Nearly half of the U.S. doctors fail to report incompetent and unethical colleagues, even though they agree that such errors should immediately be reported, a survey revealed on Monday.

The survey, led by researchers from Massachusetts General Hospital, questioned nearly 1,700 doctors between November 2003 and June 2004 about their beliefs and practices regarding medicine.

The results show that most doctors adhere to strict standards or professionalism regarding medical mistakes, patient privacy and appropriate patient relationships.

About 93 percent of the interviewed doctors agreed that they should report all serious medical errors they observe, but only 46 percent of them, confronting with this problem in the last three years, reported it to the authorities. Also 96 percent agreed that they should report any physician who is significantly impaired or incompetent, while only 45 percent said they were aware of bad behavior by doctors that they did not report.

"There is a measurable disconnect between what physicians say they think is the right thing to do and what they actually do," said Eric Campbell of Massachusetts General Hospital and Harvard Medical School in Boston, who led the survey.

In addition, the survey found that doctors had ordered tests that were not always necessary, such as MRI.

According to Dr. James Thompson, chief executive officer of the federation of State Medical Boards, there is not a lot to be done to assist those doctors who are actually struggling to become competent.

"There are restrictions on state medical boards that inhibit their ability to go after physicians aggressively. There are very few places where they can send them for remediation. There are state medical boards that don't even have their own teams of investigators. There are state medical boards that are, quite frankly, underfunded and understaffed," Thompson said.

The survey also contained questions about doctor-patient interaction. One out of 10 doctors admitted to violating patient confidentiality. About 15 percent said patients should not be informed about any medical mistake. Surprisingly, 9 percent of doctors said that it was sometimes appropriate to have a sexual relationship with patients.

“The vast majority believes in the tenets of professionalism, and the majority of physicians observe those tenets in most respects. There are significant and worrisome departures that need attention from the profession and regulatory authorities,” says Dr. Blumenthal, director of the Institute for Health Policy at Massachusetts General Hospital and senior author on the paper.

The survey comes after an Institute of Medicine report, issued back in 2000, found that an estimated 98 thousand people die in hospitals each year due to errors by doctors.

The results of the survey are reported in today's issue of The Annals of Internal Medicine.