Sometimes, when children are admitted for hospitalization due to prolonged fever, the medical team is not always certain about the fever measurements that were taken at the child’s home.
When the team suspects there could have been a technical issue with the measurements, or that the measurements taken by the parents are unreliable, they request an “American thermometer” from the nurse. This is the doctor’s way of asking the nurse to take the measurement (using a regular thermometer, of course) herself (and not have the parents do it).
You’d be surprised at the number of times this little trick has saved me from having to proceed with more invasive diagnostic procedures when it turned out that the child wasn’t really suffering from fever.