THURSDAY, July 8 (HealthDayNews) -- About half of the 700,000 cases of suspected appendicitis in the United States each year lack the condition's telltale symptoms -- lower abdominal pain and fever, according to nuclear medicine researchers at Thomas Jefferson University in Philadelphia.

The U.S. Food and Drug Administration has just approved the researchers' diagnostic test that they say should make it easier for doctors to spot and treat these elusive cases.

The NeutroSpec system involves use of a radioactive antibody that binds to the type of infection-fighting white blood cell that is often present in people who have inconclusive symptoms of appendicitis, the researchers said. Doctors can then locate the antibody and infection site by using a device called a gamma camera.

In human trials, NeutroSpec was 60 percent accurate in detecting appendicitis in less than five minutes, and nearly 100 percent accurate in diagnosing the condition within an hour, the researchers said in a statement.

The test could significantly reduce the 15 percent to 30 percent of all appendectomies that prove unnecessary because the organ is actually normal, the scientists said.

To learn more about appendicitis, visit the National Digestive Diseases Information Clearinghouse.