Most of us go to the doctor when we’re sick or for a checkup. Sometimes, our doctors give us tests or send us on to specialists or to the hospital for extra ones—most often as a precaution. We receive advice, maybe a prescription, and stay happy and well. Occasionally, we have to schedule a small procedure or a more complex surgery to fix what isn’t right.

However, for as much as a third of the American public, the situation can be quite different. They go, in good faith, to the doctor’s office, and receive unnecessary tests, treatments, procedures, even surgeries—and were basically healthy to begin with.

And the older you are, the more likely it is you’ll be one of them.

In their new book, The Treatment Trap: How the Overuse of Medical Care Is Wrecking Your Health and What You Can Do to Prevent It, Rosemary Gibson and Janardan Prasad Singh document how billions of dollars are wasted in the United States each year. They explore the reasons why many physicians are overly cautious, incompetent, or under great pressure to produce revenues in a health care system that seems to encourage these practices. Doctors and hospitals are reimbursed by insurance companies and Medicare on a fee-for-service basis—"an open-ended invitation for overuse," says Gibson, a health care expert from the Robert Wood Johnson Foundation.

In addition to bloating the medical economy, unnecessary medical treatment can cause a wide variety of problems for the patient: anxiety, pain, longer recovery times, the need for more treatment, incapacitation, even death. In case after real-life case, The Treatment Trap reveals in frightening detail how this can happen to unsuspecting patients—and how you can protect yourself.

Rosemary Gibson spoke with the AARP Bulletin about medical abuse and overuse.

Q. Billions of dollars are wasted each year in unnecessary medications, tests, procedures?

A. One-third of the money our country spends on health care is overuse and waste. It doesn’t make people better off. That translates to about $700 billion dollars a year. That’s real money that could be used for medical care that people really need.

Q. What is the Green Monster that you mention in the book?

A. The Green Monster is the personification of money in medicine. We’ve built a system with a national credit card that every hospital, doctor, nursing home, home care agency, device manufacturer, pharmaceutical company, and insured patient can use and say: “Charge it!”

The bill goes to Medicare, and the federal government borrows money from China and other countries to pay it. Part of the federal income tax that we will pay on April 15 will go to China for interest on the money the federal government borrows. A substantial portion of this debt is for overuse of medical care.

Q. What about the cost to private insurers?

A. Overuse raises the cost of health care overall to the point that it is becoming unaffordable for everyone, whether they are insured by private plans or Medicare.

Q. Other than the economic cost, explain how overuse can directly affect patients.

A. Take the story of Tom Vallier from Oregon. His doctor diagnosed bladder cancer based on a shadow on a monitor during a cystoscopy, but never did a biopsy to confirm the diagnosis. The doctor told Vallier while viewing the monitor, “Look at that, it’s cancer. We need to get that out right away.” Vallier went ahead and had outpatient surgery because he and his wife believed that when a doctor says you have cancer, it’s true.

After the operation, he learned that he never had cancer. The shadow turned out to be scar tissue. If he had stayed overnight for the procedure in the hospital, the insurance company would have required a biopsy and lab report to confirm the diagnosis before authorizing the surgery. “My husband and I felt so violated,” Mrs. Vallier told me. The lesson here is: Always get a biopsy.