The head of general surgery at Dartmouth-Hitchcock Medical Center had a remarkably simple idea not long ago: What if the department suggested that surgeons limit prescriptions of narcotic pain pills to a specific number for different kinds of operations?

The results were dramatic: The number of pills prescribed by doctors for five common outpatient surgeries dropped by 53 percent, and patients didn’t consume all the pills they were given, according to a study that will be published this week in the journal Annals of Surgery.

Even veteran surgeons really had no idea how many opioids to send home with their patients, said Richard J. Barth, who is chief of general surgery at the medical center in New Hampshire and led the team that conducted the study.