The most powerful diagnostic tool available to a physician is more revealing than a CT scan, more precise than any blood or urine analysis and far clearer than anything heard through a stethoscope.

It's called talking to the patient.

"It's clearly the most important thing doctors do," said Dr. Robert M. Arnold, professor of medicine at the University of Pittsburgh School of Medicine. "We do it more than anything else. And it is the most sensitive and specific test we can do."

Luckily, talking is also something that can be taught, even to doctors.

As director of the medical school's new Institute for Doctor-Patient Communication, Arnold is in position not only to push research into how communication can be improved, but also make changes in how medical students are trained to become physicians. Pitt has benefited from several faculty who have become interested in the subject, he said, and by "a dean who thinks this is important."

"The fundamental relationship between a doctor and his or her patients is really the soul of the medical profession," Dr. Arthur S. Levine, dean of the medical school and senior vice chancellor for health sciences, said in a statement announcing the institute yesterday.

Arnold, 43, became interested in doctor-patient communication as an outgrowth of his work as a medical ethicist. He said it eventually dawned on him that despite all of the philosophical concepts that he taught medical students, they often lacked the words necessary to translate the concepts into action.

He now holds the Leo H. Criep Chair in Patient Care, an endowed chair established five years ago by the Jewish Healthcare Foundation, the university and the family of the late doctor, a 1920 Pitt grad and former chief of allergy who believed in the importance of the doctor-patient relationship.

Arnold said he has learned that it's possible to teach today's doctors specific skills that can improve their interactions.

"What doctors do a lot is tell people, but they don't ask," Arnold said. If doctors ask more questions before they give their patients instructions or advice, they can avoid some pitfalls.

For instance, doctors often need to know what medications a patient has been taking so that they can make an accurate diagnosis, or so they can avoid prescribing a new drug that will interact with the others. But simply asking, "What other medications are you taking?" often fails to elicit a complete response, he said. Many patients wouldn't think to tell the doctor about the vitamins they take, or about the herbs or other complementary medicines they prescribe themselves.

"It's better to say, 'Tell us about all of the pills you put in your mouth,'" Arnold said.

Just yesterday, a resident working with Arnold asked both that question and a follow-up -- "Are you having any trouble taking them?" The second question, he noted, elicited an important response: The patient did indeed have trouble taking some capsules and so was first emptying the powder out of the capsules and eating the powder. Doing so, however, negated the benefits of that drug.

"We would never have known about that" had the resident failed to ask, he said.

In these days of managed care, when doctors are often pressed for time as they see more patients, one thing they dread to hear from the patient at the end of the appointment is, "Oh, by the way ... ," Arnold said. "That's because 'Oh, by the way' is always a big thing." The key to preventing such a problem occurs at the beginning of the appointment. When the patient says he has come in because of a sore throat and a cold, the physician should ask, "Is there anything else? That way, you get everything at the beginning."

And sometimes, doctors simply have to learn when to do nothing. Physicians often have difficulty handling emotional discussions, Arnold explained. "Docs want to fix things; that's why we became doctors."

Laurel Milberg, the institute's co-director for education, is setting goals for the communication skills that should be taught in each year of the four-year medical school curriculum. The institute also is teaching junior faculty how to teach communication skills to students. Dr. Bruce Ling is the co-director for research.

Some research even has shown how doctors can get patients to do a better job of holding up their side of the conversation.

Suggesting questions that the patient should ask the doctor, or a checklist of information that they should obtain before leaving, can help.