Often times in health care, particularly insurance, reference is made to "how many belly buttons", which handles pregnancies and the like (no belly button until birth).
I for one find the nomenclature a bit unprofessional.
Why? One of the definitions of "souls" is "a human being; person".
You find it unprofessional because it's also used in a religious way?
Signalling SOB* instead of SOS might be risky.
* Save Our Bodies
I'd always hear it was derived from Save Our Ship, but in reality, it's a backronym, and was chosen simply because it was easy and clear to transmit in Morse Code.