Weeks after doctors removed her right ovary, Leann Carrozzo asked what she thought was a simple question: Why did a routine two-hour surgery cost $25,652.14?

Carrozzo, 43, requested an itemized bill from Good Samaritan Hospital in San Jose. That led to more questions: Why did equipment account for more than half of the charges? Couldn't some of the items be sterilized and reused? If so, why were they so pricey? What was that $2,190 "endo-ta staple" anyway?

Two years later, Carrozzo says she still has no answers. The billing department at the hospital and the insurance company told her they were merely punching in codes from billing documents. After negotiating certain discounts with the hospital, the insurance company paid $17,000 of the bill, and the hospital wanted Carrozzo to pony up another $2,148.

"Shame on them," Carrozzo said. "Shame on the insurance company for paying a bill immediately, apparently without understanding what they were paying for. . . . And how can the hospital be charging these insane amounts and giving lame excuses about codes? . . . Just fix it."

Sounds simple enough, but it's not.

Just about everyone agrees that the medical billing process makes little sense from a consumer's perspective. Prices vary wildly on procedures as routine as a root canal, even within the same community. One surgical procedure will generate a bill from the hospital, another bill from the surgeon, and more from the radiologist, the anesthesiologist and maybe a pathologist. Then there are those pesky pricing codes, attached to everything from a latex glove to a cotton swab. One slip of a keystroke by a billing clerk can dramatically alter the tally.

"Then consider that a hospital might be dealing with 40 different insurance companies, and Medicare and Medicaid, each with a different billing system and format for payment," said Uwe Reinhardt, a health care economist at Princeton University. "Chaos reigns when it comes to billing because nothing is standardized -- not just in hospitals, but in doctors' offices and even pharmacies."

Is it any wonder then that mistakes happen, as Carrozzo suspects was the case with her surgery?

No wonder at all, several consumer advocates say. Mistakes have become so prevalent that a niche industry has evolved to help patients decipher their bills. Pat Palmer, founder of Medical Billing Advocates of America, estimates that she finds multiple errors in 8 out of every 10 hospital bills she reviews. Her organization, made up of 30 independent consultants nationwide, works for individuals, large self-insured companies and even state governments. For a fee, set by each consultant, the group roots out errors in medical billing and insurance reimbursements. It also hosts seminars to train consultants. Medical Billing Advocates says it has found as much as $400,000 in errors when it examined the bills submitted to self-insured companies.

It apparently doesn't take a consultant to spot errors, though. Five percent of the 11,000 people recently surveyed by Consumer Reports said they discovered major mistakes after examining their hospital bills. The patients with $2,000 or more in out-of-pocket expenses, meaning those costs not covered by their medical plans, were twice as likely to uncover errors.

The errors exacerbate consumer frustration with an already troubled health care system. Those lucky enough to have insurance find themselves digging deeper into their pockets to pay premiums, deductibles and co-payments. Some dig so deep that they ruin their credit: Medical debt now ranks as the second-leading cause of personal bankruptcy in this country, after credit card debt. And it's not just because 43 million U.S. consumers are uninsured: About 80 percent of families in bankruptcy due in part or in whole to medical bills were insured, a recent New York Law Review study found.

The future looks even more bleak if health care costs keep climbing 10 to 14 percent each year while wages continue to grow by an annual 2 to 3 percent.

"Consumers will feel more squeezed than ever before," said Helen Darling, president of the National Business Group on Health, which represents the views of large employers. "They will need to pay much more attention to the details of cost-sharing because the money is even more precious and because there will be a larger variety of [insurance] plans, which means more confusion and errors."

Even if insurers pick up the tab for those errors, consumers could ultimately pay the price, said Tom Brennan, director of special investigations with Highmark Inc., a Blue Cross Blue Shield plan based in Pittsburgh.

Every mistake eats into the lifetime cap per patient set by many benefits plans, Brennan said. Yet patients often ignore expenses if insurers reimburse doctors, hospitals or labs without a hassle, he said.

"God forbid you get hit by a catastrophic illness or an extended hospital stay and then find out your benefits have been exhausted," Brennan said.

Not to mention your savings.

Consider the Goodale family in Long Beach, Calif. Last year, Darryl Goodale had a sore throat that went from bad to worse. The diagnosis: throat cancer. The treatment: daily radiation, weekly chemotherapy and a host of drugs to deal with the side effects.

His wife, Ann, initially did not fret about medical costs. "My main concern was his welfare," she said.

But the bills trickled in.

From the oncologists: $37,000. So far, the insurance company has picked up $13,000, she said.

For a biopsy: $7,000. The Goodales paid about $4,000 of that out of pocket.

Then came the whopper: $72,000 from Long Beach Memorial Medical Center for five days of intense inpatient radiation sessions. Insurance paid $16,500 and negotiated a $14,000 discount, she said. That left the Goodales with a $41,500 tab.

