My gastroenterologist of seven years recently began working at a new practice, one owned by a large medical center. When I contacted her about a colonoscopy, we discussed my precolonoscopy prep and diet and the scope she’d use, then scheduled an appointment at her new hospital.

What my doctor neglected to share with me was that—because of changes related to her new practice—she wouldn’t be performing my procedure.

Like my gastroenterologist, doctors throughout the country are leaving their private practices in droves to become employees of hospital-owned practices and multi­specialty clinics.

From July 2012 to July 2015, the number of hospital-employed physicians increased by 50 percent, and it’s estimated that only about 1 in 3 doctors remains in private practice. (This is largely because hospitals and healthcare systems are buying up practices to attract more patients and because government and insurance regulations are becoming too labor-intensive for small practices.)

These changes in doctors’ employment status come with a host of new conditions that can affect your care. Three key examples:

Your Office Visit Might Change

When your doctor leaves private practice for a hospital-owned practice, you may find that he or she has new office staff and hours, and new rules about cancellations—and that the length of appointments has changed.

Even if you’ve been seeing your doctor for years, you’ll probably need to fill out new registration forms at your first appointment at the new practice. And because the new practice may use a different electronic medical records system and might not yet have access to your information, take a list of your medications, supplements, surgeries, and diagnoses.

Your doctor might also get slowed down while learning that new system, as mine was, so be patient.

Your Costs Might Increase

Several factors might affect what you’re asked to pay. For example, when doctors join a hospital-owned practice, they’ll probably begin accepting some new insur­ance plans and dropping others. So ask the billing department whether the practice still participates in your plan; otherwise you could be stuck with out-of-network bills.

Even if your doctor still accepts your insurance, your coinsurance (the percentage of the bill you pay out of pocket after insurance pays its portion) could go up. This is because your doctor may start charging his new employer’s prices for tests and other services. Check before­hand with the office billing staff.

The hospital that bought your doctor’s practice may designate his office an outpatient clinic and can legally charge you a facility fee if procedures or tests are performed there. Ask about facility fees ahead of time.

The 2015 Bipartisan Budget Act prevents health systems from billing those on Medicare for facility fees at practices acquired on or after Nov. 2, 2015, but systems can continue charging for those purchased beforehand.

You Might See New Providers

By joining a larger group of healthcare providers, your physician is likely to provide you with access to a broader network of on-call and consulting doctors who can easily share information with each other about your health. This is often beneficial.

But not always. Just before my pre­colon­oscopy sedation was administered, it occurred to me to make sure my doctor—who had not yet approached my bedside in the outpatient procedure suite—would be performing the test.

I was stunned to discover that a doctor in training was scheduled to do the test and that my doctor was only supposed to be supervising. Her new medical center is a teaching facility, and trainees perform such tests as part of their education.

Most patients’ bills of rights give you the right to know the names, positions, and functions of all hospital staff involved in your care and to refuse their treatment, examination, or observation. And doctors in training are mandated to inform patients of their respective roles.

But as in my case, these rules are sometimes overlooked. So if your doctor joins a new practice, it’s important to ask ahead of time who you will be seeing in the office and who will perform any scheduled tests or surgery.

Asking questions before my colonoscopy gave me the opportunity to request that my gastroenterologist perform it herself.

Editor's Note: This article also appeared in the March 2017 issue of Consumer Reports on Health.