At least one in 12 patients who die has been diagnosed incorrectly, according to a 2003 analysis in The Journal of the American Medical Association. When trying to figure out the occasional difficult case, doctors sometimes get it wrong. Yet they rarely use the highly accurate computer systems designed to help with the identification of ailments.

Take the example of DXplain, one of the more popular diagnostic software tools around for physicians. DXplain is available for free on the Internet to every licensed health care professional in the United States. Yet fewer than one in 10 physicians has used the program during its more than 20 years on the market, estimated Dr. Edward Hoffer, a key DXplain developer and professor of medicine at the Beth Israel Deaconess Medical Center in Boston.

Many of these computer programs, like DXplain, allow the clinician to plug in patient symptoms and demographic information such as sex, age, race and geography. The computer then compiles a list of possible diagnoses, and the doctor can click away for more information on each medical condition.

Using these programs is time-consuming and cumbersome, and there is not enough evidence that using them improves patient care, noted Dr. Peter Stetson, professor of clinical medical informatics at Columbia University in New York. He views these challenges as opportunities for researchers to improve these products.

But doctors’ psychological barriers may be even harder to overcome than these technical issues.

“The problem with diagnosis is we do not know when we do not know,” said Dr. Joseph Britto, co-founder and developer of a new diagnosis program called Isabel. He estimated that doctors are wrong in about one in 15 cases.

The vast majority of cases doctors see are clear-cut, explained Dr. Michael Cantor, chief medical information officer at Bellevue Hospital in New York. “You don’t need a diagnosis system to tell you that a 55-year-old smoker coming in with chest pain is probably having a heart attack,” added Cantor.

But when a case is not so run-of-the-mill, DXplain’s Hoffer said, physicians may “pigeonhole” it without considering all the evidence. “Doctors who’ve practiced for a long time tend to assume that patients have a common disease they’ve seen before,” said Hoffer.

Physicians also get inadequate feedback on their diagnostic mistakes, explained Eta Berner, an expert on diagnostic support systems and professor of health informatics at the University of Alabama at Birmingham. “They can make the wrong diagnosis, treat it fine and never realize that they made an error.”

Another possible factor leading to mistakes is that doctors are often overconfident in their diagnoses, according to research published in the Journal of General Internal Medicine in 2005. In this study, a group of physicians were asked to list possible diagnoses for some challenging cases and if they would have sought help with their decisions. When they were wrong, they would not have looked for assistance in more than one in three instances.

Given these pitfalls, one way to improve diagnostic accuracy may be to work with doctors’ existing attitudes instead of trying to change them.

“Make it easy for me to do the right thing. Make it hard for me to do the wrong thing,” explained Dr. Abha Agrawal, director of medical informatics at Kings County Hospital Center in Brooklyn.

For instance, researchers are exploring the possibility of integrating DXplain so that it can scan electronic patient records and then pop up with a note when the symptoms and the diagnosis do not match, said Hoffer.

But even then, physicians might ignore these digital reminders, as was shown in a 2005 study in the Journal of the American Medical Informatics Association. “My favorite analogy is the little paper clip guy in Word,” said Berner. “There’s no one I know who doesn’t turn him off immediately.”

Another solution might be to require doctors to consult a computer on every case. “Physicians should not be allowed to make a diagnosis without using a checklist,” said Isabel’s Britto, comparing such a list to take-off and landing protocols in aviation. In his system, such a list can be just one click away from the patient’s record.

Attitudes about computer-assisted diagnosis could also change naturally as a new generation enters the medical field. Younger doctors are more eager to use the technology, according to Dr. Stephen Borowitz, a pediatrician who oversaw the adoption of Isabel at the University of Virginia Health System in Charlottesville, Va. “That cultural shift is already happening,” he said.

Meanwhile, if you are uneasy about your own diagnosis, what should you do? Share your concerns with your doctor and ask for other possibilities. If she can’t provide one, it may be time to get a second opinion.