That's when Ann Goodale turned to Joyce Zilai, owner and operator of Medical Claims Recovery in Portland, Ore. Zilai spotted what she describes as nearly $12,000 in billing errors.

Among them: Darryl Goodale received six heavy-duty radiation treatments at $4,000 a pop, but he was charged for seven, Zilai said. The itemized bill lists two "initial" visits, each more than $100. And certain costs that should have been included in the price of the operating room -- such as the $48 drape that covered his body -- were charged separately as well. "It's called the nickel-and-dime concept," Zilai said.

Many consumer activists argue that hospitals nickel-and-dime to offset the steep discounts they offer to insurance companies.

The system works like this: Hospitals grant volume discounts to private insurers. In return, the insurers place the hospital on a preferred list of providers and steer millions of patients to them. On that, everyone agrees.

But consumer advocates say insurers don't have the time or wherewithal to review bills line by line. Content with the discounts they receive, they say, insurers pay immediately and let the less egregious errors slip through the cracks rather than risk damaging their relationships with the hospitals.

For their part, insurance carriers say it's convenient, but wrong-headed, to blame them for the system's woes. It's not in their interest, they say, to condone errors or fraud, no matter what the dollar amount involved. The companies consider themselves effective intermediaries in negotiating prices in the a la carte world of hospital costs.

"The health plans in general are the consumer advocates," said Mohit Ghose, spokesman for America's Health Insurance Plans in Washington, which represents 1,300 insurance carriers. "We are the ones doing the negotiations so the consumer doesn't have to."

The negotiated discounts are good but they are diminishing as hospitals gain more leverage, said Paul B. Ginsburg, president of the research group Center for Studying Health System Change in Washington.

In the 1990s, consumers chafing under restrictive managed-care plans demanded more choice and got it, Ginsburg said. Suddenly, insurance carriers found themselves scrambling to lure more hospitals, especially prominent ones, into their networks, making it more difficult, he said, for the insurance companies to negotiate effectively.

Adding to the hospital industry's negotiating clout is a spree of hospital consolidations taking place in certain parts of the country, Ginsburg said.

"So the motivation for hospitals to agree to low prices is much less than before," Ginsburg added.

Meanwhile, as private insurers keep bargaining for discounts, hospitals keep raising their list prices. The idea is to make up for shortfalls created by those discounts as well as for delinquent bills and free care administered to the poor, said Nancy M. Kane, a management professor at the Harvard School of Public Health.

The price hikes especially hurt the most vulnerable: the uninsured, who now pay prices "wildly unrelated to cost," Kane said.

Congressional committees are investigating hospital billing practices involving the uninsured, and several federal lawsuits recently filed accuse not-for-profit hospitals of failing to fulfill their charitable obligations.

Hospitals say they're feeling squeezed. While insurance companies reap record profits, one in three hospitals in this country is losing money every day and another third are barely breaking even, said Carmela Coyle, senior vice president for policy at the American Hospital Association in Washington.

"We've got market areas like Philadelphia where there is only one insurer, and that insurer holds all the cards," Coyle said. "For those who suggest hospitals are in the driver's seat, one would think that would mean you would see better financial situations for hospitals."

Coyle also said the hospital industry is working hard to produce more clear, concise and correct bills. Her group is working with the Healthcare Financial Management Association on educating providers and hospitals about generating more patient-friendly bills.

But in the meantime, she encourages consumers with questions to speak to the patient advocates, consumer ombudsmen and billing specialists available in many hospitals.

"We strongly encourage consumers to be engaged," she said.

Darryl Goodale, the throat cancer patient, has been engaging over and over again with his hospital.

Even before the private consultant intervened on behalf of the Goodales to sort through their bills, Long Beach Memorial Medical Center offered to slash their $42,000 bill to $28,000, Ann Goodale said.

The Goodales countered with an $18,000 offer. "They should get the bill right and then give me a 30 percent discount if they want to," she said.

The hospital said in a written statement: "We understand Mr. Goodale's concerns with his insurance company's refusal to pay a significant portion of his hospitalization fees. We have worked with him and his insurance company to minimize the expenses related to his last hospitalization. As for the organization that reviewed Mr. Goodale's bill, we are unfamiliar with their experience in the health care field and their knowledge of medical billing practices." The hospital maintains that its bill is correct.

Citing privacy laws, Good Samaritan Hospital in San Jose declined to comment on Carrozzo, the California woman baffled by the price of her ovarian surgery.

But in a written statement, the hospital said it helps patients "navigate their bill through processes established in the healthcare industry" and that "financial counselors are always willing to discuss patient bills."

Carrozzo resisted paying her bill for as long as she could -- about a year.

But then a collection agency started calling. Eventually, the hospital offered her a deal, she said: Pay $1,300 instead of $2,148.

"They even offered to have me put it on my Visa," she said. "Wasn't that nice of them?"

Carrozzo buckled and paid.

Staff researcher Richard Drezen contributed to this report.