ABPM means 24-hour ambulatory blood pressure monitoring. It is a method of measuring blood pressure over a total of 24 hours. The usual monitors include an arm cuff worn continuously, attached to a tube, and an air pump worn on a sling. Blood pressure is recorded every 15 minutes during the day and off and on during the night.
 
ABPM is more accurate than other methods because it records your blood pressure at different times during the day. As a result, these measurements provide an average BP reading that is more accurate than a single measurement taken only once.