear of medical tests overwhelming, please visit a Psychiatrist for full evaluation.
if you have any other fears, that are difficult to manage, the also, please visit a Psychiatrist for further evaluation
Health Tips
try breathing exercises: take slow and deep breaths in and relase slowly, while you are undergoing any medical procedures