As might be expected in a country where the price of a knee X-ray can vary by a factor of well over 10, labs so far are charging between $51 (the Medicare reimbursement rate) to more than $100 for the test. How much will insurers cover?

Those testing laboratories want to be paid — and now. Last week the American Clinical Laboratory Association, an industry group, complained that they were being overlooked in the coronavirus package.

“Collectively, these labs have completed over 234,000 tests to date, and nearly quadrupled our daily test capacity over the past week,” Julie Khani, president of A.C.L.A., said in a statement. “They are still waiting for reimbursement for tests performed. In many cases, labs are receiving specimens with incomplete or no insurance information, and are burdened with absorbing the cost.”

There are few provisions in the relief packages to ensure that patients will be protected from large medical bills related to testing, evaluation or treatment — especially since so much of it is taking place in a financial high-risk setting for patients: the emergency room.

In a study last year, about one in six visits to an emergency room or stays in a hospital had at least one out-of-network charge, increasing the risk of patients’ receiving surprise medical bills, many demanding patient payment.

That is in large part because many in-network emergency rooms are staffed by doctors who work for private companies, which are not in the same networks. In a Texas study, more than 30 percent of E.R. physician services were out-of-network — and most of those services were delivered at in-network hospitals.

The doctor who saw Mr. Cencini works with Emergency Care Services of New York, which provides physicians on contract to hospitals and works with some but not all insurers. It is affiliated with TeamHealth, which is a medical staffing business owned by the private equity firm Blackstone and has come under fire for generating surprise bills.