The pressure cuff + stethoscope combo is called a sphygmomanometer. It's a pretty fascinating piece of technology: A heartbeat is only audible in the earpiece when the cuff is compressing between someone's systolic and diastolic pressure.

To use it, you get the cuff pressure high enough that you stop hearing a heartbeat in the earpiece. Start releasing pressure slowly. As it comes down, take note of where on the dial you start hearing the heartbeat. That's systolic pressure. Keep listening, and take note of where you stop hearing the heartbeat. That's diastolic pressure.

Using one feels kind of magic.

I have a much higher BP when I first go to the office than after I'm sitting in the exam room for a bit.

Usually they call me back to the hallway where they check my weight, then have me sit in a chair and check my temperature, pulse ox and BP, with maybe only a minute sitting down before they do the BP check. My BP is usually in the "hypertension" range there.

But, if they come back to the exam room after I've been sitting in that quiet room for 5 or 10 minutes and check my BP , it's almost always in the "normal" BP range (same as what I see when I check it at home).

Doctor calls it "white coat hypertension", I call it "rushed BP check in the hallway".

Or, maybe you have "white coat syndrome" [1]. This is closely related to "pretty lady syndrome".

[1] https://en.wikipedia.org/wiki/White_coat_hypertension

If the nurse got a reading well outside normal range she should have repeated it to confirm, especially if it was inconsistent with your overall presentation.

If you purchase a home BP monitor, it will include instructions on how to take readings, like these:

https://www.heart.org/en/health-topics/high-blood-pressure/u...

Then you will notice when your HCP ignores those instructions, like wrapping the cuff around your shirt-sleeve, or prompting you to talk while the measurement is taken, or allowing you sit with your legs crossed.

BP monitors are often poorly calibrated. The instructions for my home monitors suggest bringing the device into the clinic for calibration, and then the clinician says "we don't do that!"

Manual sphygmomanometer readings won't have an automatic digital readout, and require the human HCP to interpret, announce and record the numbers.