Re: S/O: Well baby checks.. girls different than boys?
While the pediatrician certainly wants to make sure that there is not major rash, a transient rash is really not the purpose of a well baby check. Your pediatrician is going to check femoral pulses which are hard to get through a diaper. They are also confirming anatomical development and looking for other abnormalities. They are checking for inguinal hernias, anatomonical anomolies, other lumps, tenderness, etc.
It is certainly normal for the pediatrician to remove the diaper to check for these things. Failing to do so means missing an entire portion of baby's anatomy. Well baby checks can be pretty quick with a very experienced pediatrician, but they are looking for all sorts of things in those few short minutes and honestly, a rash (unless it is a really terrible rash) is low on their radar.