Watchful waiting (also watch and wait or WAW) is an approach to a medical problem in which time is allowed to pass before medical intervention or therapy is used. During this time, repeated testing may be performed. Watchful waiting (also watch and wait or WAW) is an approach to a medical problem in which time is allowed to pass before medical intervention or therapy is used. During this time, repeated testing may be performed. Related terms include expectant management, active surveillance and masterly inactivity. The term masterly inactivity is also used in nonmedical contexts. A distinction can be drawn between watchful waiting and medical observation, but some sources equate the terms. Usually, watchful waiting is an outpatient process and may have a duration of months or years. In contrast, medical observation is usually an inpatient process, often involving frequent or even continuous monitoring and may have a duration of hours or days.