What you can expect
Having a blood pressure test is often a routine part of a medical appointment. The test may be performed by a nurse or technician.
The test is performed best while you're seated in a chair in the examining room. Your arm should be supported, resting on a table at heart level, both feet flat on the floor and back supported by the chair.
Your nurse or technician will wrap an inflatable cuff around the top part of your arm so that the bottom of the cuff is just above your elbow. The cuff is attached to a dial, digital display or a device that looks similar to a thermometer. This equipment is called a sphygmomanometer (sfig-moe-muh-NOM-uh-tur).
Your nurse or technician will generally check blood pressure in both arms to determine if there is a difference. It's important to use an appropriate-sized arm cuff and a properly calibrated device.
Throughout the test, you should try not to talk or move your arm. The nurse or technician will feel the pulse at your wrist and then take a reading with the sphygmomanometer, checking for when the pulse is felt as the air deflates from the cuff. This is so he or she can figure out how much air to pump into the cuff to accurately measure your blood pressure.
Once the nurse or technician finds a pulse from an artery, he or she will position the stethoscope above the elbow to listen for the blood flow. Then he or she will begin inflating the cuff with a small hand pump. The nurse or technician will inflate the cuff to momentarily stop the blood flow through the artery in your arm.
Then the nurse or technician will open a valve on the hand pump to slowly release the air in the cuff. He or she will continue to listen to your pulse with a stethoscope to record your systolic and diastolic blood pressure.
Systolic pressure — the top number of your blood pressure reading — is the pressure of the blood flow when your heart muscle contracts, pumping blood. Diastolic pressure — the bottom number of your blood pressure reading — is the pressure measured between heartbeats. Blood pressure is measured in millimeters of mercury, which is abbreviated mm Hg.
It's also possible your blood pressure will be evaluated using a machine that automatically measures the pressure in your pulse to determine your systolic and diastolic blood pressure. If this is the case, it's not necessary for the nurse or technician to search for your pulse with a stethoscope.
Whether your blood pressure is measured by hand or with an automatic machine, it takes about a minute to complete a single blood pressure measurement.
After the procedure
The nurse or technician taking your blood pressure can tell you what your blood pressure is immediately after the test is over. Your doctor may discuss what the results mean if your blood pressure test shows that you have high or low blood pressure.
If your doctor thinks you may have high or low blood pressure and is trying to decide the best treatment options for you, you'll need to have at least three follow-up appointments to have your blood pressure checked. This is because your blood pressure can vary from moment to moment and day to day. Also for this reason, you'll be given multiple blood pressure tests during one visit. This is most frequently done in a quiet setting with automated devices that record a series of blood pressure measurements over a few minutes and average the values.
Your doctor will look at the results of each of your blood pressure tests to see if you need treatment. You may also be instructed to take several blood pressure readings at home. Check with your doctor to ensure your home blood pressure monitor has been validated. Have your doctor watch you use the device to see if you're doing it properly. Make sure to use a properly fitting cuff. Once a year, check that your monitor is accurate by bringing it to your doctor's office and comparing your monitor's readings with those taken by the doctor. Home blood pressure monitoring isn't a substitute for visits to your doctor, and home blood pressure monitors may have some limitations.
Tracking your blood pressure readings
It can be helpful in diagnosing or monitoring high blood pressure if you record your readings in a blood pressure log, whether on paper or electronically, such as in an online personal health record or blood pressure tracker, for example. This gives you the option of sharing your data with your health care providers and family members.
Some blood pressure monitors can be connected directly or wirelessly to your computer or cellphone, making it easy to transfer the information to an online record.