When Heather was 35, she married a man she'd been dating for four years who already had three children. From very early on in their relationship, they had discussed whether they wanted more children, and consistently agreed that the three he already had were enough. Unless Heather accidentally got pregnant, they would not be having any more.

Two years after they married, the results of a routine Pap smear revealed that Heather had abnormal cells in her cervix that could become cancerous.

She met with her ob/gyn to discuss the test results and decide on a course of treatment. She explained at some length her circumstances and her decision not to bear any children. She asked the doctor to advise her based on that decision.

She was quite dismayed, then, when her doctor started her recommendations by saying, "You might change your mind about having children, so . . ."

Heather explained, "I was concerned that she would not go for the best treatment, because she would be trying to preserve my ability to have children." She was put off by the doctor "who thought she knew me better than I know myself."

Even more disturbing to her than the doctor's stance was the idea that she might be developing cancer.

She asked friends about their experiences with their ob/gyns, and made an appointment to see one that came highly recommended, to get a second opinion.

She started to relax when the second ob/gyn started her remarks by saying, "Because you are not planning to have any children..."

Heather noted, "I knew that I could trust that her recommendations were based on the best chance for my future health." She transferred her care to this doctor. Still, Heather asked if the surgery she advised was really necessary or if something less invasive would work as well -- a reasonable question to ask.

The ob/gyn confirmed that Heather needed surgery, and commented, "I am really glad that you are not planning to have children, because if we were trying to preserve your uterus, we really could be putting you at risk."

Heather was even more relieved after she had the surgery than she had been when she decided to have it. While operating, the surgeon had found a large tumor on her intestine. She removed it. Afterward, she explained to Heather that while the tumor was not cancerous, in time it would have ruptured and caused Heather very serious problems.

Heather concluded, "So it turns out that the hysterectomy saved me twofold. I shudder to think where I would be right now if I had stayed with the original doctor."

Of course, neither of the doctors knew about the intestinal tumor ahead of time, so neither of them could have taken it into account when they told Heather what treatment they thought she should have.

What can you glean from Heather's experience? The most critical point is that it's a red flag if doctors base their choice of treatments on assumptions about your priorities that don't make sense to you -- especially after you've taken the time to explain what your priorities really are.

Doctors are experts in the field of medicine. They may know a great deal more about various treatment options than you ever will. If you need surgery, you need a surgeon. It isn't something that you can look up on the Internet and then perform on yourself. Doctors have a lifesaving role to play.

That said, they can get into trouble -- or, more precisely, get you into trouble -- when they assume that because they are experts in the medical field, they are automatically experts about your life.

Have you ever seen a commercial in which a celebrity -- an actor or a football player, for example -- is pitching an investment firm or insurance or a travel service or a particular drug or some other product?

Maybe an actor who plays a lawyer in a TV show is an expert on investing. Maybe a television starship captain is very knowledgeable about travel services. Maybe a TV and movie actor is the perfect person to advise you about auto insurance.

Maybe. But maybe not. It doesn't logically follow that someone we're familiar with and admire in one role is automatically an expert on a completely different topic.

So why would it make sense to think that doctors, brilliant and skilled though they might be, automatically know which of several legitimate courses of treatment is the best choice for each of their thousands of patients -- when they may know very little about each patient's life? They may never have discussed the patient's priorities, preferences and values.

If you're in the market for a computer, it's not enough to be told, "This is the best computer for you," by someone who doesn't know what you care about in a computer. Do you want a laptop that you can take traveling? Do you want a big desktop that your grandchildren can play video games on when they come to visit? Just knowing your age and gender doesn't give a computer salesperson enough information to know what your priorities are.

Similarly, medical care will work better for you if it is based on your life circumstances and your needs and wants -- not on assumptions about you that are unfounded.