Blue Cross Blue Shield of Texas, which has over 5 million members, provided similar examples. An endoscopy procedure, used to examine the digestive tract, can cost from $216 to almost $4,300 in North Texas, a spokesman said.

If more people were aware of such gaps, they might appreciate the value of shopping around. The online tools offered by insurers, providers and others can include detailed estimates for deductibles and total out-of-pocket costs. And some procedures are well-suited for comparison shopping.

At Baylor Scott & White Health, about half the searches on its estimator tool are for maternity care, and next up are surgeries and radiology scans. With Baylor’s tool, patients add their insurance, get the negotiated price (not list prices) and get an estimate for their costs — along with ways to pay off the bill with no interest.

“The more information we can provide to patients, the better,” said Sarah Knodel, Baylor’s senior vice president of revenue cycle. “We’re trying to help them navigate a very complex ecosystem.”

Baylor started working on an internal estimating tool five years ago and has produced over 7 million estimates, including for those who walk in for care. But the online self-service estimator has been used by relatively few patients, the company said.

UnitedHealthcare has seen a sharp increase in one metric related to its shopping tool. Last year, members got estimates for $13.7 billion in care, up from $5.5 billion in estimates in 2017, the company said. That one-year increase was several times larger than in 2016 and 2017.

“We’ve seen our members taking more action,” said Katherine Bisek, vice president of strategic initiatives for UnitedHealthcare. “It’s really taking flight.”