When bone surgeons at George Washington University Hospital prepare to operate, they take the usual precautions: mask, gown, rubber gloves. And over the head, just in case, a transparent plastic globe connected to an air supply.

"We don't test every patient that comes in, so we just don't know," said Dr. Ralph G. DePalma, the hospital's chief of surgery. "But we don't leave our patients. Period."

What DePalma and his colleagues don't know is whether their patients are infected with human immunodeficiency virus (HIV), the virus that causes AIDS. The solution employed at GW -- to beef up precautions on the assumption that any patient could be a carrier -- reflects the position agreed upon by the American Medical Association in November: No patient may be turned away because of a doctor's fear of contracting AIDS. It is a position that many doctors are embracing wholeheartedly, others are accepting with hesitation and a few are rejecting flat out.

The fear some doctors have is well-grounded in theory, if not in actual experience. AIDS is a blood-borne disease, and surgeons often are awash in blood at the end of an operation. Sometimes, they cut their own skin.

"Bone is very sharp, like glass," said Washington orthopedic surgeon William Gentry. "We use double gloves, but gloves are only so strong." Sharp instruments are used all the time.

Gentry does not turn away AIDS patients -- he has treated several -- but sympathizes with doctors who are fearful. He is aware that no doctor is known to have been infected by a patient, and that only 13 of the thousands of nurses, lab workers and technicians who treat patients or handle blood samples containing the virus -- often in concentrated form -- have been infected with HIV, usually as the result of accidental needle sticks.

It was fear of infection that led a Lewes, Del., doctor last summer to refuse to treat a Washington man injured at the beach. The surgeon demanded proof that the man was not infected before operating on his foot. Ultimately, the patient did not need surgery, but he had to be flown to Washington by helicopter to learn that.

In New York City, the Human Rights Commission received an estimated 145 complaints against doctors and dentists who refused to treat AIDS patients.

The denial of emergency care is universally scorned. "Who else is going to do it?" said Gentry, who has practiced for 23 years and works regularly in Suburban Hospital's emergency room. "If you can't, you have to get out. Do something else."

But even routine care of AIDS patients requires what doctors call "invasive" procedures by specialists in a variety of fields. Biopsies need to be taken, intravenous tubes implanted. Sometimes, the spleen must be removed. These are the sort of life-prolonging steps that cannot be avoided and that have led hospitals to improve operating room procedures. "No operation needs to be messy," said GW's DePalma. "Things have gotten a lot tighter."

Others contend that doctors have always been allowed to turn away patients for a variety of reasons, such as personality conflict or fear of a lawsuit. What's more, they say, it is the AIDS patients themselves who stand to suffer most if treated by unwilling doctors.

"Many physicians are put in the unique position of coming into daily contact with and caring for two population groups {homosexuals and intravenous drug users} with which, on the whole, they would prefer not to associate," Washington neurologist Richard Restak wrote recently. The tension resulting from that uncomfortable association, coupled with fear of AIDS infection, could make a doctor simply too flustered to provide proper care, Restak contends.

Orthopedist Gentry agrees that people seeking treatment of non-urgent problems can be referred to doctors accustomed to treating patients with AIDS, "as long as you can do it without harming the patient."

But it may be patients without AIDS -- the estimated 1.5 million Americans carrying the virus but exhibiting no symptoms -- who most worry physicians. The outspoken Restak has proposed a "no test, no operation" policy, requiring all patients to undergo a blood test for AIDS antibodies. If testing isn't done openly, Restakwarns, doctors may begin doing the tests in secret.

But mandatory testing is unacceptable to gay rights groups, who point out that people infected with AIDS are frequently denied insurance, evicted from their homes and fired from their jobs. "If there were no discriminatory impact from someone's HIV status, then it wouldn't matter," said Urvashi Vaid, public information director of the Gay and Lesbian Task Force in Washington.

The Centers for Disease Control advise that hospital patients be tested but only with their consent and with careful counseling.

Surgeons like GW's DePalma, whose hospital handles a large portion of the city's AIDS patients, think that until the housing and job rights of AIDS carriers and gay men are federally protected, mandatory testing is not acceptable.

More central, DePalma thinks, is the fact that doctors have traditionally put the welfare of patients before their own. At the turn of the century, two out of every hundred medical students died of tuberculosis that they from their patients -- a disease just as deadly as AIDS and far more contagious.

"We've had leprosy, bubonic plague, syphilis -- terrible lethal diseases," DePalma said. "The medical profession has always dealt with them. It must continue to do so. This is our moral obligation."