Federal officials on Wednesday urged — but did not require — health care providers to delay elective medical and dental procedures.

Government pressure has been mounting on hospitals and dentists to postpone nonessential care, but hospital officials say the distinction between essential and nonessential care is not always easy to discern. Hospital groups expressed concern this week that "arbitrary directives" from government officials could stand in the way of important non-virus-related care.

As of Wednesday night, at least four major health systems in Minnesota, including Mayo Clinic, announced decisions to postpone elective care in various ways. Hennepin Healthcare in Minneapolis said it's canceling "non-essential/non-emergency" clinic visits at all of its care sites.

Late Wednesday, the federal Centers for Medicare and Medicaid Services issued guidelines outlining a decisionmaking process that balances resource conservation with personal needs.

"CMS recognizes that conservation of critical resources such as ventilators and Personal Protective Equipment is essential, as well as limiting exposure of patients and staff to the SARS-CoV-2 virus," CMS' two-page guidance says. "These considerations will assist in the management of vital healthcare resources during this … emergency."

Care decisions are ultimately left to the clinician, patient, hospital and state and local public health officials. But CMS strongly urges postponing nonessential dental work because of high risks of transmission. Decisions about medical care should include not just individual need, but overall resource conservation.

The guidelines were praised by the American Hospital Association and the American Medical Association.

"It's important to recognize that the cancellation of elective procedures — which the medical community needs to be prepared to implement — should be determined at the local, community level in consultation with hospitals and the clinical recommendations of physicians and nurses," the American Hospital Association in Washington said.

The Chicago-based American College of Surgeons said last week that all scheduled elective procedures should be reviewed and potentially postponed until after the infection rate for COVID-19 reaches its predicted "inflection point."

But the group noted that it's not possible to define the medical urgency of a case solely by whether it's on an elective surgery schedule. The "vast majority" of these surgeries are used to treat progressive diseases like cancer, vascular disease and organ failure, which will continue to worsen.

Minnesota health system Allina Health is canceling elective procedures like bariatric surgery, but considering the factors in many other cases.

Dr. Alison Peterson, vice president of medical affairs at Allina's United Hospital in St. Paul, said that if the surgeon wants to proceed with a discretionary case at an Allina hospital, the anesthesiologist and medical director of the operating room have to agree. An appeals process can escalate the question through the hospital's medical staff, if a dispute arises.

But for surgeries that are postponed, like those to treat pain in the spine or knees, Peterson said the patient isn't left hanging.

"We're not just telling patients, sorry, you can't have surgery," she said. "We refer them back to their primary care physician so we can manage any symptoms. That's actually part of the workflow, that the surgeon makes sure the patient is handed back to the referring provider who will be able to assist them during the period surgery is deferred."