[xxSparkleSxx]

If a doctor misdiangosis someone based on an outside errant lab test, what happens?

I think the situations would be viewed identically. I don't know the exact processes, but lots of documentation would go into it and if the lab that gave the errant lab test has a history of poor results, they may get investigated and closed down.

If this was a one-off error, that will get chalked up to a one-off error. Even if the patient dies.