A Long Beach hospital charged Jo Ann Snyder $6,707 for a CT scan of her abdomen and pelvis after colon surgery. But because she had health insurance with Blue Shield of California, her share was much less: $2,336.

Then Snyder tripped across one of the little-known secrets of healthcare: If she hadn’t used her insurance, her bill would have been even lower, just $1,054.

“I couldn’t believe it,” said Snyder, a 57-year-old hair salon manager. “I was really upset that I got charged so much and Blue Shield allowed that. You expect them to work harder for you and negotiate a better deal.”

Unknown to most consumers, many hospitals and physicians offer steep discounts for cash-paying patients regardless of income. But there’s a catch: Typically you can get the lowest price only if you don’t use your health insurance.

That disparity in pricing is coming under fire from people like Snyder, who say it’s unfair for patients who pay hefty insurance premiums and deductibles to be penalized with higher rates for treatment.

The difference in price can be stunning. Los Alamitos Medical Center, for instance, lists a CT scan of the abdomen on a state website for $4,423. Blue Shield says its negotiated rate at the hospital is about $2,400.

When The Times called for a cash price, the hospital said it was $250.