Perhaps you’ve had this nightmare: you’re doubled over with stabbing pain. You feel like you’ve been knifed on your right side. You’ve Googled, gone to WebMD, double-checked the pain is in fact on your right side. It’s your appendix, you know it could burst at any moment—you’re going to need immediate surgery, right?

Probably not. The emergency appendectomy—that wicked, temporarily debilitating, and costly medical procedure performed on 320,000 Americans each year—it turns out, in most cases, is completely unnecessary said David Agus, Director of the University of Southern California’s Center for Applied Molecular Medicine speaking at Fortune’s Brainstorm Health conference in San Diego on Tuesday.

In a recent study in Europe, 70% of patients with appendicitis were treated successfully with antibiotics, Agus says. And those that were not cured with medicine underwent surgery with no complications. Such an approach could prevent more than 200,000 surgeries per year in the U.S.

Yet the appendectomy continues to reign supreme, noted Agus, “because 24/7 we’re taught you have to take it out if there’s appendicitis.” He added of the health care community, “We’re stubborn and pig-headed.”

Agus, author of The Lucky Years: How to Thrive in the Brave New World of Health, sees the community’s recalcitrance as one of the field’s serious challenges. Some of the others: lack of political will, and the system’s focus on treatment, rather than prevention.

“We’re incentivizing [situations] where surgeons get paid to operate. We push to treat,” he said. “We’re not incentivizing to prevent.”

The good news? We’re at inflection point, Agus argues, in terms of technology and know-how: we’re ready to disrupt health care.