Many Americans who need to see a family physician or specialist may have to wait weeks or even months for an appointment, a new survey suggests.

People living in and around Boston need to have the most patience, according to the survey, which attempted to gauge average wait times for doctor appointments in 15 U.S. metropolitan areas.

Boston residents, the survey suggests, need to wait an average of 70 days for a routine check-up with an obstetrician/gynecologist; 63 days to see a family physician for a standard physical; 40 days to see an orthopedic surgeon to assess a knee injury; and 3 weeks for a check-up with a cardiologist.

Atlanta typically had the shortest wait times — 9 days to see a family physician, for example, and 5 days to see a cardiologist.

The survey was conducted by Merritt Hawkins and Associates, a physician search and consulting firm that is part of AMN Healthcare, a healthcare staffing organization.

Researchers arrived at their findings by attempting to make routine doctor appointments in 15 major metropolitan areas. For each city, they called a minimum of 10 practices in each of five medical fields:

family practice, cardiology, dermatology, ob/gyn and orthopedic surgery.

In cardiology, the survey found, the average wait time exceeded 2 weeks in five metropolitan areas: Minneapolis (47 days), Miami (29 days), San Diego (22 days), Boston (21 days) and Washington, DC (18 days).

In family practice, wait times were 2 weeks or longer in eight

cities: Boston (63 days), Los Angeles (59 days), Washington (30 days), New York and San Diego (24 days), Houston (17 days) and Denver and Detroit, each at 14 days.

Boston was consistently at or near the top in average wait time for each specialty, while other cities tended to vary depending on the field.

This may be related to the fact that Massachusetts now mandates health insurance coverage for residents — a move that, along with increasing the rolls of the insured, has boosted demand for doctor appointments.

Even though Massachusetts has more doctors per capita than any other state, patients are still having difficulty getting an appointment, Merritt Hawkins president Mark Smith said in a new release from the firm.

If national healthcare reform leads to a similar expansion of insurance coverage nationwide, Smith said, long wait times could become an even greater problem.

Along with geographical differences in wait times, the survey also found wide variation in doctors' acceptance of Medicaid, the government health insurance program for the poor.

Minneapolis had the highest rate of Medicaid acceptance, at 82 percent, while Dallas came in last, at 39 percent.

"Merely having medical coverage does not always ensure access to a physician," Smith said. "Many doctors simply can no longer afford to see Medicaid patients."