As consumers get savvier about shopping for health care, some are finding a curious trend: More hospitals, imaging centers, outpatient surgery centers and pharmacy chains will give them deep discounts if they pay cash instead of using insurance.

When Nancy Surdoval, a retired lawyer, needed a knee X-ray last year, Boulder Community Hospital in Colorado said it would cost her $600, out of pocket, using her high-deductible insurance, or just $70 if she paid cash upfront.

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