If you’re thinking about getting a mammogram in the Dallas-Fort Worth area, you might check carefully, because the cost can vary from $50 to as much as $1,045.

How about an initial routine gynecologic exam? Around Phoenix, those prices can range from $72 to $388.

According to an analysis released last week, shopping around for women’s health care can be worth the effort, with mammograms and other routine services often costing far more in one office than in another. Researchers at Castlight Health, a company that helps businesses analyze health care prices, looked at 179 metropolitan areas and found that mammogram prices varied greatly in Atlanta, Houston, Los Angeles, Miami, Philadelphia and Seattle, among other cities.

In the Washington-Baltimore region, which includes Virginia and West Virginia, mammogram prices ranged from $150 to $663, with the average cost $390. The entire mammogram price chart can be found at www.khn.org.

“The variation was shocking,” said Jonathan Rende, chief of research and development for Castlight, which is based in San Francisco and collects billing records from employers that show the prices insurers and patients pay. “It speaks to how broken the health care system is.”

The Castlight study is one of the first to look at price variation in women’s health services, and it did not explain what may be causing the disparities or publish the names of providers. However, other studies have identified a host of influences. Private insurers sometimes strike markedly different deals with hospitals, labs and doctors in negotiations that are driven by market power as much as the actual cost of care.

And that leaves health care consumers in the dark. They are in weak positions to shop around as most medical professionals and insurers do not publish prices or make it easy to get quotes. Patients frequently defer to their doctors’ recommendations for where to get a test, and those physicians rarely consider price.

Not every type of procedure Castlight examined had gigantic variations. The widest price difference for a follow-up visit with an obstetrician and gynecologist was in Phoenix, where the cheapest visit cost $57 and the most expensive one cost $137.

But Castlight found price differences in tests for the human papillomavirus — which is linked to the risk of cervical cancer — of 10 times or more in the majority of the major metropolitan regions it examined. An HPV test in the Philadelphia-Atlantic City, New Jersey area ranged from $32 to $626.

Castlight also found prices varied significantly from one region to another beyond what could be attributed to cost-of-living differences. The average price for a mammogram ranged from $485 in Sacramento to $159 in Cincinnati, Ohio. The average HPV test in Indianapolis was $165, five times the $32 price in Charlotte, North Carolina.