Grandma Katherine needs a hip replacement.

At 62, she doesn't fit the eligibility criteria for Medicare, but is able to pay for the surgery out-of-pocket. She doesn't have high blood pressure, diabetes, or heart issues. The only pills she takes are her daily vitamins and she doesn't smoke or drink.

How much do you think Katherine's surgery (including hospital stay) will cost?

If you guessed any dollar amount, then you're doing better than 84 percent of U.S. hospitals, according to a new report.

Researchers from the University of Iowa, Carver College of Medicine conducted a ‘secret shopper' survey, posing as the grandchildren of the fictitious Katherine and calling a list of hospitals that included both top-ranked and randomly-selected institutions.

They wanted to examine how easy it would be for a senior's family members to obtain a price estimate for a common, elective surgical procedure, such as a hip replacement.

The answer: pretty difficult.

Ultimately, only 16 percent of hospitals were able to give a complete approximate cost for a hip replacement.

Often, a caller was bounced around to a few different hospital departments before being given one of several excuses why an estimate couldn't be provided. The most commonly-cited excuses were, the patient must have an appointment with the physician first, the hospital doesn't give estimates over the phone, or the hospital was simply unable to make an accurate cost evaluation.

Even more shocking, the estimates given by these hospitals encompassed an unbelievably large range. Some facilities said a hip replacement would cost about $11,100, while others said it could be as much as $125,000.

The ranking of a particular hospital didn't seem to have a huge impact on the estimated cost of a hip replacement. Top-tier hospitals offered prices as low as $12,500, while non-ranked hospitals said their costs could run as high as $125,798.

"The variation that we found was striking given that we provided each hospital with identical information about our hypothetical patient," study authors noted.

Climbing health care costs are causing many in the industry to call for a system-wide overhaul to include incentives for people to comparison shop for their medical care needs.

It's a good idea in theory. But, given the results of this most recent investigation, it's one that would be hard to implement.

Individuals with health insurance currently have few incentives to shop around for the most economic practitioner, according to study authors. Indeed, the primary concern for most insured individuals is whether or not a particular provider or procedure is covered by their plan.

The uninsured, even though they have a built-in incentive to try and save money, will likely run into the roadblocks uncovered by this study if they attempt to comparison shop. The fact that price information is so challenging to obtain—even for simple procedures—presents a huge obstacle to the average health care consumer.

The health care industry is poised to undergo significant changes over the coming years. In the meantime, caregivers and seniors should do their research and become as informed as they possibly can about the cost and quality of different care options to help save money and avoid medical billing errors.