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Proving a Negative

Skull Medical book [morguefile.com]A young lady comes to the emergency department and wants to be evaluated for a … somewhat nonurgent … problem.

Chief complaint: “I’ve lost 50 lbs in the past month.” She felt a little weak as well, but she had just lost too much weight. No other symptoms.

The patient weighed 132 pounds. Her skin wasn’t sagging. Her jeans didn’t appear to be new and they seemed to fit pretty well. Nothing about her seemed abnormal on exam. But she insisted that she weighed 180 pounds just a month earlier.
No old records in the computer.
I asked her if she could show me a recent picture of herself on her iPhone. She briefly stopped texting to check, but she couldn’t find any.
I asked her to show me her drivers license. Nope. Didn’t have that, either.
I was quickly developing an opinion that this was a snipe hunt.

Snipe hunts like this are an example of another conundrum that many physicians face.

We are often expected to prove a negative.

Clinically, I can say that the patient did not appear to have lost 50 lbs in the past month. I can even say that it is unlikely [although not impossible – don’t comment with all your weight loss feats] that any patient could lose 50 pounds in a month.

But what if …?

What if the patient had cancer that caused some type of weight loss and I didn’t evaluate her for it? What if the patient had a bad outcome from a metabolic problem that I didn’t screen for?
What if, as a result of weight loss, the patient had developed an severe electrolyte abnormality or other blood abnormalities?

Retrospectively, if the patient suffered a bad outcome, it would be easy to allege that weight loss is an obvious symptom of [insert bad outcome here] and that Dr. WhiteCoat was careless because he didn’t evaluate the patient for this problem.

I suppose that the same issue holds true for a febrile child. If a three year old with a runny nose had a fever of 102 at home, but looks fine and is afebrile in the emergency department, he’ll probably get a pass on the workup. But if an afebrile 27 day old infant reportedly had a fever of 102 at home, get the lumbar puncture tray ready.

A physician must have a certain degree of risk tolerance in choosing whether or not to do testing to evaluate an odd complaint, but where should we draw the line between “necessary” and “unnecessary” workups?

And in case you were wondering, yes, I did labs and a chest x-ray on the incredible shrinking woman. She was anemic. Her hemoglobin was 10.5. Not enough to hospitalize her, but enough to recommend that she follow up with the on-call physician for a more thorough weight loss/anemia evaluation.

I’m going to be eating my words if she comes back next month weighing 80 pounds.

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