One of the biggest complaints about the American health care system is tests that are both expensive and needless. This is a report from the front lines of one expensive test that saved me from lots of grief.

I'm almost 500 miles from my home in Boulder, Colorado, passing through the little Southwestern Colorado town of Durango. Fewer than 20,000 people live here, and I didn't know any of them.

But I had a stomach ache that started at dinner Wednesday. By midnight I was feeling bad enough...