Washington ? Old checklist for doctors: order that test, write that prescription. New checklist for doctors: first ask yourself if the patient really needs it.

Nine medical societies representing nearly 375,000 physicians are challenging the widely held perception that more health care is better, releasing lists today of tests and treatments their members should no longer automatically order.

The 45 items listed include most repeat colonoscopies within 10 years of a first such test, early imaging for most back pain, brain scans for patients who fainted but didn’t have seizures, and antibiotics for mild- to-moderate sinus distress.

Also on the list: heart imaging stress tests for patients without coronary symptoms. And a particularly sobering recommendation calls for cancer doctors to stop treating tumors in end-stage patients who have not responded to multiple therapies and are ineligible for experimental treatments.

Dr. Christine Cassel, president of the American Board of Internal Medicine, said the goal is to reduce wasteful spending without harming patients. She suggested some may benefit by avoiding known risks associated with medical tests, such as exposure to radiation.

“We all know there is overuse and waste in the system, so let’s have the doctors take responsibility for that and look at the things that are overused,” said Cassel. “We’re doing this because we think we don’t need to ration health care if we get rid of waste.” Her group sets standards and oversees board certification for many medical specialties.

The recommendations come at a time when American health care is undergoing far-reaching changes. No matter what the Supreme Court decides on President Barack Obama’s health overhaul, employers, lawmakers, insurers and many doctors are questioning how the United States spends far more on medical care than any other economically advanced country and still produces mediocre results overall.

Until now, the health care system has rewarded doctors for volume. Now the focus is shifting to paying for results and coordination. That explains the urgency for doctors themselves to identify areas of questionable spending.

It’s unclear how much money would be saved if doctors followed the 45 recommendations rigorously. Probably tens of billions of dollars, and maybe hundreds of billions over time. That would help, but come nowhere near solving, the problem of high health care costs.

The nation’s medical bill hit $2.6 trillion in 2010. A major quandary for cost-cutters is that most of the spending is attributable to a relatively small share of very sick people. Just 5 percent of patients accounted for half the total costs among privately insured people, according to a recent study from the IMS Institute for Healthcare Informatics.