So you take your grandmother to the hospital. She fell and has severe back pain. After a long, exhausting ER visit, it turns out she doesn’t have any broken bones. Nevertheless, she just can’t seem to stand up without terrible discomfort. It’s probably muscular, but walking is very difficult for her. She lives alone, so you ask, “Can’t she just be admitted for a day or two?”

If I’m her ER doctor, I call the admitting doctor. It probably won’t be her family physician, but will be a “hospitalist.” Not to be confused with “hospice,” the hospitalist is a person who is generally a family medicine or internal medicine practitioner. His or her job is to admit patients to the hospital, care for them during their admission and then discharge them when the time comes.

The hospitalist says, “I’ll come and see her, but I can tell you that she won’t meet the criteria. Can you just treat her pain and try to get her some outpatient therapy?” Nobody likes this answer. But if she is admitted, a person who does what’s called “utilization review” will look at the chart in the morning. The doctor who admitted her will get a phone call and a nasty note, and her Medicare or other insurance will likely say that it wasn’t something they want to pay for, as it could have been treated at home (even though she really can’t move without help).

I then suggest that she could be admitted to what we call “observation” for 23 hours, but she would pay for that out of pocket. That isn’t much fun either. Ultimately, everyone recognizes that it isn’t going to work, and I give her pain medicine and she goes home. She may do well, she may be back. But the powers on high have spoken.

These days, the rules on admissions are getting tougher and tougher. Admission to the hospital is expensive. Insurers, private or state, don’t want to (or simply can’t) spend that money. The specific criteria concerning what can and cannot be admitted seem to change all the time — sometimes because research shows that home is as good as the hospital, and sometimes, alas, for reasons almost purely financial.

I’m just writing this to prepare you for what may happen when you darken the door of your local ER with a loved one. Admission is not a forgone conclusion just because you may think it is. And bringing your suitcase doesn’t make it any more certain.

I wish things were simpler. But as the population ages, as we live longer and have better therapies for dangerous diseases, as we try to do more with less, there just isn’t enough money to do the things we want.

So if you face this conundrum, try not to get mad at anyone. The doctors would probably prefer to admit you if they could. But in an age driven by rules, government and corporate interests, what we want and what we get aren’t often the same things.

But if you do want to act, let me suggest you write to your representative and insurance company. Because what the doctor does in person is increasingly a reflection of what is said in the boardrooms of business and the hallowed halls of Congress.