To err is human... but to make a potentially deadly mistake and consider it just another normal day on the job, you'd have to work in a hospital.

The newest numbers on medical mistakes are in, and they're uglier than ever: The Department of Heath and Human Services says six out of seven errors -- including potentially fatal blunders -- go unreported.

Now, no one likes to admit to their mistakes... and in the past, doctors and nurses were no exception. They'd often fail to report their mistakes simply to cover their own butts.

But DHS investigators say today's doctors, nurses and other hospital staffers are a different breed: They'll admit to those mistakes... if they could only figure out what constitutes a mistake!

Believe or not, many don't realize when a patient has been hurt by botched medical care. And others make or encounter mistakes so often that they don't consider them mistakes anymore.

It's just another day at the office.

But recognizing those mistakes is supposed to be a key part of the Medicare process -- with hospitals that hope to cash Medicare checks required to report all patients who are harmed by their care.

That includes patients hurt or killed by hospital-acquired infections, drug overdoses, wrong medications, bedsores, delirium from too many painkillers and more.

To find out that doctors and nurses can fail to spot that six times out of seven is just astounding -- and that's not even the biggest problem here. The agency's inspectors also found that even when a mistake is recognized, it almost never leads to changes to prevent it from happening again.

In the new study, independent doctors reviewed a small sample of patient records and found 293 who were harmed by their medical care -- with only 40 of those incidents reported to hospital management.

Of those, only 28 -- less than 10 percent of the original total -- were investigated, and just five led to actual changes in either policy or practice.

But that's just scratching the surface. All told, investigators say 130,000 Medicare patients are harmed by their care every single month -- some of them more than once.

One recent study even found that 15,000 Medicare patients are killed by those medical mistakes every month.

The sad reality is that if you're sick or injured, the hospital is turning into the last place you want to be.